3DS Max 9 Flickering Final Render

The only thing that seems to be too low is the FG Point Density.  I'm sure that you guys are trying to keep your render times low but fewer points will certainly result in a lower quality rendering.

Have you done a FG diagnostic before?  If not, click on the Processing tab in the Render Setup dialog box.  In the Diagnostics section, check Enable and choose Final Gather from the available options.  Then render the scene.  Your final render will show in green all of your final gather points.  

You should find very few FG points on the walls and other large surfaces (where most of the flicker is visible) compared to the more detailed areas - which is normal, but with a point density of .4, you'll only see 40% of the points than would normally be placed for a FG calculation.  Each point is probably shooting enough rays with a setting of 150, you just need more points for better accuracy frame to frame.  

You might even be able to lower your rays per point significantly (as long as you have enough points) to compensate for increased rendering time.

Increasing Interpolate Over Number of Points will also help to even out the lighting produced by FG (maybe 50 or so).

Another option is to calculate an FG map over a number of frames and then lock the map for use in your final render (as long as you don't lock a 1-frame FG map).  This link has a good overview of the process.

Hope this is helpful. Good luck!

Very interesting.  Could this be an exposure problem?  Are you rendering with any exposure options other than logarithmic?  If so, that could be your problem - and it would certainly cause this.

I'm not sure what techniques you are using to troubleshoot, but I would do the following:

1. On a single machine, hide everything in your scene except the walls, floor, and ceiling (and maybe place a simple box or two in the scene to represent your shelving.  Everything should now render very fast for testing purposes.

2. Turn off GI and FG and render a test animation - just to make sure that your lights aren't flickering without indirect illumination. If you get flicker, then look to your light sources or perhaps your MR render settings (special camera shaders or effects).

3. Turn on FG with no FG map (try settings of .8 - 1.0 density, 100 or so rays, 30 or so interpolation, 0 bounces.  Render and animation and check for flicker.  If you get flicker, try making adjustments to these settings to fix the flicker (higher rays, point density, etc.) - If you still have flicker, I'd question possible file stability or some random render setting.  I've fixed some strange rendering issues just by switching to scanline and then back to mental ray.

4. If you rendering is good to this point, I'd try creating the fg map every few frames of the animation and then render the sequence.  If you have flicker, I'd question the fg map creation technique.

5. Next, turn on GI and test again with a new fg map.  If you get flicker, you can work with the GI settings to fix.

6. If all is good to this point, try a backburner rendering with the simple scene.  If you get flicker, make sure the FG map is being loaded by the other machines.


Other things to consider:
1. Are you using any rendering effects (Environment-Effects) or plugins that could be affecting the rendering.
2. Are there any animated materials that could be affecting lighting.
3. Are any aspects of the lights animated or use any animated maps
4. If area lights - are you using enough samples?
5. Is it possible that a light is too close to the ceiling - resulting in z-fighting...some frames the light emits, some frames don't.  z-fighting is pretty random.
6. Maybe try merging all scene geometry into a fresh max file.

Out of ideas. :)  I'd be happy to take a look at your max file but I'm sure you'd rather not send that out.

Good luck.

Ha.  Yes, always something to fix in Max. :)  

If you decide to use exposure controls with your animation, Logarithmic is the only one you are supposed to use - as it is the only one that will produce consistent lighting from frame to frame.  I am not a big fan of it though and avoid exposure controls when possible.

By the way, the term z-fighting refers to the artifacts you see when 2 polygons share the exact same local z coordinate.  Which one gets rendered?  Since one may render on one frame and the other on another frame, we think of the polygons as fighting each other for rendering control.  

Lights can also share the same local z coordinate with polygons and the same issue can occur.  So, after I place my lights (autogrid or snapping), I always nudge them down from the ceiling a fraction of an inch as to avoid z-fighting.

I certainly feel your pain on this one as I have been in a similar situation more times than I care to remember.  Nice scene by the way.  You guys are very talented.

Good luck.