Can I have 500,000+ trees?

My game lets the user run a simulation of environment over many years. The problem is that the environmental model will sometimes generate a year will 500,000+ trees, sometimes almost 1,000,000! While you can still click on the trees, I am not using colliders (which would cap me at ~65,000). When I try and render a environmental model, I am getting the following error: “Fatal Error - Out of Memory”. It works during years with <~500,000 trees.

My guess is that Unity is just unhappy with the amount of rendering that is being requested. Is this correct? Also, are trees being rendered even if they are not in the camera’s line of site (hidden by terrain or behind camera). Is there someway to further optimize the billboarding of trees in the far distance? I was thinking maybe there is some way to dynamically apply a different texture to the most distant terrain instead of drawing the trees? I would like to preserve the visual effect I have in the below picture (that is about 200,000 trees in terrian).

do occlusion culling.

Yes, 500,000 trees is too many.

Can you actually visit those far-away areas? Or do you just like the effect of having that many trees, without the need to actually go there?

If you don’t need to go there, then there are many possible ways to cheat it. If you do need to go there… well, it still can be cheated, but you have to be more creative about it.

You can do it with lod level of detail
You can have 3 kind of same tree low medium and high res
The closer to the cam they switch by themselves
Also with occlusion culling
Also have just planes with picture of tree billboard technique
Just some suggestions