Images as planes gives black boxes with many instances

Question

I'm trying to make a forest with Images as Planes, which gives some weird black boxes in the render. I have created a Hair Particle System with 5000 particles. In the Render Settings I have set Light Paths / Transparent to 256. Still the black boxes appear and I don't know how to get rid of them. What do I have to do differently? Thanks for your help.

Blender File

Answer 1

I would say your issue is Z-fighting ... overlapping faces (faces share the same location).

You can see glittering already in Solid View mode. Blacks appears also in front planes.

Try to lower number of particles ... If you can't avoid overlapping from location - try Randomize Rotation, just a bit so the planes are crossing, but doesn't lay on each other.

Specularity set to zero.