Brian,

After checking out your sample file, there were a couple of things going on, both of which were easily correctable.

First, Anything Grows did recalculate once in the animation. It happened when the renderer changed the level of detail on the spline object as it got closer. Far away it created a low level of detail object, closer, it upped the LOD so the edges would stay smooth. Changing the level of detail setting on the spline object, by selecting Geometry|Surface Fidelity while in the spline modeler, to 5000 fixed that problem. It forced it to stay high all the time even when it was far from the camera.

The second issue was sample rate for the renderer. When you were far away, some of the stuff in shadow would appear and disappear. The strands themselves were big enough to be picked up in each frame, but some of the partially illuminated strands would slide in and out between the renderer's lightrays as the camera moved. To fix this problem kick up the AntiAliasing to Best. When set on Best, information from a much higher sampling rate is introduced into the image and those partially illuminated strands show up on every frame.

As I checked into the modifier/spline object thing, I remembered why I didn't do that in the first place. Most of the modifiers change the number of facets as they animate the object. With a different number of facets, I have no way of keeping the strands in the same relative place from frame to frame so as the underlying mesh changes, the distribution of the strands changes. Bones on the other hand do not change the number or order of the facets so I can go back to the original unboned mesh to calculate distribution of the strands, length, width, start direction, etc. and then use the facet's actual position to calculate start position, modify the direction, and gravity.

Best regards,
Eric Winemiller
Digital Carvers Guild
3D extensions for Carrara
http://digitalcarversguild.com

Eric Winemiller
Digital Carvers Guild
Carrara and LightWave plug-ins