I did do a search but it seems Im getting some conflicting advice. I also read some of the metal ray help within Maya.. but its not too descriptive it seems. Maybe this topic should be explained and become sticky in this forum.
(Im using Maya7)
So I have a simple animation of a logo, where the camera pans across the logo along the X plane. Like a simple logo pan... right to left. I also have the logo spinning 360. So the camera is panning and the logo is rotating.
Well the logo is doing the infamous flickering shadows. I understand that FG has to recompute each frame, which can cause inconstant lighting/shadowing, if not set up properly. Then I was reading where you have to specify a FG map for caching and you render a few frames in the timeline for "lookup"... then I found out there was a default FG map already.
My questions are...
If there is no file name in the FG file box, does it use the default.fgmap?
By rendering a few frames on the timeline, are you creating a "tween" like effect for the FG Rays? Then this info is written to the *.fgmap, so FG has "markers" to "tween" the rays to get them to look more consistant? Does it matter what order you render a few frames in?
If there is no animation in the scene, but the camera itself... you should turn rebuild FG off? Can someone explain the 3 different rebuild modes?
If I made some adjustment to the FG settings, after a few look up renders, do I have to rerender the same frames for lookup, rename the file to a new file or delete the *.fgmap from the folder so it writes a new one? Im a little cloudy on whats going on with the FG file.. maybe someone can elaborate on the process.
I noticed the biggest difference is when I bumped up my FG rays and adjusted the min/max radius with FC rebuild set to off, for this particular scene. What I think I figured out is no matter what you set you map to, every frame FG computes is gonna be a bit different, since its all based off the rays.. kinda like resoultion... it has to "draw" the rays each frame which will give you some artifacts, regardless. SO the question is... am I right? And bumping up they rays is like increasing your resolution of the FG rendering.. which makes it appear to be more subtle?
Sorry for the questions but I am a newby to FG and maybe this might help a few other newbies 
AMV