[vtkusers] seams between transparent surfaces

[Cory Quammen]

Paul,

When drawing transparent geometry, geometry needs to be sorted in
depth order, or you need to use depth peeling which in a sense does
the depth sorting for you. Fortunately, VTK implements depth peeling.
In your vtkRenderer, call UseDepthPeelingOn(). This ought to eliminate
the seams, assuming your graphics hardware supports VTK's
implementation of depth peeling.

Cory

On Fri, Dec 5, 2008 at 2:11 PM, Paul Hamill <paulh at txcorp.com> wrote:
> Hi -
>
> We're using VTK called from Python to create climate data visualizations. A
> structured mesh is divided into sub-meshes or "tiles" to support
> parallelization. We are seeing "seams" between meshes when they have alpha
> transparency. The attached screenshot is a simplified example of this. There
> are two adjacent pairs of planar surfaces. When viewed from some angles a
> polygonal shape appears where the surfaces meet. (Here it looks like a wide
> line running across the middle of the front plane.) The Python code that
> generates this image is also attached. Run "python exSeamProblem.py" to
> create this image and rotate it to see the seam.
>
> Any advice or information about this problem is much appreciated.
>
> Thanks -
> Paul
> --
>   Paul Hamill
>   Tech-X Corp
>
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-- 
Cory Quammen
Center for Computer Integrated Systems for Microscopy and Manipulation (CISMM)
Department of Computer Science
University of North Carolina at Chapel Hill
http://www.cs.unc.edu/~cquammen