Sorting transparent polygons is a very hard problem,
especially for complex and unpredictable shapes like
iso-surfaces. And note the sort order must change as
the user interactively rotates in 3-D. In Vis5D we
got around this problem by using screen-door
transparency, but the last time (a long time ago) I
tried it in Java3D it didn't work right.
I think transparency is over-rated. 3-D images are
ambiguous enough and using transparency just adds to
that ambiguity.
Cheers,
Bill
On Wed, 20 Apr 2005, JR Schmidt wrote:
> I have encountered a problem with VisAD and isosurface transparency. From
> browsing the archives of the list, it seems that there may be a problem with
> transparency in general, due to a lack of a z-sort in Java3D. I am not sure
> whether this issue has been resolved in Java3D 1.3.
>
> Transparency seems to work, for the most part, except that I get 'banding'
> in the resulting image. The banding changes as I rotate the image. For
> example, see
> http://www.webmo.net/test/moviewer.jpg
>
> Are such problems to be expected, due to deficiencies in Java3D? Or are
> there possible workarounds? I have tried changing the transparency mode in
> the GraphicsControl, which does not seem to help (or hurt).
>
> JR Schmidt
> UW-Madison
>
>
