How do I reduce overdraw in a forest scene with lots of foliage?

Question

Unity comes with an overdraw view that looks something like this:

We've probably all seen it, and have probably been advised to check for overdraw. How do you go about actually doing anything about it?

My specific case:

I'm currently seeing a lot of overdraw from my terrain grass and trees as they do not respect occlusion culling. This seems to be a limitation in Unity. Is there anything I could do about it to reduce overdraw without losing the lush environment?

For reference, here is the foilage responsible for most of the overdraw and I'm exploring options other than to simply reduce the amount of foliage in the scene and lose the aesthetics:

Answer 1

Overdraw is a complex subject and there is no one size fits all approach to solving overdraw problems, but reducing the number of overlapping objects that Unity cannot automatically sort is key. The best place to start investigating this issue is in Unity’s Scene view; there is a Draw Mode that allows us to see overdraw in our scene and, from there, identify where we can work to reduce it.

The most common culprits for excessive overdraw are:

1. transparent materials,

2. unoptimized particles

3. and overlapping UI elements

, so we should experiment with optimizing or reducing these. This article on the Unity Learn site focuses primarily on Unity UI, but also contains good general guidance on overdraw.

Ref: Optimizing graphics rendering in Unity games