[vtkusers] vtk question

[Joyoni Dey]

Hello,

I had the following problem and fixed it  but was wondering if someone can 
illuminate why exactly it worked.

I have a 512x512x400 volume. I am rotating a camera about the center of a 
cube in a circle from about
-90deg to +90deg. The circle is perpendicular to the z-axis. The volume 
instead of getting rotated smoothly jittered (staggered) quite a bit --
and the jittering was more pronounced at two angles where the volume 
diagonal was facing camera -- that is the extent of the
volume was the most. I thought something is up with the frustrum boundary 
cutting off the volume and decided to look into the
clipping plane range.

It turns out  increasing the *near* range of the clipping -- reduces the 
jitter. Increasing from 0.01 to 0.03 (or more) gets rid of the
jittering altogether. While I am glad it worked, I strictly do not 
understand why. And why exactly was the "diagonal" directions
more jittery.

Any thoughts, thanks,
Joyoni