GI Environment Confusion

[henryeastman]

Please work through my (perhaps twisted) logic and tell me where I'm going wrong.

 

Using an HDRI in a dome light is the preferred workflow. This HDRI should be low-res and blurred to help render times and produce nice soft shadows.

 

A high-res, non-blurred version of the HDRI can be used as an environment background and for reflections. In which case you should put it in Max's standard 'Environment Map' slot. However won't this also affect the lighting and mess with your dome light HDRI?

 

If you didn't want the background to affect the lighting you would use V-Ray's environment overrides, by putting in your blurred HDRI into the GI environment slot. But now your using the non-preferred workflow of setting up an HDRI. Also when would you want to override reflection and refraction?

 

If using a V-Ray sun should you use an HDRI and V-Ray sky map (which helps the V-Ray sun) in tandem?

 

So basically it would mean the world to me if someone could be by night in shining armour and clear up all this confusion for me!

 

Thank you!

[Francisco Penaloza]

I got a little confused reading your post, so here is what I know

Basic lighting, Vray Sun/Sky with this VRay by default will put the Vray sky shader on the environment to display the sky.

 

Only using an HDRI in the Max environment slot also will give you lighting and reflections, but this make V Ray work a little hard than using a VRay dome light.

 

VRay dome light with an HDRI will work just fine. (better quality of HDRI better shadows less color tint) if you want to replace the background(sky) in post you can hide the light (in the light properties) or you can check affect Alpha, this will render your HDRI as sky but you'll get an alpha to cut it out later.

 

For any reason, you need more flexibility, then you can use the VRay overwrites.

GI: it is only used to overwrite any environment lighting, such Max environment, this won't be visible on speculars or reflections.

Reflection/refraction environment, if you put any image here, this is what will be reflected as Sky, unless of course your object is covered by other geometry.

 

Using a blurry version of your HDRI for lighting, it only help to reduce render time and high specular brightness. since this image is blurred the Antialising won't work that hard, then over all render will be faster.

 

Soft shadows may be affected by this blurred image but if your HDRI has low light information this will make your shadows softer too.

 

if you want to use VRay sun, you can use a dome light with the HDRI together. Depending of the quality of your HDRI you need to align your sun to the position of the sun in the image, otherwise you'll get double shadows.

[henryeastman]

Thanks for your helpful reply.

 

So what you're saying is the V-Ray sky in Max's environment map slot does not contribute any lighting or reflections, it's only a background. But an HDRI in the same slot will contribute to lighting and reflections?

[Francisco Penaloza]

Thanks for your helpful reply.

 

So what you're saying is the V-Ray sky in Max's environment map slot does not contribute any lighting or reflections, it's only a background. But an HDRI in the same slot will contribute to lighting and reflections?

 

NO, what I meant is using VRay sun/Sky it the most basic setup it work just fine, by default VRay will put the VRay Sky shader in the Max environment so you can see it and also be used as environment lighting.

If you use any of the VRay's overwrites (GI or Reflections-refractions) those will skip max environment.