V-Ray RT 3.0 CPU mapping issue.

[wyszolmirski]

Hey,

With the changes in 3.0 I hoped that finally we would be able to use it for extensive shaders testing. Especially after reading this in changelog:
(*) V-Ray RT CPU: Internally uses the production renderer core running in progressive mode;

But the thing that bothers me a lot is mapping of 3d maps (set to either World, or Object) in RT vs ADV:

On the left RT, right 3.0 production renderer. Scale seems correct. But it has this wrong offset.





Bercon maps are totally wrong.

Is there anything that could be done to make it accurate ?

Best regards,

Tomasz.

[vlado]

The RT now uses the same core algorithm as the production renderer; like it says in the changelog this allows us to render the new skin shader, the sss2 material and other useful features in the future like the environment fog and eventually to support light cache, irradiance map etc. Also, the results are much closer to the regular production renderer.

However, this does not mean that the production V-Ray for 3ds Max renderer works in RT mode. The scene is still translated to V-Ray plugins, and it is V-Ray Standalone that renders the scene. As such, it doesn't use the 3ds Max procedural textures; instead it uses our implementations, which generally produce a different noise pattern. The same goes for the Bercon maps where some functionality is not implemented as a V-Ray shader yet.

If you are wondering why we don't just use the normal V-Ray renderer in RT mode (and I myself would love it if it was technically possible), there are two main reasons:

1. Stability. Doing changes to the scene while a renderer is working on it in 3ds Max (sometimes even just saving the scene) may cause crashes or other unexpected results; other renderers have attempted to do that and could never work around the various crashes and issues that follow from that.

2. We cannot get DR for RT to work in any other way and this has proven to be a popular and useful feature.

Best regards,
Vlado

[wyszolmirski]

At least now I know what to keep in mind while working with RT. Thanks for thorough explanation.