Re: texture mapping and volume rendering

• To: visad-list@xxxxxxxxxxxxx
• Subject: Re: texture mapping and volume rendering
• From: "From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>" <billh@xxxxxxxxxxxxx>
• Date: Tue, 1 Jun 1999 18:43:52 -0500 (CDT)

Hi Doug,
 
> 1) How can I display an image (e.g. satellite photo (e.g. gif)) on a
> curved surface (e.g. surface terrain)?
 
The easiest way is to use the static method FieldImpl.combine() to
comine the image and the terrain into a single FlatField (put the
image first in the Field[] array passed to combine so that the
terrain will be resampled to the domain Set of the image).  You can
use the GraphicsModeControl.setCurvedSize(int curved_size) method
to determine the number of image pixels across a "flat" region of 
the terrain (the default is 10).  Obviously, map the image component
of the combined FlatField to color, and map the terrain component
to ZAxis.
 
Another approach is to use the TextureRendererJ3D class written by
Lutz Laemmer (he wrote it in about April 98 and it is possible that
some DataRenderer signatures have changed since then).  This class
illustrates that a DataRenderer may combine more than one Data object
in a single depiction, and (I think) does what you want.  There is a
link to it from the VisAD web page.
 
> 2) Any idea why Test61 gives me a cube of solid gray layers on my NT box
> but produces the lovely (and expected, I assume) semi-transparent
> colorful shape on my Linux box? I read something in the archive about a
> change in Java3D so I downloaded the latest Java3D (1.1.1) from
> java.sun.com. It didn't help.
 
Sorry, we noticed this too.  Our volume rendering uses 3-D textures
which seem to not work on NT.  In fact, we would be very interested
to hear if it worked correctly on anyone's NT box.  Curtis tried it
with both the NT and 95 OpenGL and it failed with both.  I'll check
this out with the Java3D folks.  If this turns out to be a real
problem, we may have to eliminate 3-D textures from our volume
rendering algorithm.
 
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