[vtkusers] The View coordinate system: meaning of the z value

[David Cole]

The documentation here:

    http://www.vtk.org/doc/nightly/html/classvtkCoordinate.html#details

says:

    "VIEW - x-y-z (-1,1) values in camera coordinates. (z is depth)"

I understand how to call WorldToView and ViewToWorld on a renderer to
go back and forth between these coordinate systems, but I'm trying to
understand what the math is for the z-value.

What I think I'm seeing is the z value goes from 0 to 1 from the near
clipping plane to the far clipping plane, but it does not appear to be
exactly linear. It's nearly linear within the 0 to 1 range, but from
-1 to 0, the view coordinates are much closer together in world space
than they are from 0 to 1, and from 1 to 2, they are much farther
apart in world space than the 0 to 1 range.

What is the exact mathematical meaning of the z-value of the view
coordinate system as it relates to distance in world coordinates?

Are there any good articles or examples anybody can point to as a good
tutorial on using View coordinates?

My goal is to reflect and project some physically measured artifacts
from the real world (in front of the screen), and have the reflection
"look good". So I want to express the points involved in View
coordinates, and then reflect /"adjust z" and then call ViewToWorld to
get the right VTK world coords for these things...


Thanks,
David C.


P.S. -- please forgive the previously prematurely sent nearly empty
email... Definitely a PBKAC.