Preparing a Model for CrowdFX

 
 
 

CrowdFX is designed to be used with any type of rigged polygon mesh envelope in a model that has action sources. This model is known as an actor when used in CrowdFX. With typical crowd scenes, these actors are usually bipeds or quadrupeds, but you aren't limited to that.

Of course, there are some requirements for the model and its animation that need to be met before you can use it as an actor in CrowdFX.

Model

Envelopes

Rigs

The character or polygon mesh object needs a rig that deforms the envelope. Consider the following issues for it:

Action Sources

Locomotion-type animation stored in the action source must be moving in global space.

If the action is in global space, it needs to be moving in the positive Z direction, such as a walk cycle going forward. This allows CrowdFX to immediately compute the ideal speed for any locomotion in the crowd simulation. The velocity used for each action source in the simulation is calculated based on the horizontal speed of the character's COG deformer.

Materials and Textures

Make sure that the correct material is applied to the character's envelope object, or to multiple clusters on the envelope mesh. The materials on the clusters are converted to ICE Materials on the actor when it's imported into CrowdFX. See Modifying the Actor's Materials and Textures for information.

Importing Models for CrowdFX

In addition to the CrowdFX requirements listed above, here are some tips for importing a model from another 3D software, such as Autodesk Maya.

The FBX file format is the most typical and stable format for importing models into Softimage. You can import a first FBX file to get the character (mesh and rig), and then import other FBX files with the same rig but different animations.

For each imported animation, select the Import as Action Source option on the Import tab in the Import FBX Options Dialog Box to add only the animation as an action source. Then on the Animation tab, select the Take you want to import (you can import only one take at a time). Make sure to deselect the Skeleton and Envelope options on this tab so you don't import the rig again when you just want the animation.

If the model uses several meshes, use the Create Poly Mesh Merge command on the Model toolbar command to create only one mesh, as described in the Envelopes section above.

Be aware that the scale of Maya models is often quite a lot larger than the standard default size of characters in Softimage. Make sure to set the scale accordingly in the Import FBX Options dialog box; for example, use Decimeters as the unit of scale. You can also parent the whole model to a null, and then scale down that null to match other characters you're using in CrowdFX.

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