[vtk-developers] Volume rendering very large StructuredGrids

[Jim Geach]

just to report that i have tested the fix for the 32-bit overflow bugs in the fixed point volume mapper, etc. implemented in VTK 6.

i rendered a 1536^3 volume with the expected results, and none of the weird artifacts that were present before.

many thanks, jim

On 2012-04-10, at 11:13 PM, David Gobbi wrote:

> Yes, both the mapper and the space-leaper filter had 32-bit overflow bugs.
> These bugs were reported a couple months ago, and the fix was merged
> a few days ago, just before the VTK tree was modularized.
> 
> To update your tree to the merge commit, which will bring in all the
> VTK 6 pipeline changes but none of the modularization changes, do
> the following:
> 
> git fetch origin master
> git merge fc4c570a
> 
> To avoid all the VTK 6 pipeline changes, you can try cherry-picking
> the fix (it's commit a3feef0d) but no guarantees.
> 
> If you get a chance to test the fix, please report your findings.  The
> more testing that this code gets, the better.
> 
> - David
> 
> 
> On Tue, Apr 10, 2012 at 8:03 PM, Jim Geach <jimgeach at physics.mcgill.ca> wrote:
>> 
>> Dear developers,
>> 
>> I am using vtkFixedPointVolumeRayCastMapper to render very large (1536^3) volumes with two data components. So far, I have been unsuccessful in properly rendering volumes when the number of elements >MAX_INT. I'm using v5.11.0.
>> 
>> Independent checks (e.g. simple 2D projections of the data) show that the problem is not with the data, but in the rendering itself.
>> 
>> I have built VTK with USE_64BIT indexing ON, and the volume rending actually completes and dumps an image without complaint. However, but the image is garbled: it looks broadly correct, but some chunks are missing, there are large discontinuities, etc.
>> 
>> Is this a bug? e.g. is there some int casting within a function of vtkFixedPointVolumeRayCastMapper (space leaping?) or associated volume rendering code that prevents VTK from properly volume rendering of 64-bit class data arrays?
>> 
>> Any help on this issue would be very gratefully received!
>> 
>> Thanks, Jim

---
Dr James Geach
McGill University

Ernest Rutherford Building,
3600 Rue University, Montreal, QC

jimgeach at physics.mcgill.ca
514-398-1449
http://www.physics.mcgill.ca/~jimgeach