Make grey background while using HDRI for renders

Question

I just want to ask if anyone knows how to make background grey while using HDRI so it would be the same as in Substanse painter "Environment Opacity slider" or basically the same as in Material Preview Mode in Blender?

Is it possible to make it without options that listed below?:

Not a transparent background and then add grey background picture in photoshop;
Not a heavily blurred background (I found this option here but it still has colors);
Without adding a grey plane at the back while rendering

Just pure grey

https://blender.stackexchange.com/questions/178080/can-i-use-an-hdri-for-reflections-only-and-not-have-its-light-affect-the-scene — Nascent Space, Apr 20 '21 at 02:23
Does this answer your question? Can I use an HDRI for reflections only, and not have its light affect the scene? — Nascent Space, Apr 20 '21 at 02:24
Thank you for the answer but I just did a quick test and it looks great but not exactly what I'm looking for :(
It adds some white background but image with this setups looks different than with just HDRI
Don't know how to submit picture in comments but it look like this: https://i.ibb.co/wNHyrJL/Test.png
1- with just HDRI
2 - same HDRI but with light rays added — Irina L, Apr 20 '21 at 04:46
So you want Hdri lighting and reflections but leaving the background as completely grey? — Nascent Space, Apr 20 '21 at 04:56

score 2 · Answer 1 · answered Apr 20 '21 at 06:05

The best way is to use film->transparent. Now go into compositing section and click on use node.

Add an alpha over node before output node and chose your desired color. This way,the render will use the HDRI and then make background as chosen in the apha over node. Also,if your entire render comes as single color,try switching the color inputs of alpha over node

Christopher Bennett · Answer 2 · 2021-04-20T05:41:49.623

1

Connect it by using 2 Background shader nodes - one connected to the image texture, and the other with just your grey color - and then connect them with a Mix Shader using the Is Camera Ray output of a Light Path node as a mix factor.

edited Apr 20 '21 at 05:41

answered Apr 20 '21 at 05:15

Christopher Bennett

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Thanks a million!! That's what I was looking for – Irina L Apr 20 '21 at 05:25

Make grey background while using HDRI for renders

2 Answers2