RT picture different from final render

[TheLooopCGI]

We are a little bit concerned with RT at the moment. We found out that what we see in RT is usually not the same in the final render. Our biggest concern is with the lighting as we sometimes need more power for the lights in the final render than what we needed when we setup the scene with RT.

I'm attaching two comparison images. The red arrows pinpoint the differences. As you can see the licence plate has a different lighting as well as the ground at the right edge of the picture. Also the reflections of the strip lights on the car is not the same and the headlight has a different light.

We checked with the list of unsupported features and we don't use anything which could cause a problem.

The scene contains a few standard spotlights and a few VRay planar lights.

Any idea what could be wrong?

Thanks!
David

[vlado]

Not sure right away, but if you can send just the different parts to me at vlado@chaosgroup.com I will be able to tell you more.

Best regards,
Vlado

[TheLooopCGI]

Okay, I sent you an email.

[TheLooopCGI]

Anything new on the matter?

Thanks.

[TheLooopCGI]

I'm sorry Vlado, but we would like to have some kind of answer on this. Unfortunately it's not the only image where we had problems like that so at the moment we can't use RT at all.

It would help if we knew what is the problem so we could either fix our scenes or don't use a particular problematic setting/light/object until there is a patch for RT - if there is needed one.

[vlado]

As far as the different lights are concerned, this is because they are flipped along the Y axis; the production V-Ray does not seem to like that and renders the light on the wrong side, whereas V-Ray RT renders it correctly.

Distributed rendering works fine with the textures here, but you can look at the console output from the render server to see if it failed to load some textures.

You did not include some of the other problematic pieces of geometry on the side of the car in the scene, so I'm not sure what goes on there.

Best regards,
Vlado

[TheLooopCGI]

Oh I see. Yes I mirrored those lights from the other side of the car. I didn't know it could cause a problem for the renderer! Is there a way how to make them un-flipped? Or do I need to re-create those lights for new ones?

As for the side of the car - the problem was only a texture not loaded - I'll try to play with some settings and file paths.

There was also a different light inside a headlight. The reflection looks quite different. Would you know what's wrong?

Thanks a lot for the support,
David

[vlado]

Oh I see. Yes I mirrored those lights from the other side of the car. I didn't know it could cause a problem for the renderer! Is there a way how to make them un-flipped? Or do I need to re-create those lights for new ones?

Just revert the Y scale to 100% and rotate them 180 degrees instead in local space.

There was also a different light inside a headlight. The reflection looks quite different. Would you know what's wrong?

This seems to have been because of the flipped lights.

Best regards,
Vlado

[TheLooopCGI]

Ah okay. Thanks!