[vtk-developers] Volume rendering very large StructuredGrids

[David Gobbi]

Thanks for the confirmation, Jim.  I've marked the bug as closed.

I still recommend that you add a note for the multithreading bug in
the fixed point mapper, your comments will be useful to whoever
eventually fixes it:
http://www.vtk.org/Bug/view.php?id=12115

 - David


On Mon, Apr 16, 2012 at 3:18 PM, Jim Geach <jimgeach at physics.mcgill.ca> wrote:
>
> 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
>
>
>