Canada scene - Forest and impostors 🌲🌲🌲 (Patreon)

Or how to manage millions of trees without blowing up the computer 🖥️

The tree itself was made in SpeedTree, with custom made pine needles, and without any serious attempts at optimization weighs a hefty 2.4 million triangles!

For fun I did a quick test scene with a few hundreds of thousands of trees, and got a render time of about 17 minutes 😵 (6 times what I consider acceptable).

Making the trees geometry simpler would help, but it would still be overkill, so we need to do some magic by using impostors. 

They are mainly used in video-games, and based on the principle that a far away 3D object is indistinguishable from a flat, 2D picture of one.

All 64 angles of our impostor tree

So now our millions of triangles tree is a simple 2 triangles "billboard" that always face the camera. On top of that, the image displayed changes to match the sun's position so that it always appear to be lit correctly.

And now the same scene takes only 50 seconds to render!

I also implemented a rough version of the optimization I did on the fur, so that only the trees in view of the camera are loaded to save time and memory.

Looks like a lighthouse (but with trees)

Next step will be to add some diversity and make detailed models for the trees that will surround the cabin. Thankfully SpeedTree makes it really easy to do those things (especially now that I know how to use it 😁).