IR prepass even after saving/loading the IR maps from file??

[digitalx3d]

It's been awhile since I've done much animation. I'm using Vray 2.3 still and seeing something I don't remember from past experience. I've prerendered the irradiance map and light cache and saved them to file. And now that I'm rendering out the frames, at the start of each frame Vray does a really quick prepass. It only takes a second or two, so at first I didn't really care. But in one of my scenes, it started Max started crashing during the prepass of the 2nd frame. So now I'm a bit concerned as to why it's doing this prepass. I'm trying to troubleshoot it now, and at the moment am rendering out frames with an Override material (just a default VrayMtl) and it seems to be doing just fine... even the DR slaves are kicking in right away... all looks good. It is still doing the prepass, so maybe that's not the issue. Though I'd still like to know if this is normal or if I've got a button switched somewhere that's causing this. At first I thought it was an reflection/refraction Interpolation setting in one of the materials. I wrote up a little script to check all the scene materials for this and that turned up empty, so I'm pretty sure that's not the case. But now, seeing as it's rendering fine with the override material, I'm guessing maybe there is a corrupt material or texture somewhere. I'll report back once I figure this out, but can anyone shed light on the Prepass?? I just seem to remember that when rendering from file it just went straight to ray tracing.

Thanks!

[digitalx3d]

ok, well a couple hours later I think I've solved the problem(s). So the extra prepass was definitely being caused by a VrayFastSSS2 material which was a submaterial in the grass I was using. (The grass that comes included with Forest Pack Pro). I had to remove that from the "template" material AND from the Forest object material AND I had to actually delete the SSS material from Slate Mtl Editor. After I did that the prepass disappeared.

The second issue was the crashing on the 2nd frame. Turned out this was not related to the SSS material, but what fixed this was limiting the grass distribution to the Camera field of view. (I'm not sure why I didn't have that checked anyway... though in this animation I'm hoping that doesn't bite me in the a$$ and show up in a reflection somewhere!) Once checking that option, everything renders ok!

As for how I narrowed it down to the grass... the first thing I did was disable an XRef file with 100 or so cars in it, and then turn off ALL the Forest Pro objects. Rendered fine, no prepass. Turned the cars on.... rendered fine, no prepass. Turned the cars off, ran through the 3 Forest layers one at a time- Trees... rendered fine, no prepass. Grass... PREPASS and crash! Shrubs... rendered fine, no prepass. There ya go... back to being productive!!

[svetlozar.draganov]

Glad to hear you sorted it out.
Let us know if something unusual happened again.