When should I use a kd-tree? [closed]

Question

The other day, I was reading about kd-trees. I was looking for a concrete and simple situation where such a data structure could be useful. Does anybody have such an example?

Answer 1

I used a kd-tree to simulate light transport through spray generated by a wave. This made it possible to render droplets of spray that weren't just illuminated by lamps, but also indirect lighting coming from other droplets.

I stored points of spray in a kd-tree and then used the kd-tree to quickly find which points were near each other, and hence which droplets of water were illuminated by each other. (Actually, it was a little more sophisticated, but the structure was still a kd-tree.) This made it possible to render a nice glow through the spray.

Here's a picture of the method in use.

Note how the spray around the lights is glowing with scattered light.