[vtkusers] Re: vtkFixedPointVolumeRayCastMapper question

Randall Hand randall.hand at gmail.com
Thu Jul 7 13:13:13 EDT 2005

I've done a little more investigating, and discovered a few more things:

The crash occurs when my app hits 46 degrees (I'm only doing even degrees 
right now), but still crashes at 48 and 50 degrees as well. When I reset it 
to start at 180, it crashed at 262 degrees with a similar error. In my 
application I'm rotating by adjusting the camera's Azimuth property.

The crash seems to be coming from the VTKKWRCHelper_SpaceLeapCheck() macro 
in vtkFixedPointVolumeRayCastHelper.h, which calls CheckMinMaxVolumeFlag in 
vtkFixedPointVolumeRayCastMapper.h. There seems to be some memory corruption 
going on that moves the actual error point in the core dump from one to the 
other, but they're related.

Has anyone else seen this problem before? I've filed it as bug #2029.

On 7/6/05, Randall Hand <randall.hand at gmail.com> wrote:
> I have a 128^3 volume that i'm trying to volume render. The images I get 
> are truly stunning, good job here guys.
> I've written a script to rotate the volume rendering from 0 to 180 
> degrees, in 2 degree increments. But every time I cross the 45degree mark on 
> any axis, it crashes with a segmentation fault.
> a Backtrace shows the following:
> [2:58:05pm]% dbx visualizer
> dbx version 7.3.4 (86441_Nov11 MR) Nov 11 2002 11:31:55
> where
> Core from signal SIGSEGV: Segmentation violation
> (dbx)
> Thread 0x10000
> > 0 vtkFixedPointVolumeRayCastMapper::CheckMinMaxVolumeFlag(unsigned 
> int*,int)(this = 0x14049428, mmpos = 0xfffffff9a50, c = 0) 
> ["/viz/home/rhand/src/ezViz/Utilities/VTK/VolumeRendering/vtkFixedPointVolumeRayCastMapper.h":529, 
> 0x5b12840]
> (dbx)
> This looks like a VTK bug to me. I've tried it with 15 different datasets 
> from the same project (same dimensions, etc), and all show the same 
> behavior.
> -- 
> Randall Hand
> Visualization Scientist
> ERDC-ITL Vicksburg, MS

Randall Hand
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