Exchange Reflections in Glass Material

[LionHeart1985]

Hi!

I would need some urgent help.

I got an exterior scene, light is set up via a HDRI.

Now i would like to keep the lightning but change the reflections of the HDRI in photoshop in the windows to a specific image.

As there is also some geometry in the scene which is reflected in the windows, i would like to keep those reflections but change only the HDRI reflections.

Which settings have to be choosen for the glass material and the hdri to set this up via render elements for photoshop?

Thanks a lot for your help!!

[kenancakir]

You can use vray channels, it is "material id" channel i guess, after that use that channel to clear glass reflections..

[LionHeart1985]

kenancakir Hi! Thanks, i know that and i´m working with render passes for post prod. in phtotoshop. But i would like to keep the reflections of the mirrored object in the scene, but would like to exclude the HDRI in the reflections.

[kenancakir]

You can add white color to reflection slot in environment overrides, it will be easy to replace a solid color.. If you are using dome light, you should uncheck affect reflection option.. You can rerender the scene with solid color if you don't want to loose hdr reflections other than glass..

[konstantin_chaos]

Hi LionHeart1985,

The most robust solution would be to override the reflection environment in the scene with the image you want, avoiding the post-processing all together.
This can be done in the following way:

1. Disable the Affect Specular and Affect Reflection options in the Dome
2. Assign the other image to the Environment Override / Reflections slot

Trying to do the same in post would be quite hard.
You can try the following:

1. Set the Affect Channels option of all reflective materials to All Channels
2. Add a Cryptomatte or Material Random Color element
3. You should be then able to distinguish the environment from the scene objects in Photoshop

What kenancakir suggested is also an option but will lead to other complications.

I'd personally go for option 1.

Konstantin

[LionHeart1985]

Thank you all for your replys and tips!

I will give those different options a try to find the best method that fits in my workflow!

Cheers!

[DCHA34]

Hi LionHeart1985,

The most robust solution would be to override the reflection environment in the scene with the image you want, avoiding the post-processing all together.
This can be done in the following way:

1. Disable the Affect Specular and Affect Reflection options in the Dome
2. Assign the other image to the Environment Override / Reflections slot

This method works for me only in CPU mode. In GPU mode it does not work. Is this normal?

[konstantin_chaos]

Hi,

This method works for me only in CPU mode. In GPU mode it does not work. Is this normal?

It is not normal.
The described setup is fully supported on GPU in the latest version - V-Ray 5, update 1.5.

Here's an example:


Which V-Ray version are you using?
What is the result you see?

Konstantin

[DCHA34]

Hi Konstantin,

here is the packed project : https://ufile.io/h3j5knoh

and the results

[konstantin_chaos]

Hi,

Thanks for sharing the model.
There are actually a couple of issues that became apparent while testing your setup.
It seems that the Dome light affects objects differently depending on their material glossiness.
If you set the glossiness of all materials to 1 you'll have consistent results.

I'll log the other case in our internal bug tracking system and keep you posted on any progress we make.

Thank you for reporting this!

Konstantin