light cache problems

[alkis]

dear all
i ve been having some problems in the past few days with the light cache
i m precalculating a scene for animation (3000 frames)
i ve split the length in two so it can be computed at the same time from two machines.
frames 0-1500 were precalculated fine
frames 1500-3000 seem to have a problem
the light cache reaches 98 % and then stops
the cpu is working only at 50% and it s been like that for a day now
i ve resent the job to another node with slightly lower settings and its doing exaclty the same thing

some info on the scene
primary IRMAP
second LCACHE

1500 samples
sample size 0.02 , screenspace
flythrough mode
use lcache for glossies on
everything else default in lcache settings
vray 1.47.03
xp, max8 sp1, dual xeons 3.2 ,3gb switch enabled

any ideas would be greatly appreciated
regards
alkis

[vlado]

Do you have any transparent or pure white materials? Any standard materials? Shellac/Blend/Composite materials (anything other than VRay materials, in fact)?

Best regards,
Vlado

[alkis]

i only have standard and vray materials
most of the standard ones have just a texture on the diffuse slot
there are a couple of standards with no textures but none with pure whites
there are also a couple of transparent standards
the strange thing is that the precalc for the same camera worked perfect for the first half of the frames (0-1500) but hangs on the second part.
by the way is there a chance that the lcache is calculated for the entire range of frames of the camera rather than the selected ones only?

thanks for all the help
regards
alkis

[vlado]

Well, it would be best to avoid the standard materials altogether; since they are simple diffuse ones, the conversion should be easy enough.

If you set the light cache mode to "fly-through", it will be calculated for the entire animation.

Best regards,
Vlado

[Candelero]

@ alkis

Try overriding the scene with a simple VRayMtl. Let it go for some (10-15 frames) in the second part of the animation. If it is working ok, so there are
probably some material issues.

Best regards,
nikki Candelero

[alkis]

Thanks a million for the replies
i ve converted all the materials last night to vray mats and it worked perfect.
the strange thing is that i left the old precalc job running just to see what happens and this morning after 3 days it finished the lightcahce!!!!.
however , backburner only showed that the first frame where the lilghtcache is calculated took only 5 hours instead of the 3days (however many hours is that).
bizarre
very bizarre indeed
thanks again for all the help
regards
alkis

[Nixon]

mmm

The same thing happened to me with a scene that had a few frames with very bright glossy highlights for a few frames. The problem got even stranger, because it appeared in only frame 250 from a 500 frames animation.

After a lot of testing (3 days) I figured that a specific frame the light cache creates samples that get somehow too complex (too bright) to figure out. The issue came with any machine (Dual, AMD, Xeon, etc) I had tested it with.

The temporary solution was to significantly lower the samples for a small part of the whole animation so that at some point those "bad" won't be calculated.

The final solution was to change the lighting in the scene, so that it wouldn't have that kind of overbright areas. The LC rendered with no problem on any machine after that.