Step 1: Load Mocap Data
Load the actor’s ROM (range of motion) file into BLADE and open the Face Retarget Setup window from the FacePro custom tools. Scrub the time bar to find a frame where the actor’s face pose is the same as the character’s neutral pose. Set the Actor Prep Tools droplist to neutral and press Save Actor Pose to save this information to the configuration.
Step 2: Load Character Assets
Next, load your character assets into BLADE. This may have been exported from Maya using ViconGPMaya or imported via the BLADE FBX Importer. Use the character’s top hierarchy node to move it so it is side’ by’ side with the actor markers. This will make it easier to compare the faces during the setup process.
Step 3 Select Alignment Markers
First, you need to define how the actor’s and character’s faces orient to one other during retargeting. The markers you choose should have equivalent facial locations, such as the corners of the mouth or eyes. Select some perimeter markers near the ears to help with the alignment. Save your selection by pressing the Set Retarget Align Markers button in the Mapping Tools section after you’ve selected your markers.
Step 4 Retarget Types
FacePro can animate your character in two ways: point retarget and solve retarget. Point retarget is for nodes that have translations as their primary form of animation. Solve retarget is for nodes that have rotations as their primary form of animation. For example, forehead nodes are often translated ( point retarget), whereas a jaw would actually rotate ( solve retarget). We’ll map our point nodes first.
Step 5 Map Point Retarget Nodes
Select each point node of the character and the corresponding marker on the actor’s face. For example, match the left eye inside corners, left nostrils, end of nose, and forhead nodes. Select the pairs one at a time. Press the Add Trans button in the Point Retarget” section to save the mapping. Repeat this step for all of the character’s point retarget nodes.
Step 6 Map "Skin Flex" Groups
Point retarget nodes have an optional secondary retarget feature. Skin Flex orientation lets us calculate how the markers (and the skin they are attached to) subtly rotate as the face moves- even though the mocap system doesn’t capture this rotation directly. This is particularly useful in the lip area, where the "roll" of the lips is as important as how the markers translate.
To set up Skin Flex, choose a marker that you point-mapped to the character. We’ll call this our target marker. Select the markers surrounding the target that define its orientation (think of it like a vertex and its surrounding vertices). Add select the target marker and press the Add Orient button to save this mapping. Repeat for all point-mapped markers.
Step 7 Map Solve Nodes
Select the “jaw” bone and the markers to define the jaw motion. Usually, several markers around the chin work best. Press the Add Rot button in the Solve Retarget section to save these.
Step 8 Set Scale Control Nodes
The actor’s face will need to be scaled to match the size of the character’s face. You’ll need to select pairs of markers to define each axis during the retarget. In this setup, we’ll use the corners of the mouth for the width. Select the right and left corner mouth markers and press the X Targets button in the Set Auto Scale Targets section. Next, use a corner of the mouth and the inner eye corner for the Y Targets, and the tip of the nose and an ear marker for the Z Targets.
Step 9 Test the Retarget
That’s it. You can clear your scene and load a motion file to test the retarget by running the "DCG_auto_retarget_sample" pipeline.
Tools Used: Vicon BLADE 1.1, Digital Concepts Group FacePro 1.0, BLADE FBX Importer, Autodesk Maya, ViconGPMaya
The Digital Concepts Group
The Digital Concepts Group develops innovative digital technology for the next generation of digital animation, filmmaking and visual effects. As co-founder, DJ Hauck brings a wealth of expertise in developing custom digital solutions for complex filmmaking challenges. With his extensive knowledge of technical setups and 10 years of experience in the development and implementation of motion capture, DJ has provided innovative pipeline approaches for film projects including Beowulf, Monster House and The Polar Express.
DJ Says Keep in Mind…
DCG FacePro v1.0, aimed at both the novice and experienced mocap user, is a customizable facial motion-capture plug-in designed for the Vicon BLADE system. If you have facial motion capture from an actor that you need to apply to your CG character- and unless your actor and character have the same face- you’ll have to transform this motion by retargeting it. Throughout the entire mocap process, be practical when capturing your data. You can always tweak a performance in post, but it’s worth it to spend the extra time during your capture to make sure you get the best performance and data possible. It will almost always save you time and headaches later.
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