Black objects with animation prepass

[Nickh]

Hi,

I have searched around and cant find an answer to this.

We have a bit of an emergency on, and appreciate any help....

We have a scene with lots of things moving, and about 3500 frames to render, so animation prepass is only answer. However random objects (which seem ok, and render fine on single frame irr\lc\brute and multi-frame too) are rendering completely black.

They do originate from revit, is one possible culprit. But there are a lot of objects, and all animated so would really like to fix this in the render settings if poss.

Many thanks
Cheers
Nick

[Nickh]

This appears to be related with transform keys - anything with them renders black.

Has anyone else had this?

[tooves]

We are having this problem on some of our shots. It seems like it may be connected to the "use camera path" tickbox but the error does not happen consistently, so it is hard to troubleshoot.

[bernhard]

interesting ... I realized same issues... couldn't tell what caused it.. but I figured out it was wrong GI calculation... and I used "Use Camera Path" as well... anyone out there who knows more about that ?

[Morbid Angel]

Could they have flipped/bad normals? Can you check one object in question for that?

[bernhard]

yeah.. was my first thought.. did that.. renders fine without prepass.. normals are ok, it just appears after the prepass calculation.. something goes wrong when calculating the GI.... the question is: what ?

[Morbid Angel]

yeah.. was my first thought.. did that.. renders fine without prepass.. normals are ok, it just appears after the prepass calculation.. something goes wrong when calculating the GI.... the question is: what ?

did you try simplifying the scene like select object that is black hide everything else, render it with grey material etc? Often times though normals appear ok they may not be; you may have a case where the normals are locked and their smoothing information is destroyed (by exporter) this happened at one point a lot with fbx.
Try shelling the geo and see if there is any difference or convert it to another type of mesh.

You can also check if the object is excluded from gi in vray properties. Lastly you can post this object here perhaps we can have a look.

[Svetlozar Draganov]

Is it possible to provide us with a sample scene for testing ?
Thank you very much in advance.