Re: Volume rendering of Irregular3DSet

• To: gunnar.sletta@xxxxxxxxxxx
• Subject: Re: Volume rendering of Irregular3DSet
• From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>
• Date: Mon, 19 Mar 2001 08:26:07 -0600

> I thought that there was some general getValue(x,y,z) function in Field,
> that allowed the renderer to render volume transparent of the actuall grid.
> This makes it of course a bit more complex.

There is such a method, evaluate(), but almost all Field
rendering techniques depend on the topology of the Field
sampling. For example, iso-surfaces (and iso-curves for
2-D Fields) depend on topology.

> Why are there 6 texture plane sets, and not only 3. It was my impression
> that the texture planes would look the same from both sides. Is it to
> bypass the depth sorting problem in Java 3D or something?

There need to be two for each axis (X, Y and Z) so the planes
can be correctly sorted whether you are looking toward the
positive or negative direction on the axis.

> Resampling works, but takes away much of the resolution since most of the
> elements are concetrated around one area. What about boundry extraction? Is
> the easiest way to simply locate all triangles on the boundry and put them
> in a Irregular2DSet?

You might try providing users with interactive control of
the bounds of the Linear3DSet, so they can zoom the resampling
in on a small area.

VisAD does not provide a method for computing boundaries, so
you'll have to write one. You'd put the boundary triangles in
an Irregular3DSet with manifold dimension = 2 rather than an
Irregular2DSet. Finding them could be tricky. Perhaps Curtis
has someting to add.

Cheers,
Bill
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html

• References:
  • Re: Volume rendering of Irregular3DSet
    • From: gunnar . sletta