Atomic Perception

The comper could use After Effects 3D tools to extract the depth pass, and write it out as a PNG sequence. Not sure what the point is, however. That would be downgrading your depth value from 16 bit to 8 bit, losing precision in the process.

One thing to try, is to assign a default material. Then make sure the viewport Material button is turned on (it is by default), and activate the lighting with shadows button. You may want to add an area light or environment light as well.

Try using a particle system instead, then you can add the box as a collision object the points will avoid. There are a bunch of tutorials on shape changing points, look one up.