IPR / Production Render Reflection Discrepancy

[lukeRFH]

Hi All,

I've been working on a project that involves a car on a glossy floor. I've been using IPR to tweak the shaders to my liking and rendering full res at night. I recently ran into an issue. My renders were not matching up to what I had seen in while working in IPR. It's a relatively small issue but large enough to give me pause.

In the render regions I have attached (IPR on the left, production on the right) you can see that the IPR region seems to reflect the strong highlight on the red car and the production render does not. There are also a few other small reflection differences. (The materials on the car are just stand ins while I focus on the floor)

I am using CPU for both. I am using Vray 4.04.02. Thinking it was some sort of caustic or BF/LC issue I disabled GI completely but still got the same result. I was using the bucket sampler type so I switched it to progressive. Same result. It definitely seems to be a reflection issue because that highlight only affects the reflection pass.

Anyone have any ideas?? Let me know if you need any other info.

Thanks!

[Zdravko.Keremidchiev]

This seems odd, I can't reproduce it in here. Can you attach or send us an example scene with a stripped version of the scene that we can test?

[lukeRFH]

I just did a little more testing and I believe I found the issue.

Because I brought the geometry in from another application Maya applied a Maya phong material. I didn't give it much thought because I was only focusing on the environment and not the car. I did a test where I replicated the phong material in a VrayMtl. When I do this the IPR and production render are the same.

I was able to recreate this in a simple scene and have attached the result. Production render on the left, IPR on the right. The sphere is a Maya phong and the ground is a VrayMtl with no diffuse color and an IOR of 10. A simplex noise is plugged into the reflection glossiness. The scene is lit with a Vray sun and sky.

The good thing is it looks like this only happens when using a Maya phong material, which is not something most people use (or should be using).

Let me know if you have any other questions.

[Zdravko.Keremidchiev]

It seems the Specular color of the Phong is not reflected correctly with the production renderer. I'll make a note about that. Thank you for the update.