creating a corona style mapping of domelight

[matthew999]

Hello,

I know that corona has a few visually pleasing mapping techniques for dome lights where you can define the size of the dome where as vrays mapping is always infinate. I saw lele mention that is should be easily recreatable with shaders and geometry in vray so there is no need to impliment it within vray.

Ideally i would like to use this technique for just quick pre vis renders to check shaders are correct with client etc etc, so i would like this effect to be visible only in primary rays and refraction. However it seems that as soon as i enable this geom visible in refraction it also needs to be visible in reflections and consequently it changes the brightness of materials etc which is not ideal.

the render below is vray domelight mapping



the render below is using custom geom with spherical projection, the geom is set to prim vis only, u can see the vray projection mapping through the green glass which is not ideal



the render below i have ticked visible in refractions on the custom geom to, note how it kills the reflective/specular qualities of the red sphere, but the refraction is now good


the render below i have now enabled visible in primary, reflection and refraction on the custom geom but it has changed the intensities of the glossy reflection/spec on the red sphere.


Is there a way just to have this envronmental geom vis in refraction but not effect the speculars etc, i dont want to have to compensate all shaders for the dullness created in image 4.

Link to test scene below

https://www.dropbox.com/s/7tyop437ny..._test.zip?dl=0


thanks in advance

Matt

[hermit.crab]

Make the VRayDome invisible and set a Refraction Environment override (Render Settings>Overrides>Environment) with the same projection node as the artificial dome.

[matthew999]

Hi Hermit Crab,

Thanks for your help but im not sure it is a solution though. I cant assign a maya projection node to the environment slot and when i assign the texture swatch with the hdri is adds a VRayPlaceEnvTex which breaks the seamless mapping between floor and background. see attached

before


after


any fruther suggestions?

thanks in advance

Matt

[hermit.crab]

Wouldn't it be easier to set the "floor" as a matte (shadow catcher) and use the HDRI as a Background override?

[matthew999]

Hi Hermit Crab,
Sorry I'm not sure you understand what I'm asking. My question has nothing to do with shadow catchers and ground planes.

The primary difference between Corona and vray mapping of hdri and dome lights is that Corona allows you to set a dimension to the radius of the dome and vray always assumes it's infinite. What I'm trying to create is a scene that uses a physically modelled dome and ground plane with a defined radius(like Corona). This allows me to adjust the radius to give a more pleasing projection of the background. That can be seen when comparing the first and second images attached in my original post. However I only want this to effect primary rays(background) and refraction. But as i pointed it this is not possible. All I want to know is am I missing something and is this even possible?

Using a vray projection on the background slot just brings me back to infinite dome and ground plane. Which is not what I am trying to achieve.

Does that make sense? Have you looked at the scene I attached?

Thanks

Matt

[hermit.crab]

Okay, I understand. First of all, we do have an improvement request (internal bug-tracker id: HOU-3012) for a similar to Corona dimension control for the VRayDome.
Second, the differences in reflection seem to be caused by the different HDRI projections of the 3d model and the VRayLight (there is a difference in how reflections are handled, which is based on the distance to their source - in your case, infinite and finite), so it's normal. It's actually observable if you scale the 3d model dome. You could multiply them in post if they are not satisfactory.

[matthew999]

Hi Hermit

Thats good to know that there already a feature request. thanks for your time on this. I have managed to make a hacky fix to get the functionality that i require.

cheers

Matt