How do I render a decent swimming pool animation in a reasonable amount of time?

Question

I making an animation that features a swimming pool. The animation is going to be ~2 minutes, and I would like the swimming pool to splash when the characters jump in it, and ripple when they move. I want the water to be transparent but also reflective, and I also want there to be a pattern at the bottom of the pool from the caustics. I also want the animation to render fast (1-2 minutes rendering time per frame, the rest of the scene is mostly diffuse materials and low poly geometry, HD if possible or at least 720p) on the CPU in cycles. How do I do this? Is there anyway to composite or bake textures of the scene so that the scene will render at a decent speed?

I also want to know whether or not the fluid simulation is the best way to do this. Is there a way to use particles, an ocean modifier or dynamic paint to get a faster bake?

Answer 1

The most expensive part of this rendering is going to be the caustics. If you want real caustics, they will probably be grainy. In cycles you can spend as time as you want on each frame, but less time will make a more grainy render.

If you want to fake caustics, there are a number of options. They give different results and different rendering speeds.

• Add an emitting shader to the pool floor. Make it emit light in a caustic-like pattern. You can probably animate like this: How to animate noise texture "seed"?
• Use vector math to fake caustics. Explained here http://urchn.org/post/fake-caustics-in-cycles
• You can bake a texture in cycles from the first frame caustics. Use that for the rest of the frames. This will give a physically correct first frame but will not animate.

I think that the vector-math approach will give you best results.