I am a learner in Houdini. I have a few basic questions about rendering.
There are a 3 kinds of auto-generate DepthMap shadow. (mid-point Z, closest Z, farthest Z) What are their differences? (the help document does not state those very clearly.)

Also, in RIB shadow style, there is one shadow style called, “min/max shadows”. What is min/max shadow?

In shop, there are a series of Light shaders called “Ator *”. What is Ator *?

Thank you for your attention!

wasn't Ator Pixar's Alias to Renderman?

They are pretty much what they say - I think there is something in the help about them.

Closest Z saves the distance to the nearest surface to the light.
Furthest Z saves the distance to the furtherest surface of the closest object ( I think)
Mid point Z saves the average of the two.

And this from the help

The style of depth map to generate from this light source. Mid-Point z-depth shadows help to eliminate self shadowing artifacts, but do not accurately represent the distance to the occluding object and so should not be used for atmospheric lights. Currently only RIB generation supports deep shadow map generation.