Jerky Motion Path Animation

[indestructibleman]

i'm animating a cart going down a hill on a motion path. the curve is on the surface.

the scene is big enough that the uValue is only changing by about 0.001 a frame.

occasionally, the object will move backwards for one frame. which is to say, 0.058 is further down the curve than 0.059.

i could animate around this by having it go in one frame from 0.58 to 0.61 or something like that, but my wheel rotation is driven by the uValue and my spokes jump.

other times, three frames in a row, with uValues of say, .206, .207, .208 will show no motion whatsoever, then .209 is a big jump.

the hangups always seem to be near CVs. if i rebuild and reduce the number of CVs it still hangs up near the CVs.

any suggestions?

[joojaa]

post a rudimrtary scene in .ma format that demostrates the problem.

[indestructibleman]

http://flavoroftheweak.com/stuff/shot001v093crvproblem.ma

the file is about 2mb.

you can see that between frames 24 and 25, the circle moves backwards. it also does this in frames 58-59. in frames 92-95 it doesn't move at all.

[indestructibleman]

ok, i think the problem is that i'm using 1/1000th increments, which is what Maya rounds everything to.

i've found out that you can set your uValue on the motionPath to a range matching the parameterization of the curve.

so i've rebuilt the curve to have 100 uniform spans. now my uValue goes from 0 to 100 instead of 0 to 1. so now my increments are roughly 1/10th per frame and i don't seem to be getting my original problem.

[joojaa]

Maya does not internaly round stuff to thgose increments just your gui. So if its somethink keyed trough yoru gui then its that but if not then its definitevely not that.

[drblacksnake]

enable parametricLenght switch