[vtkusers] depthbuffer issue?

[Flanery Jr, Raymond E.]

David,

I will check on that. I had not thought of that possibility, guess I can kick myself later. 

Ray Flanery
________________________________________
From: David E DeMarle [dave.demarle at kitware.com]
Sent: Tuesday, April 21, 2009 5:34 PM
To: Flanery Jr, Raymond E.
Cc: vtkusers at vtk.org
Subject: Re: [vtkusers] depthbuffer issue?

This reminds me of a precision issue. See bug 5753
(http://public.kitware.com/Bug/view.php?id=5753) and search markmail
for precision problem rendering
(http://paraview.markmail.org/search/?q=rendering+precision+problem)

OpenGL and thus VTK's rendering classes have a limited number of bits
to put dimensions in while rendering.

When the data dimensions push those limits (for example a polygonal
sphere of size 10e-6 located 10e+6 units away from the origin) we've
noticed effects like those you describe. As yet don't have a general
purpose solution, and the answer so far is fixup the data.

David E DeMarle
Kitware, Inc.
R&D Engineer
28 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-371-3971 x109



On Tue, Apr 21, 2009 at 5:17 PM, Flanery Jr, Raymond E.
<flaneryrejr at ornl.gov> wrote:
> I have a set of bldg footprints for nashville that I have cut down to about 850 bldgs. I am trying to extruding  them in vtk and am having the problem that as I move around in the data set triangles are being constantly drawn improperly, almost like the normals are flopping around. If I extract a smaller set of the buildings, say 5-20 everything looks normal, same code. Any suggestions for what I am seeing?
>
> Ray Flanery
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