VRayMat Glossy Reflections but Env map reflection is sharp

[alexyork]

Hi folks,

I've long struggled with this one. If I have a reflective vraymat with, say, 0.5 glossiness value, it reflects objects in the scene nice and blurry as expected. But if I'm using a map in the environment or reflection override (a sharp photo in this example) it will be reflected pin sharp in the material. Therefore we can say that the glossiness of the material is ignored when it comes to the reflective environment/override.

Is this correct? It seems it can't be right. Is there a param somewhere to change this behaviour? At the moment my workaround is to use a custom version of the same BG photo map that has a blur value of around 60 for the reflection override, and it looks suitably blurry in the glossy material. But this is naturally not physically correct and clunky.

Thanks,

[matanov]

Everything is fine in my tests. Can you upload/send a simple scene ? What version are you using ?

[alexyork]

Everything is fine in my tests. Can you upload/send a simple scene ? What version are you using ?

I'm using the latest stable build but I've had this in many other versions as well. I might try to pack up a simplified version of the scene but it's an extremely sensitive project. I might try to make a new scene from scratch that has the same issue.

[alexyork]

I have discovered the issue - using Screen Mapping for the Environment map, in this case a photo. We use this mode all the time when doing photo-montages. I guess the work-around would be to use a spherical or cylindrical version of the same photo in the Reflection Override slot, but this means a lot of extra work. Would it not be possible to have vray properly interpret a Screen Mapped map for this purpose?

[matanov]

Aaaah I see - this is not a bug. Its hard to explain (for me) , but that is the way raytracing work in case of Screen mapping. I will try to write you an explanation later.

[alexyork]

Thank you - I thought that might be the case, although I do hope there might be a workaround for this that doesn't involve using different maps. My feeling is that if a material is glossy it should reflect everything glossy in the same fashion, as you'd expect in reality.

[matanov]

I promise you that you can't reproduce the "Screen mapping" scenario in reality In this case you have no environment for your objects to reflect/refract. All there is is the background image which is projected straight through from the camera, so all your reflections/refractions are projected in the same manner which is why your glossy material looks sharp (its actually appearing transparent).

[alexyork]

This makes sense. I think the only solution, then, is to have a custom version of the map that is blurred or converted for spherical/cylindrical mapping.

Thanks,

[matanov]

Yes - stick to the more "realistic" environments for best results