Mocappys

Motion Capture Made Easy

Planning a Motion Capture Shoot – Action Requirements

November 8, 2011 2 comments

Once you have written the first draft of your list there are a number of technical and artistic requirements you need to consider about each action before you capture any motion. Review each action and add as much detail as possible to it. Ask yourself ‘if I had to explain to someone how to perform this action, what would I need to tell them?’ You may find this requires extra information from other departments who want the action to conform to specific criteria. Adding the extra detail and involving other departments at this stage will help identify any issues before you commit to motion capture.

The better you understand each action the more information you can provide a motion capture company, the easier it will be to direct performers, the more accurately you can capture your data, the less editing the data is likely to require, the less problems you are likely to encounter and ultimately the easier your project will be and the better your final data will look.

Arriving on the day of your motion capture shoot with a couple of mates and inventing actions as you go along is potentially a very bad and expensive way to go about motion capture.

I have tried to make the following list of consideration as exhaustive as possible so you may find that some points aren’t relevant to your particular project

Start & End Pose – What position does the character need to start and end in? Start and end poses are defined by the preceding and following scenes or actions. It is vital you know what position or pose you character needs to start and end the action in as this can be essential for continuity or if the actions needs to blend continuously with another action.

Distance – How far does the action need to travel? The distance an action needs to travel can be determined by the environment the final action will be used in or by the technical requirements of a game mechanic or crowd engine. Make sure you understand exactly what these requirements are as they will affect the way the action is performed and how it finally appears on screen.

Speed – How fast does the action need to happen? As with distance, speed is usually determined by the same factors. The speed of an action can change the way it is perceived and whether it will work in the context of a shot or a game mechanic. The speed can be recorded as a frame length or second count or as a specific description of the nature of the action.

Motivation – What is the motivation for the action? Understanding why the character is doing the action is one of the most important things to consider. For computer games, where the player is providing the motivation try to consider the context the action is likely to take place in. While ‘finding ones motivation’ can sound quite arty, getting it right can massively improve the realism of the action.

Intensity – What is the intensity level of the action? The same type of action may require different levels of intensity at different times during a sequence of shots or for different levels of a video game. Establish a distinction between what the different levels of intensity involve. Make a note of the intensity level for the action and a brief description of what that level of intensity involves.

Variation – How do similar types of actions vary? If you are planning to capture variations of a particular type of action make sure you know what each variation will look like. Don’t be tempted to write Action_01, Action_02 etc. and hope to invent the variations on the day. It can be difficult to come up with a number of different variations at the best of times without the added pressure of being on a shoot.

Environment – How does the environment affect the action? To ensure the final action integrates with the environment properly it is important to consider everything that will impact on how the action needs to be performed. Make sure you know the dimension of every prop, scenery location and scenery object the performer needs to interact with and any marks they needs hit.

Audio – Does the action require audio cues? Sometime an action may require an audio track to take a cue from. This could be in the form of a foley or dialogue track the action needs to synchronise with. Make a note of any audio you require for the shoot so you can request it from the relevant department ready to take on the shoot.

Duration – How long does the action need to last? There are a number of factors that can determine the length of an action like hardware limitations or technical restrictions. Use a stopwatch to time the duration of the shot or yourself performing the action to make sure it doesn’t exceed any of these restrictions. Knowing the approximate duration of each action will also help when estimating the cost of your mocap data.

Response – How quickly does the action need to happen? Response times are usually determined by how the action will be triggered. Some actions may need to begin instantly while others may need to occur at a specific time so they can be synchronised with a particular event. Understanding this can minimise the need to alter the speed or duration of the action during post work.

Context – How does what’s just happened and what’s going to happen affect the current action? It is important to understand how the preceding and following events affect the current action. The action may need to continue or begin in a particular emotional or physical state to maintain continuity. If the actions creates the impression the character is reacting consistently to what is happening around them it will make the character appear much more believable.

Association – What shot or level does the action belong to? This association can be used to identify how often an action is used and if it is necessary. Understanding where the action is going to be used can help assess if a single action can be used for multiple scenarios. It can also help assess if the amount of work required to implement an action is necessary for the amount of times it will be used.

Props – What props are required to perform the action? Include everything the performer needs to use or interact with when performing the action. It is essential to get the measurements and compare the scale of the prop objects against your performer. Also consider the approximate weight of the prop as this has will have an enormous effect on the way the action is performed.

Scenery – What scenery objects will the performer interact with? If the performer has to interact with the scenery or environment in any way, it is essential to get the measurements and compare them with your performer. The mocap space is essentially an empty box, if the action requires anything other than a flat floor to stand on you will need to include it on the list. Don’t forget to include any safety equipment like mats or harnesses that may also be required.

Performers – How many performers are required for the action? Some actions may need 2 or more performers to interact with each other. Write down the number of performers you think will be needed to perform each action. These numbers can then be used to determine how many performers you will require on your mocap shoot and how much it is likely to add to your budget.

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Creating a Motion Capture Move List

October 23, 2011 2 comments

As I stated in one of my earlier post, planning is the key to avoiding pain, misery and expensive mistakes when beginning any motion capture project. I thought now might be a good time to write a few posts to try and explain the types of things you should be thinking about at the start of your project before you even begin capturing any data.

A move list is exactly what it sounds like, a list of moves you plan to capture for your project. It can begin as a simple text list and develop in to a complex spreadsheet containing detailed information about every aspect of an action.

It is worth investing as much time as possible at the beginning of a project to ensure the move list is as comprehensive as possible. Understanding exactly what you are going to capture will provide you with an idea of the scale of the project and what resources it will require, improve the quality of the captured data and reduce the time taken to edit it, avoid potential problems and costly mistakes and ultimately decide if motion capture is right for your project.

So where to begin…..

First Draft

One of the best way to begin creating your move list is with a draft version. Use this as a brainstorming session where everything you think of as you review your reference material gets added to your list. Don’t spend time editing or looking back over what you write, simply write it down

At this stage don’t worry about specific details, instead write a short descriptive title for each action, which character will be performing it and which scene, sequence or level it relates to. It is also worth noting any questions you have about the action so they can be addressed later. Keeping track of this information will help remind you how and where you intended to use the action, what details you still need to think about and identify actions that can be removed because the section they belong to is no longer required or has been changed.

Unless you know exactly what actions you require when you begin writing the draft list, it is a good idea to over estimate the actions you will require. Plan to use the largest number of characters performing the most complicated and varied actions possible. The more scary comprehensive you make the list now, the less chance you will have of underestimating the amount of actions, work and ultimately money the project will require.

Reference Material

To begin your list you are going to need to gather as much relevant reference material as you can from as many different sources as possible. Some of this may be provided as part of the brief and some you will need to gather yourself. When gathering your own reference, don’t limit yourself to just your imagination. Try to find as much reference of the same types of actions in similar situations as you can. The more research material you can find, the easier it will be to create a large variety of appropriate actions and still have alternatives in case your initial ideas aren’t approved.

Below I have listed some of the main types of reference you are likely to come across and how you can use them.

  • Script/Design Document – These type of documents provide you with the movement, actions, expression, and dialogues of the characters for your project in a written format. Read through them and try to visualise how you think the scene will look, how many characters you think will be in the scene and what action they will need to perform.
  • Storyboards – Storyboards provide a graphical representation of the script, usually with an indication of camera direction and dialogue. These will help give an idea of the number of characters in the shot but as these are only still images you will still need to need to try to visualise what each character will be doing.
  • Animatics – At its simplest, an animatic is a series of still images edited together and displayed in sequence with a rough sound track and timing. These can contain approximations of the final camera moves, framing and shot duration, but like the storyboards you will still need to try and visualise what the characters will be doing in the shot.
  • Previsualization – Theses are usually computer generated sequences used to visualise complex scenes in a movie before filming commences. They can provide some of the best reference as they should give a clear idea how the final shot will look, it’s duration, the number of characters required and possibly some approximation of the type of actions the will be required.
  • Live action reference – This can include actual live action plates from the production you are working on or illustrative clips from the internet, movies or videos of rehearsal sessions. This reference is often the most representative of the final actions that will be required as it usually demonstrates the duration, framing and type of action as well as the number of characters that are going to be required.
With your completed first draft you should have a good idea about the size of your project and how much work you’re going to have to do. In the next post I’ll cover some of the details you’ll need to consider for each move, making the move list seem even more daunting!
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Realigning animation in MotionBuilder

April 16, 2011 No comments

Files may require repositioning from their original capture position for a number of reasons. Sometimes the animation may require positioning a certain way to work in a game engine or crowd simulator or takes may require aligning to to match geometry in an environment.There are a couple of different ways to realign a character in MotionBuilder. One uses the often over looked “Move Keys” and the other uses the Story tool. Using the Move Keys can be a quick and simple way to reposition a character in a scene while the Story Tool can give much more accurate results, especially when aligning a characters down a specific axis.

Using Move Keys

  • Open the file to be re-aligned. This file can contain single or multiple characters which require realigning.
  • Select the root of the character. This is the top node of the skeleton hierarchy, usually the hips. You can check by simply moving the object. If the rest of the skeleton moves with it you have the correct joint.
  • Set the Translation and Rotation to GLOBAL space. This can be set via the Reference Mode menu in the Viewer toolbar on the right of the Viewer window or by pressing (F6).
  • Select the Translation and Rotation Curves. In the FCurves window frame all the keys (press (A) with your pointer over the FCurve window.) Highlight the Translation and Rotation channel filters in the Properties pain on the left side of the FCurves window. Right click in the FCurve window and choose “Select All” from the pop-up menu.
  • Reposition the character. With the root of your character still selected move it to the correct position in the scene or type in zero values for the X,Y,Z Rotations and the X and Z Translations. (DO NOT change the Y value or your character will drop below the ground)
  • Click Move Keys. In the Key Controls window click Move Keys. MotionBuilder will alter the value of the Translation and Rotation curves so your character will be repositioned to the new location in the scene.

Using Story Add character to story.

  • Create a Character Animation Track.With Story turned on right click in the Story tool and select Insert Character Animation track or select the entire skeleton (Space-Bar RMB the top of the skeleton hierarchy) and Alt+LMB drag it in to the Story window.

  • Insert Take. If you have the take that requires realigning loaded you can Right-Click in the Story clips window and Insert Current Take from the popup menu. Alternatively you can drag a file from a Favorite Path in the Asset Browser window directly in to the Story Tool.
  • Turn on Ghosts. In Story window select the clip you have just inserted and turn on Show/Hide Ghosts (use X-Ray mode if you can’t see the clip trajectory). This will allow you to manipulate the position of the clip and see the gross motion of your character during the clip. The gross motion is displayed as a line under your character which represents the start and end position of your character in the clip.

  • Reposition character. To centre your character in the scene, switch to Global Reference mode (F6) and type in zero values for the Translation and Rotation of the clip or use the manipulators to reposition the clip to desired location. You can reposition the entire clip this way or use the razor tool to cut the clip and reposition individual sections.
  • Plot animation. I usually avoid using the plot in the Story tool as this will add a keyframe to everything in the scene. Select the objects you want to plot animation on to and in the Key Controls window set the Keying Mode to TR and then use Animation>Plot Selected (Selected Properties). This allows you specify what channels on the selected objects are plotted.

  • Set Plot Options and plot. Set the options you require for your particular project in the Plot Options dialogue box and press Plot. Turn off Story. Once you have plotted all the joints and characters in to their new positions turn off Story. If you have been successful the character will remain in it’s new position.
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Merging Characters in MotionBuilder

February 26, 2011 No comments

In this post I will explain how to merge two animated characters in to one MotionBuilder take. The issue people often seem to have is once they merge the new character in to the scene the old character stops moving. The following steps and the settings I suggest for the “Merge Options” window will hopefully prevent this from happening and allow you to recombine two or more characters in to one MotionBuilder take.

Open the first file

  • Open the first character file. File>>Open the first MotionBuilder file containing one of the character you want to merge together.
  • Copy the current take name. Copy the name of the current take from the Navigator>>Takes window. The take name of the file you are going to merge in needs to have the same name as the take you are merging it in to.

Merge the file.

  • Merge the second character. Click File>>Merge and navigate to the MotionBuilder file containing the second character to be merged in to the scene.
  • Set the Merge Options. It is possible to Append, Merge or Discard any elements from the file you are Merging using the Merge Options window. Append will add objects, Merge will update any elements in the scene with same name and Discard will not merge the element.
  • Append All Elements. It is possible to quickly change every element in a column by Right Clicking in the appropriate column and choosing Merge, Append or Discard All Elements. To change individual elements simple click in the box beside the element to display the appropriate icon.
  • Load Animation. If you are merging an animated character, make sure you turn on the Animation.
  • Import Take. Check the tick box next to the take you want to import.
  • Rename the Take. In the “As Take…” column double click and paste the take name copied in the previous step. This ensures the name of the take you are merging matches the name of the take you are merging it in to..
  • Add Namespace. You may need to “Apply Namespace” to the objects and character you are merging to avoid naming conflicts. Tick the “Apply Namespace” box and change to either “Use File Name” or ‘Use New Namespace” to add your own.
  • Discard Settings. I usually discard the “Settings” (Base Cameras,Camera Switcher, Current Camera, Global Lighting, Transport) objects and stick with the current ones I have in the scene. You can Right click and Merge all Settings to update these objects if you need to.
  • Merge. When all the settings are correct click Merge.

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Creating a Live Character Shadow in MotionBuilder

November 7, 2010 1 comment

Adding a Live Shadow to a scene is a simple process which can help ground a character without the need for an environment. The live shadow can be added to an existing scene to make renders a little more interesting or to a scene ready for editing or using during a live motion capture session to help ground the character.

The main steps to creating the show are

Create an Infinite Light

  • Add a light in to the scene. In the Asset Browser>>Elements folder drag a “Light” object in to the Viewer window.
  • Position the Light. Set the position of the light by moving it above your character or typing values in to the viewer window. Something like 0,1000,0 can be used for the Y translation as long as it is higher than your character.
  • Change to Infinite Light. In the Navigator window go to the Navigator tab and expand Lights. Double click the light you’ve just created and change it’s Type to Infinite Light from the drop down menu.
  • Turn off Cast Light On Object. In the same window un-tick the Cast Light On Object tick box.

  • Rename to “ShadowLight”. Right click the object in the viewer or in the Navigator and Rename the light to “ShadowLight”

Create a Floor Plane

  • Add a Plane in to the scene. In the Asset Browser/Elements folder drag a “Plane” object in to the Viewer window. This will act as the floor for the scene
  • Position the Floor Plane. Position the plane at the required floor level under your character.
  • Scale the Plane. Scale the floor plane so the character remains over it during the animation. If you don’t know where the character is going to be in the scene, try a large number for the scale value.

  • Disable Transformation and Selection. Under Asset Browser>>Properties>>Viewer Options turn off Enable Transformation and Enable Selection to prevent accidentally selecting or moving the Plan when working with the scene. The Shadow Plane can still be selected in the Schematic View or Navigator under Scene objects.

Create a Live Shadow Shader

  • Add a Live Shadow Shader to the Floor Plane. In the Asset Browser>>Shaders folder drag a “Live Shadow” shader on to the plane.

  • Replace All. From the pop-up menu choose Replace All to replace any shaders already assigned to the plane. You should see the floor plane disappear and a shadow appear under your character.
  • Set Display Mode to Texture and Shaders. If you can still see the floor plane make sure the Viewer>>Display>>Model Display is set to Textures + Shaders.

  • Rename Shader to “LiveShadow”. Right click the object in the viewer or in the Navigator and Rename the light to “Live Shadow”


Create a Shadow Group

  • Add objects to a group. Select the Floor Plane, Shadow Light and Shadow Shader and  click Create in the Group window.
  • Rename Group. Double click the name of the group and change the name to something more recognisable like “Shadow”.
  • Prevent selection. In the Group window un-tick the Pick column to stop accidental selection of the objects in the Viewer.

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Creating an In-Place Looping Animation in MotionBuilder

October 17, 2010 No comments
This tutorial is a follow on from Creating a Looping Animation in MotionBuilder, showing you how to edit a traversing animation like a walk or run so that it loops on the spot
There are two ways to do this in MotionBuilder:

  • Using In Place Mode on the Control Rig

  • Deleting Key Frames in the FCurve window

    • Using In Place Mode

    • Plot the take to a Control Rig. If the animation isn’t already on a Control Rig, in the “Character Controls” panel select Edit>Plot Character…>Control Rig and if prompted create an FK/IK rig. Set the options in the Character Pop up window to your specific scene requirements and click Plot.

    • Lock the translation of the character. In the Character Settings tab under Character >> Modifiers >> In Place there is the option to Lock the X, Y and Z translations of the control rig.Tick the box that corresponds to the axis or axes your character is traversing along to lock the character in place.
      • One problem you may find when using In Place mode is it can be very difficult to edit the animation while the Control Rig is locked in place. The Control Rig will continue to move as it did in the original animation while the character remains locked in place. This breaks the feeling of editing on the character, especially if you are in “Model Only” view. I would recommend completing all your editing before locking your character in place or temporarily activating it to test Base Poses and edits are working correctly.
    • Re-Crentre the character. If the character moves from the centre of the scene when you activate In Place mode it is possible to re-center it.
      • Copy the Global position (F6) of the top node of your character’s skeleton, this is usually the hips.
      • Select the Character Control Root and paste the inverse value of the hip position on to it. (i.e. Hip Z Translation = 70 CharacterCrtl Z Translation = -70 )

    Character Control Root

    • Plot the take to the Skeleton. When you are happy everything is working correctly and all the editing is complete, plot the animation to your skeleton. In the Character Controls select Edit>Plot Character….>Skeleton.

    Deleting Key Frames in the FCurve window

    • Select the character’s hips. Select the character’s hips in either X-ray mode in a camera view (Ctrl+a) or switch to Schematic View (Ctrl+w) and select the node there.
    • Select the channel to delete. First identify which axis the character is traversing along.Then in the Navigator >> FCurves tab select the Translation channel the character is traveling down from the Properties Pane on the left side of the FCurves tab. As a rough guide if you have the correct channel the keys should appear to form a diagonal line across the FCurve pane.

    • Drag Select all the keys except the first one in the FCurve pane. Still in the FCurve pane right click and select Delete from the pop up menu.This should remove the translation from the animation and the character should be animating on the spot.
    • Re-Centre the character. If you need to re-centre the character you can select the remaining translation key and change it’s value to zero. This will reposition the character to the centre of the scene.
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    MotionBuilder Pipeline

    August 12, 2010 No comments

    In this motionbuilder tutorial I will take you through the processes involved in preparing and exporting your character into motionbuilder and then importing your lovingly crafted animation back on to your character. Because of the many different possible combination of plug-ins and software versions I will try to make this tutorial as generic as I can while still covering all the essentials. The only downside to this may mean you have to search online or test different plug-in settings to get the desired results with your particular combination of software and plug-in.

    So excuses and apologies out of the way, let us begin

    The main topics covered in this tutorial are:

    Building a Skeleton for MotionBuilder

    • Create a skeleton. The first thing you will need to do is create a continuous FK skeleton hierarchy for you character if you haven’t already done so. It is possible to have a complex skeleton with auxiliary joints to help with skinning and deformations, but the main joints of your character will need to be in a continuous parent child hierarchy.
    • Align rotational axis. I’m not going to go over the principals of building a skeleton for your character, there are lots of good tutorials online about how to do this. The one thing I would recommend is that you have one of the joints rotational axis aligned down the joint. This will make your animation curves much easier to read and edit in an fcurve editor as you won’t be dealing with compound rotations. It will also create smaller files when exporting to a game engine for instance, as you won’t have unnecessary data on joints like the knees and elbows that only rotate in one axis. The cleaner you build your skeleton the easier it will be to work with and fault find should you run in to problems.
    • Joint Naming. MotionBuilder does require a specific naming convention if you want to use the “drag and drop” Characterization on your character. However, it is possible to use your own naming convention for joints if you want or need to, it will just require a little more work to Characterize your character once you have it in MotionBuilder. Also once you have characterized one character with your own unique naming convention it is possible to extract that naming template and use the Character it creates to drag and drop on to any other character with the same joint names.
    • Required Joints. For the Characterization process to work inside MotionBuilder your skeleton must contain at least the “Base” set of joints listed below.
      • Hips
      • LeftUpLeg
      • LeftLeg
      • LeftFoot
      • RightUpLeg
      • RightLeg
      • RightFoot
      • Spine
      • LeftArm
      • LeftForeArm
      • LeftHand
      • RightArm
      • RightForeArm
      • RightHand
      • Head
    • Remaining Joints. Beside the required “Base” joints listed above the Character Rig also supports:
      • Auxiliary Joints – For single toes, shoulders, neck and single fingers
      • Spine Joints – Up to 9 spine joints are supported
      • Roll Bones – Currently only one roll bone per limb is supported.
      • Left and Right Hands – For Fingers
      • Left and Right Foot – For toes
      • Left and Right In-Hand – For the joints in the hands
      • Left and Right In-Foot – For the joints in the feet
      • Neck - Currently supports up to 9 neck joints

    • Skin the character. Before you skin your character delete the history from the mesh or collapse the stack as this information will not be exported to MotionBuilder. You can skin your character using rigid or smooth skinning as both are supported by the exporter. If you have any extra rigid geometry for things like eyes, teeth or finger nails these can simply be parented the appropriate joints for export.
    • Align the Character. For the characterization process to be successful in MotionBuilder your character must be aligned in a T-Pose facing down positive Z. MotionBuilder relies on the character begin positioned in this way to set-up things like the full body IK and the offsets when mapping animation between different characters.The character’s arms, legs, fingers and toes should be positioned so the mesh, not necessarily the bones, appears perfectly straight. (Sometime straightening the bones can cause the characters limbs to appear bent in an unnatural manner). Once the character is in the T-Pose you can rotate it to face down positive Z.
    • Group character elements under a single node. It can be useful to group all the separate elements of your character under one node. I group any separate mesh elements under one node and all the skeleton nodes under another. The skeleton group node can then be used as the “Reference” in the Character Definitions Tab when characterizing your character. I also group the skeleton group under a “Scale” node so I can easily change the scale of the character in MotionBuilder if necessary. I then group the “Scale” node and mesh nodes under one last group so all the elements of the character sit neatly under one group. This makes it much easier to identify and select everything that belongs to the character in a scene.

    • Save a clean file. Once I have finished the character set-up I save a “clean” version of the file to use for importing animation back from MotionBuilder. This means anything that cannot be exported to MotionBuilder is preserved in the scene and I only have to import animation on to the character which is much faster than importing an entire scene.
    • Export as fbx. Because the plug-ins vary quite a bit between the different version of MotionBuilder and Maya/Max it is worth going on line and finding out exactly what objects the version of the exporter you are using supports. You should also find an explanation about what each of the different options in the exporter actually does. The early ones were pretty simple and only asked if you wanted to export animation and geometry. The more recent plug-ins now support more items and will require a little more investigation. As a basic guide the more recent plug-ins should support:
      • Smooth and Rigid skinning
      • Polygons and Nurbs surfaces without history
      • Any UV sets and Multiple Shaders on geometry
      • Simple shaders.
      • Basic constraints
      • Blend shapes ( Include the target shapes when exporting and only have one shape per channel).

      For the 2011 plug-in try here
      For the 2010 plug-in try here

    • Test the Pipeline. Once you have your character in MotionBuilder create some key frames on it and import the resulting file back on to your character to make sure everything is working as expected. It’s better to find any problems at this stage before you start creating lots of animation and then find you have to start changing the rig and remapping animations.
    • Blend Shapes. If you are exporting Blend shapes to MotionBuilder for facial animation the target shapes must be in scene when exporting. These will not be visible when you open your scene in MotionBuilder, but they are required for the export process. Also the blend shapes can only contain one target per channel. In-line or progressive are not supported.
    • Constraints. The more recent versions of the fbx exporter does support basic constraints. IK, Point, Rotation and Parent constraints can all be exported in to MotionBuilder. More complex constraints like Expression are not supported by the exporter, but they will still work if you only import the animation from a completed MotionBuilder file on to your character. Importing the animation on to your character apply the animation to the main joints while maintaining any expression constraints in your scene.

        • Importing a character into MotionBuilder

        • File>Import your character in to MotionBuilder. If you are using MotionBuilder 2009 or above you will need to use File>FBX Plug-in Import… or File>FBX Plug-in Merge… to import your character. Pre MotionBuilder 2009 use the File>Import or File>Merge options. File>Import only allows you to specify which animations are imported, while File>Merge allows much more control over exactly what is merged in to the scene.
        • Re-size joint display size. The display size of the joints may require adjusting once you have imported your character in to MotionBuilder. In the Asset Browser>>Properties>>Skeleton Node Settings>>Size change the value until the bones appear the right size. This only affects the display size of the joints and will not affect the actual joint size or scale.

        • Scale the character. It may be necessary to re-scale your character due to different unit scales or to match the size of a performer when re-targeting data. If you created the “Scale” node before exporting your character you can use this or you can create a null, parent the skeleton to it and apply a scale to the null object.
        • Align the character. If you haven’t already aligned your character as described above, do so now.
        • Characterize the character. Now you have your character in MotionBuilder it can be characterized using this handy tutorial.

            • Exporting animation from MotionBuilder

            • Plot the animation to the Skeleton. In the Character Controls window click Edit>Plot Character… and click Skeleton from the pop-up window.

            • Plot any animated or constrained objects. Select all the objects you have animated or that have constraints attached to them and plot the animation to them. In the Key Controls window set the channels you want to plot from the Keying Mode drop down. Click Animation and from the drop down menu select Plot Selected (Selected Proerties)… to plot the animation to the objects you selected on the channels you chose.
            • Re-Scale the character. If you changed the scale of your character after it was imported, you will need to return it back to it’s original size be resetting the value on the Scale node.
            • Save the scene. Using File>>Save As… save the completed scene as a .fbx file ready to be imported on to your character. It can be useful to keep a separate “MoBuImport” folder containing your completed files ready for importing


            Importing an FBX File

            • Import the file. MotionBuilder files can be imported on to your “Clean” character file or in to an empty scene, using the importer to re-create all the objects from the fbx file.
            • Plug-in Settings. Depending on which version of 3D software you are using and which version of the plug-in you have, the import options can vary greatly, so here  a general general guide on what options to use:
              • Turn on Animation – Without this the animation won’t be imported
              • Animation Take: This drop down list will be populated with all the takes saved in the fbx file. Simply select the one you want to import.
              • Fill Timeline – This will set the correct start and end time in your scene for the take you are importing.
              • Set File content: Update scene elements/Exclusive merge will import just the animation from the fbx file on to objects with the same names as those in your current scene. This option can be used to import animation on to your clean character.
              • Set File content: Add to scene will add the entire contents of the fbx file to your current scene including animation geometry and anything else supported by the importer plugin you are using.
              • Protect driven keys. Activating this will prevent the plug-in applying animation to any joints which use set driven keys or expressions

            So there you have it, how to prepare, export and import your character into MotionBuilder. As with any of the tutorials, please add your own comments on different work flows or let me know if any of this isn’t making sense.

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    Creating a Looping Animation In MotionBuilder

    August 1, 2010 2 comments

    In this post I will take you through the processes required to create a walk cycle from motion capture data. I have provided an explanation and possible work flow suggestions at each stage of the process. Hopefully this will enable you to create not only a beautiful walk cycle, but also help you understand some of the principals and practices involved in motion editing.

    The main steps covered in this tutorial are:

    • Importing an animation file on to a skeleton

    • Adding a Character to the Story Tool

    • Creating a Loop in the Story Tool

    • Aligning a take in the scene

    • Plotting a take to a Control Rig

    • Creating a Loop Pose

    • Applying a Pose

    • Correcting footsteps

    • Editing errors in an animation

        • Importing an animation file on to a skeleton

        • Open a MotionBuilder file containing the character you are going to use for editing. I usually save a “clean” file for each character once I’ve characterize it to use for editing or importing in to scenes.
        • Select the characters hips. In the Viewer change to X-Ray view (press Ctrl+a in the Viewer) and LMB select the hips of the skeleton or switch to Schematic View (Ctrl+w) and click the hip node to select it. Selecting the hips allows you to specify which heirarchy you want to import the animation on to.
        • Select the files you want to import. Click File>Import…. to open a pop up window to select the files you want to import for editing. In the Import Options select “Merge: In Selected Hierarchy”, turn off “Ignore Model Types, Create Unmatched Models and Import Scaling and set Take Start/End: to Import From File.
          • If you get a warning pop when you try to import the file, check the number of models MotionBuilder can match is about the same as the number of joints in your skeleton. If it is click continue other wise check the file you are importing contains the right skeleton and has the correct naming convention.

        • Save the file. Once you have imported the animation play it through and check the characters is moving correctly and there are no errors like flipped limbs or popping in the animation. If everything looks good save the file under a new name like **takeName_EDIT** It’s very easy to forget you have imported the animation in to your “clean” character file and save over it or discover Ctrl-a ( X-Ray) and Ctrl-s ( Save ) a little too close sometimes.


        Adding a Character to the Story Tool

        • Insert a Character Animation Track. In the Story Tool activate Story and right-click and Insert > Character Animation Track. Select your character from the …Character drop down menu. Rename the Character Track to the name of the take you are editing. (Right-Click > Rename. )

        • Insert Current Take. Select the Story track you have just created and RMB>Insert Current Take to import the animation from the current take in to the Story tool. Select the clip in the “Story” window and frame it by pressing “a” to frame all or “f” to frame selected.
          • If you haven’t characterized your character it is still possible to use the Story Tool to edit the animation on a skeleton. Select the entire character skeleton by SpaceBar+Right-Clicking the hips of the character. This selection can then be dragged in to the Story Tool using Alt+LMB, which will automatically create an animation track for the selected objects.


        Creating a Loop in the Story Tool

        • Find a section of the take to create the loop from. First you need to find a section of the take where the character is traveling at a constant speed in a straight line. The middle of the take is usually a good place to use as the performer will have settled in to their stride by this point. You can always test how well the section you plan to use will loop by altering the playback range to the required frames and viewing the action in an orthographic window with the character walking towards camera. If the character appears to be looping at this point then you should have very little work to do. If there character is “popping” quite a lot as the take loops or appears to be speeding up or slowing down it is probably worth considering using a different part of the take.
        • Find a start pose. Once you have identified a good section to use for the walk cycle you will need to find a pose that will be easily recognisable again in the take. One foot passing the ankle on the other leg is a good pose to use as it’s half way through the walk and is also an easy pose to identify later in the take. Using an orthographic view find the frame where the foot and ankle are roughly aligned. It is very rare that both limbs will line up exactly so you will need to ensure if one foot is slightly behind the ankle in your start pose you use the frame with the foot slightly behind the ankle for the end pose.

        • Trim the clip. Set Loop/Scale Clips to Loop and turn on Snapping. Trim away the unwanted frames before the start pose by dragging the start of the clip to the correct frame. Be careful not to move the entire clip when doing this. If the cursor is in the correct place over the clip you should see it change to the trim tool and the last frame of the clip shouldn’t change when you change first frame. It is also possible to change the start frame of the clip by double clicking the bottom number at the start of the clip and typing in the frame number of your start pose.

        • Set the end frame. Find a matching end pose by stepping through the animation to a frame where the character is in a pose that resembles the start pose as closely as possible. Repeat the method used to create the start pose, this time trimming away the unwanted frames after the end frame. Drag the end of the clip to the frame containing the end pose, again being careful not the drag the whole clip. Or double click the bottom number and enter the frame number of the end pose.
        • Re-time the clip. Change the clips start time to 1 by Left click dragging the entire clip so it starts at frame 1 or double click the top number at the start of the clip and change it to 1. Then re-set the start and end frame of the Transport Controls by right clicking the track in the Story window and selecting Frame Start/End.


              • Aligning a take in the scene

              • Turn on Ghost Visibility. Select the clip and turn on Show/Hide Ghosts and change the “Viewer” to Normal or X-Ray mode so you can see the trajectory of the clip.
              • Center the take. With the clip selected press “t” and translate the clip globally so it is positioned at center of the scene or type in zero values for it’s x, y and z positions. Repeat the same process with the rotation to align the trajectory of the clip down an axis. For a locomotive action like a walk I usually align the clip to face down positive Z so the character walks towards the front orthographic camera. Aligning the animation this way allows you to watch the playback in an orthographic view and the character will appear to remain on the spot.
              • Check the loop. Change to the appropriate orthographic view so the character is walking directly in to camera. Turn on continuous playback and play through the animation to see how well the animation loops. As the first and last frames will be almost identical there should be very minimal popping as the animation loops. Also check the speed of the action looks consistent and the character doesn’t appear to be speeding up or slowing down. The better the loops looks at this stage the less editing you will have to do later.


              Plotting a take to a Control Rig

              • Plot to the Control Rig. In the “Character Controls” panel select Edit>Plot Character…>Control Rig and if prompted create an FK/IK rig. Set the options in the Character pop up window to your specific scene requirements – I usually use Plot On Frame, set the Plot Rate according to the project I’m working on, turn on Unroll Rotation Filter and turn off Constant Key Reducer.

              • Turn off Story. It’s a good idea to turn off Story at this stage to prevent confusion later. It’s surprising how many times you’ll forget to turn it off and then wonder why the edit you’ve just plotted to the skeleton doesn’t seem to have changed the character animation.


              Creating a Loop Pose

              • Pose the character. Begin by editing the characters pose on the first frame to create an appealing start pose. Align the head so it is looking in the correct direction and turn on Reach R and pin the effector rotation. This allows you to adjust the rest of the characters body without affecting the position of the head. Remove any mesh intersections or other artifacts that may be visible and finally pose the fingers. Always remember to switch between different view-ports to make sure the pose looks good from all angles.

              • Set  Full Body Key. When you are happy with the pose, turn on Fully Body Keying Mode and set a Flat key on layer 1. If you are currently working on the Base Layer then you will get a pop-up recommending you key on Layer 1. Click Go to Layer 1 if you get this pop-up otherwise you will key over the first frame of the original animation.
              • Create a Pose. Add the pose to the pose library by pressing the Create button in the Pose Controls window. When you see the new pose appear in the Poses list, which may require expanding, Right click it and Rename it to something appropriate so it is easily recognisable.


              Applying a Pose

              • Paste the pose. Go to the last frame of your animation and paste a fully body pose of the pose you’ve just created matching the current position of the characters hips in Z and set a flat key.
              • To break that down a little -
                • In the Keying Mode section of the Character Controls window turn on Full Body mode. Using Full Body Keying Mode will apply any pose to the entire body of the character. It is also possible to paste a pose to a Body Part or Selection by selecting the appropriate Keying Mode. This can be used when applying finger poses to an animation.
                • Select the characters Hips in the Character control window. Selecting different limbs tells MotionBuilder to paste the pose relative to that limbs current position. If you are using Body Parts or Selection the pose will only be applied to the selected limbs which can be useful for applying hand poses – but that’s another tutorial.

              • In the Pose Controls window turn off everything except Match Translation Z Component and Respect Gravity. Once you have identified which limb to align the pose with you have the ability to align a pose to that particular limb’s current position. When creating a looping animation like this one you only need to match the pose along the axis the character is traveling, in this case positive Z. The best way to see how the different combination of match options, limb selections and Keying Modes works is to try them out yourself.

              • Paste the Pose. It is possible to paste the pose using the paste button in the Pose Controls window or by double clicking the pose name.
              • Set a flat key.
              • Check the animation. Turn on Continuous play in the transport controls and play the animation back to check it is looping correctly, ignoring the sliding feet for now. You can view the animation in an orthographic view so the character appear to be in walking in place or you can turn on “In place” mode in Character Settings > Modifiers > In Place > Lock Z. Also try flipping between the first and last frame to make sure they are identical.


              Correcting footsteps

              • Key on Body Parts. Turn on “Body Part” in the “Character Controls” panel so any edits or key frames you set will only effect the currently selected limb and not the entire body.
              • Stabilise the planted foot. Go to frame one and select the foot controller for the foot that is currently planted on the floor. Right click on the key frame in the Transport Controls or Select the Translation keys in the FCurves window and right click and “Copy” the key. Scrub through the animation to the frame where the toes of the planted foot are just leaving the floor and paste the key on that frame. With the same foot still selected, Copy the last key of the take. Then scrub back through the animation to the frame where the heal touches the floor for the last time and “Paste” the key over it.
              • Set interpolation to Flat. Select all the keys in the Transport Controls by right clicking on the time line and selecting “Select All” from the pop up menu. Right click again on the time line and choose “Interpolation > Flat” to set all the tangents on the keys to flat. Changing the tangents to flat helps prevent unwanted movement on the feet.
                • The key frames created on Layer 1 are actually offsets from the objects original position. These offset will remain until the limb is moved and another key is set. As an offset has been created at the beginning and end of the take the when we created the poses the foot will interpolate between these two positions over the length of the animation. This can create a noticeable “sliding” effect in the foot especially when the foot should be stationary. By copying and pasting the correct keys we can maintain the offset position of the foot when it should be stationary and force the interpolation to happen while the foot is off the floor. This will look more natural and hopefully “hide” the edit. The same principle can be applied when editing any limb in this type of situation.
              • Stabilise opposite foot. The same basic idea can now be applied to the other foot, except his time the position that needs fixing is in the middle of the animation.Scrub through the take until the opposite foot contacts the floor with the heel. Create a flat key or a zero key on this frame and copy and paste this key frame to the frame where the toes are just leaving the floor.
                • This creates the same type of fixed or constant key we just created so the foot will remain fixed while it is on the ground. It may be necessary to try the foot in a few different positions to find the position that creates the least or no errors. Keep checking the the character still looks to be balanced and there that you haven’t created any popping or hyper-extension in the leg by over stretching the IK. A good way to correct these types of errors is to use the Fcurve editor. By selecting the appropriate channels on both key frames at the same time you can make minor adjustments to their values rather than having the adjust one key frame and then update the other.
              • Check for sliding. Play through the animation and check the feet aren’t sliding or floating when they should be planted. If they are, begin by checking you have all the tangents on layer one set to flat. Then check the errors aren’t on the base layer/original animation.

              Editing errors in an animation

              • Remove artifacts. Look for any other artifacts that may have been created when adding the poses. Where possible work in Body Parts Keying Mode when editing out things like mesh intersections, hyper extension of limbs or “unappealing” poses.
              • Edit one limb at a time. Try to edit all the errors on one body part at a time before moving on to the next, unless the other body part is causing the problem. Sometime the error you can see may be caused by a different body part. For instance lowering the hips might solve any hyper-extension you are seeing in the legs with one key frame rather than editing each leg individually over the length of the animation.
              • Keep all edits on one layer. I would recommend trying to keep all your edits on one layer. It is possible to create lots of different layers to edit your animation on in MotionBuilder, but unless you have a very disciplined way of working I would recommend keeping all your keys on the same level. It’s very easy to plan to edit each limb on a different layer and equally as easy to accidentally edit the wrong limb on the wrong layer and then be unable to find the key that’s causing the problem in your animation. It is also much simpler to adjust all the keys on a character if all the keys are on one layer if. The only time I would add a second layer is if a simple offset could can be applied to the entire animation to fix it or change it. This would create a single offset but preserve any edits I’ve made on the lower layer.
              • Edit on extremes. If there are parts of the animation that require editing, try to do all your editing on the most extreme frames using as few frames as possible. For instance if the hand intersects with the leg, begin by finding the frame where the intersection is at it’s greatest and set a key. Then find a frame either side of this “extreme” key where the arm is in the correct position and set a key on it. You should now have three keys, one in the middle representing the most extreme frame where the edit should happen and 2 either side representing the point in the animation where you want the arm to go back to it’s original position. Now you can go in and edit the animation on the “extreme” frame to remove the problem, while the other two keys will ensure the edit you make won’t affect the rest of the animation.
              • Check the animation. When you think you have finished all the editing, play through the animation to make sure you haven’t missed anything. View the animation from different angles and in different view-ports and try changing the playback speed, either in the Transport Controls or by using the jog control (holding down “j” move the mouse left to go forward or right to go backwards) to view the animation at different speeds. For smooth playback you will need to make sure you aren’t using “Play on Frames” or “Snap & Play on Frames” in the Transport Controls.

              • Plot the take to the Skeleton. When you are happy everything is look good plot the animation to your skeleton. In the Character Controls select Edit>Plot Character….>Skeleton.

              • Check the plot was successful. Play through the animation one last time and check everything is still looking good and that the animation has plotted correctly. Look for any errors you might have missed and everything is working as it should.
              • DO NOT RE-PLOT TO THE CONTROL RIG. If you need to go back and make any adjustments to the animation simply turn the control rig back on. If you Re-plot the animation to control rig you will loose all of your original key frames and permanently “plot” any errors in to the animation.
              • Save the file. Once you are happy with the animation all that remains is to save it out – oh and if your character appears to be moving in exactly the same way as it did when you first started this tutorial – check story is turned off..
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    How to Characterize your character in MotionBuilder

    May 29, 2010 4 comments

    This tutorial will guide you through the process of characterizing a model inside MotionBuilder. It will also help you create a custom Character Asset that can be used to quickly characterize other skeletons with the same joint names without having to use the default MotionBuilder naming convention. To allow you map animation and motion capture between characters and use MotionBuilder’s powerful animation features, you should characterize each new model so that MotionBuilder can recognize its structure. The main steps of this tutorial are:

    Importing a Character

    • Import your character in to MotionBuilder. If you are using MotionBuilder 2009 or above you will need to use File>FBX Plug-in Import… or File>FBX Plug-in Merge… to import your character. Pre MotionBuilder 2009 use the File>Import or File>Merge options. File>Import only allows you to specify which animations are imported, while File>Merge allows much more control over exactly what is merged in to the scene.
    • Scale the character. Depending on the unit scale you used to build your character, it may be necessary to scale it to the correct height inside MotionBuilder. Drag a locator into the scene from the Asset browser and parent the root of the skeleton, usually the hips, under it. The locator can also be used as part of the characterization set-up later on.

    T-Posing

    • Possibly the most important part of the whole process. It is definitely worth taking your time with this step to make sure everything is correct because it will seriously affect the rest of the your animation if it’s not.
    • Centre your character facing down the positive Z axis. Select the root of your character (the top joint of the skeleton hierarchy) and translate it to the centre of the scene and then rotate it so the character is facing down positive Z.
    • Rotate in to a T-Pose. Rotate the arms and fingers so they are straight and parallel to the ground. Rotate the legs so they are vertical and the feet are flat on the floor with the toes out straight.
    • The joints can remain slightly bent inside the mesh. The mesh itself should look as though the character is standing with it’s limbs perfectly straight.
    • Adjust the height of the character if necessary. If you have straightened the legs of your character you will need to correct it’s height so the feet are flat on the floor again.
    • MotionBuilder assumes all characters are characterized in exactly the same way. It uses this default “zero pose” to transfer animation from one character to another. Any deviation from this will create offsets during the mapping process which can result in characters having permanently bent knees or arms that rotate inside the body when they should be by the characters side.

    Automatically Characterizing a Character

    • Drag a Character asset on to your model.Drag a Character asset from the Asset Browser>Templates>Characters window on to your character. If the skeleton is named according to the naming conventions used in the Mapping list, MotionBuilder will recognizes which joint to add to the corresponding field in the Mapping List.

    Drag character Asset in to scene

    • Characterize and Select Character Type. Click Characterize from the pop up when you release the mouse button. Then Select the type of character you are characterizing from the dialogue box.
    • Rename the Character and Save. The characterization is now complete. All that remains is to set up the Floor Contacts, rename the character and save the scene ready to use.

    Rename character

    Setting the Mapping List

    • Create a Character and rename it. Drag a Character from the Asset Browser>Characters folder in to your scene. In the Navigator tab expand the Characters branch and right click on the newly created Character and rename it.
    • Open the Mapping List. Double click the new character in the Scene Browser to access the Character Definition Tab and expand the Base (required) group. Before MotionBuilder will allow you to Characterize your character you must complete all the fields in the Base (required) section of the Mapping List. These are the minimum joints MotionBuilder requires to create a control rig for animation or map data from another character. Many of the other fields in the Character Definition tab are optional but it is worth adding as many joints as possible from your character’s hierarchy to the Mapping List to get the best results from the Character set-up.

    Character Definition Tab

    • Drag the joints into the mapping list. Alt+drag the joints in to the appropriate filed from the Viewer, Schematic view or Scene Browser. The Mapping list creates a link between the joints in your character and a set of predefined nodes that exist in all characterized characters inside MotionBuilder. In other words it tells MotionBuilder which joint is the head, which is the leg, which is the arm and so on. All characterized characters inside MotionBuilder use this list of nodes to map animation and poses between characters. If you drag a joint in to the wrong filed you can simply re-drag it in to the correct field.
    • Add a Reference joint. You can use any object parented above your character joint hierarchy to put in the Reference field. MotionBuilder uses this node to translate, rotate and scale the entire character in the scene.
    • Leave Floor fields blank. Unless you need to define a specific floor height you can leave the Left and Right Hand and Foot Floor fields blank and MotionBuilder will use the grid, zero height, as the height of the floor. To define a specific floor height, create an object set to the required height and drag it in to the Floor fields.
    • Characterize the character. Once you have added all the joints you require to the Mapping List and checked the joint alignment one last time, click the Characterize box to active the character. MotionBuilder will then ask you to check the character is facing down the positive Z axis and what type of character you want to create. Click the correct character type and your character will be Characterized.

    Characterize

    • Re-Editing the Mapping List. If you need to edit the Mapping List you must put your character back in the T-Pose first. The easiest way to do this is to set the Character Settings>Input Type: to Stance and Activate it and deactivate it. Then disable the Characterization which will allow you to edit the fields in the Mapping List.
    • Adjust the Floor Contact Markers. Once the characterization is complete set up the feet and hand floor contact points if you intend to use automatic floor contacts. Make sure Floor Contacts is active in the Character Controls>Show… window. Use a side orthographic view to translates the markers to the heel, ball of the foot and end of the toes and use the front view to set the width of the markers under the feet.

    Creating a custom Character

    • Extract the Naming Template. In the Character Definitions tab click Extract Naming Template. This will populate the Naming Template column with the names of your joints. MotionBuilder will then use these joint names to recognise the joints in other skeletons with the same joint names.

    Extract naming template

    • Save the Custom Character. Once you have extracted the Naming Template select the character in Navigator tab and use File>Save Selected to create a file containing only the character.

    Save selection



    Using a Custom Character

    • Merge the Custom Character file in to a scene. To use the Custom Character in another file containing a character with the same joint names, simply File>Merge it in to the scene. Discard everything in the Merge Options window apart from the Characters Element to make sure nothing else is Merged into the scene.
    • Drag on to character and characterize. Drag the Character from the Navigator tab on to the new skeleton. Select Characterize from the pop-up window and either Biped or Quadruped from the Character pop-up box. MotionBuilder will automatically characterize your new character the same way it would if you had used the MotionBuilder joint naming convention.
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    Mapping Optical Data using MotionBuilder Actor

    May 13, 2010 1 comment

    In this tutorial I will show you how you can set-up the Actor to re-target motion capture data on to your character . Once the Actor is set up in this way it can be used to retarget optical data directly to your character either in real-time during a shoot for pre-viz purposes or after the shoot when you are ready to begin editing the data.

    Creating an Actor

    Import the marker data

    • The first step is to import a marker data file ( *.trc or *.c3d )  in to new MotionBuilder scene.
    • Ideally this file will contain the performer standing in a T-Pose with all the markers identified and any errors corrected.
    • In the options box tick Create Optical Segments and un-tick Create Unused Optical Segments as the Unused Optical Segments aren’t required and will only confuse your scene.

    Import Options

    Create an Actor and re-name it

    • Drag an Actor in to your scene from the Asset Browser>Characters folder and rename it to something more useful. I usually use the performer’s name I’m doing the set up for so it is easy to find the corresponding Actor in the scene if I need to change something. I also include anything special about the set up like a day number or costume type.
    • If you are going to have multiple actors in your scene for live previz you can be very flashy and change the colour of the Actor in the Properties>Actor Settings>Body Colour tab.
    • It may take a little more time to set up your scene this way, especially if you are under pressure to get a scene ready, but naming everything in your scene can save you a lot of time and pain later.

    Drag in an Actor

    Aligning an Actor

    Align the Actor’s hips to the waist markers

    • Select the hips of the Actor and align them with the hip markers in the scene making sure the Actor is facing the right direction.
    • Space-bar>Right-Click the hips of the Actor to select the all the body segments and uniformly scale them to best fit the marker cloud.

    Align the Actor

    Align the rest of the Actors limbs

    • It is helpful to have reference showing where the markers were placed on the performer so you can align the Actors limbs to match. Ideally you would have photos of the performer in their T-Pose for this or, if you are doing a set-up for live pre-viz, you can simply look at the performer in front of you.
    • Scale each of the Actors limbs to match the performers limbs using the markers as a guide.
    • When aligning the arms be aware that people usually lift their shoulders slightly when they raise their arms into a T-Pose. If you don’t replicate this on the Actor it will cause your characters shoulders to droop when they put their arms down.
    • As a rough guide, I usually rotate the “Collar” segments up by about 10 degrees at this stage and then fine tune them later during an action where the performer has their arms down by their side.
    • Each limb can then be  rotated in to place or you can turn on the Character Controls>Actor Controls>Edit>IK Manip and drag the segments in to place.
    • The IK Manip allows you to use pinning to lock body segments in place while you are adjusting other body parts. It also allows you to lock the rotation of segments like the feet, so they remain flat on the floor when dragging them in to position.

    Actor IK Manip

    Locally rotate the “Shoulders” by 20 degrees

    • One thing sometimes missed when aligning the Actors arms is that if you put your arms straight out they very rarely match the default angle of the Actors arms. Instead of being angled with the elbow pointing backwards, they are often angled with the elbow pointing slightly down by about 20 degrees.
    • Always check this alignment using the marker positions as a guide.

    Assigning marker to an Actor

    • Create a marker set. In the Actor Settings tab click the Marker Set… button and select Create from the drop down menu. You should see circles containing zeros appear over the Actor picture which you will Alt-drag the markers in to. MotionBuilder uses the markers you drag in to the cells to calculate the movement of the associated Actor segments.

    Create Marker Set...

    • Drag the markers into the Actor’s Body cells. It may require a little experimentation with the marker assignments to get the best solution for your marker set up.
    • If you change your Viewer to X-ray mode ( ctrl+a ) and turn off the Actors skeleton, it makes it easy to drag select multiple markers without selecting the Actor segments.
    • Make sure you don’t accidentally select the wrong markers when dragging or forget to clear your selection before adding more to it.
    • If you add a wrong marker to a cell simply select the cell and delete the offending marker from the left hand column.

    Removing a Marker

    • I usually drag the wrist and hand markers into the hand cells and the ankle and foot markers in to the foot cells leaving the wrist and ankle cells empty.
    • Once you have filled all the cells and checked the alignment of your Actor to the markers simply click Active to activate the mapping.
    • You can check the quality of the mapping by scrubbing along the time line or by hitting Play, to see how well the marker data is being solved to the Actor.
    • If some of the Actor’s limbs don’t appear to be behaving correctly you can refine their positions while the marker set is still active.
    • Once you are happy with the set up, save the file as something easily recognisable like the performers name plus the date.
    • I would recommend creating a new set up file every time the performer removes their suit or the marker set-up changes as any changes in a markers positions will affect the way the data is interpreted by the Actor.

    Importing New Takes

    • Select the Optical Root. This will appear as a wire frame sphere at the centre of the scene. You must be in a camera view with “Model Only” mode turned off) It is also the top node or parent of the group of optical markers in the Schematic View or in Navigator>>Opticals.
    • Import Files. Using File>>Import… select individual or shift/ctrl select multiple files to import. I would recomend only importing files captured on the same actor and the same day as the file used to create the Actor set-up.
      • Merge: In Selected Hierarchy. Select the Merge: radio button and then change the drop down menu to In Selected Hierarchy.
      • Turn OFF create unmatched model
      • Turn OFF Create unmatched optical segements as you shouldn’t need these in the scene.
      • Turn ON Create Optical Segments
    • Click import. You may get a warning saying that MotionBuilder couldn’t match all the model in the scene. This shouldn’t be a problem if your data has been clenaed and all unidentified markers rectified correctly.

    Import Optical Data Settings

    Map the data to your character

    • File>Merge your character in to the scene.
    • Change your character’s Input Type: to Actor Input and change the Input Source: to the Actor and tick Active.
    • You may need to adjust the various re-targeting options in the Character Settings tab depending on the difference between the proportions of the performer and your character.
    • The positions of the Actor segments relative to the markers may also require small adjustments each time you import a new take.

    This Actor Set-Up can also be used to stream live data from a capture system directly on to your character in real-time – but I shall save that for another post…..

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