Using Indirect Multipliers
Sometimes your scene might have really dark shadows with little to no detail, but you want those details to show through. A good way to control and enhance this subtle light is by using Indirect Multipliers.
The Unity documentation provides some insightful information regarding what exactly the Indirect Multiplier does. The value adjusts the intensity of indirect light, meaning bounced light and global illumination. As stated, a value lower than 1 will dim the light with each bounce, while a value greater than 1 will brighten the light with each bounce. So basically, increasing the value of the indirect multiplier is a great way to lighten dark shadows to increase the visible detail.
For example I have a directional sun light using a Mixed mode, meaning it will make two lighting passes, one for baked and one for real-time light.
It’s a night time scene with the sun at a very low value of 2, which will make things generally pretty dark…especially the shadows. By default, the indirect multiplier is set to a value of 1.
Here is what the scene looks like. The trees are practically silhouettes and covered in shadow.
Since the indirect multiplier can be used to boost up indirect light, I add some light probes to the scene to help bounce the baked lighting into to the other objects.
Here is the light probe group after duplicating it around the scene.
I also need a static object for the light probes to gather ambient lighting information from, so I select all of the cobblestone floor and give it the static tag in the inspector. Now the mixed directional light performs some light baking on to the static floor, which will bounce light off of it and back into the environment. Light probes help this baked lighting information move through the scene.
Now let’s crank up the indirect multiplier to 500. The value really only has to go this high because this is a night scene, so there isn’t a whole lot of light to begin with. A brighter day time scene would most likely require a lower value.
The scene remains a dark evening scene, but now you can see the textures appear much more in the shadow of the trees. The flowers are also nor more visible being so close too the ground where the bounced lighting is coming from. This is a bit too much on the indirect multiplier for my taste, but I wanted to make sure the changes were visible enough for demonstration.
Thanks for reading and have fun bringing those details out of the shadows!