Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: Stof on 2023-03-30, 02:58:21

Title: Render a light layer like a shadowcatcher layer but only light..?
Post by: Stof on 2023-03-30, 02:58:21

So I'm trying to render out a light layer as the headline says.
Currently, I have shadowcatcher with a transparent background like the one attached below, but I would need a light layer like that too it is very important only lighting from my scene is included primarily the environment light (HDRI)...

I hope someone knows how to do this, thanks in advance!

Title: Re: Render a light layer like a shadowcatcher layer but only light..?
Post by: maru on 2023-03-31, 13:23:47

Hi, can you please explain what exactly you mean by "light layer"?
What exactly are you trying to do, what is your end goal?

Title: Re: Render a light layer like a shadowcatcher layer but only light..?
Post by: Stof on 2023-04-01, 05:57:25

The above picture is only shadows in a render (shadowcatcher set for compositing), I want that but only for the light that hits a object...

A way you can get light layers is to do a render and then take the different light selects, put it into photoshop and set it for overlay (add). But the thing is that those renders do not have an alpha.

So the goal is to just get a render that only contains light or has an alpha that I can use inside photoshop.



Hope i explained this well enough :)

Title: Re: Render a light layer like a shadowcatcher layer but only light..?
Post by: romullus on 2023-04-01, 10:40:18

I'm not sure if i understood your task correctly, but you can setup lightmix and then render and save individual light layers. If you save to a format that supports alpha channel, then you can get alpha in every image that you save from VFB.

Title: Re: Render a light layer like a shadowcatcher layer but only light..?
Post by: Stof on 2023-04-11, 07:25:46

Okay so I have some examples here of how the light selects come out and that is as either .exr or .png
As far as I can see there's no transparency on the layers which is what I'm struggling with...
So essentially I'd just like that the black part of the renders comes out as transparent.

I have attached the files below...

PS.
I do understand that it can be composited within Photoshop by using the color dodge (add) blend mode although what I am trying to get is layers that already have transparency so there's no need for blending in photoshop...

Title: Re: Render a light layer like a shadowcatcher layer but only light..?
Post by: maru on 2023-04-11, 16:26:19

I am very sorry that we cannot really help you, but I still struggle with understanding what exact effect you are after. Could you please explain WHY you want to get this kind of layer? What is its usage? What are you doing and what do you want to achieve using this kind of layer?

Also, could you explain what exactly you mean by "light". Do you mean direct lighting that is cast onto all objects in your scene? Or maybe it should also include indirect lighting? Should it also include reflections, refraction?

What you may be interested in is the CShading_RawComponent render element set to "Diffuse". This is the raw lighting that hits all objects (direct + indirect) - https://docs.chaos.com/display/CRMAX/Render+Elements#RenderElements-CShading