[vtkusers] Memory issues with vtkOpenGLGPUVolumeRayCastMapper and DirectX

[Eric Foo]

Hi all, 

Having some trouble compiling a GPU volume render code using vtkOpenGLGPUVolumeRayCastMapper. I know the code works because it was modified from a working version using vtkFixedPointVolumeRayCastMapper. The dataset size is in unsigned short, 512 x 512 x 300 voxels and I am running on a Windows 7 with a Quadro FX 4800 with 1.5GB of video memory. Initially I was getting poor frame rates, about 1-2 fps.

I did find this post http://vtk.1045678.n5.nabble.com/dashboard-maintainers-To-make-TestGPUInfo-works-properly-td1254242.html. The post says to build VTK with DirectX, which I have done. I installed the latest DirectX SDK (June 2010), and pointed CMake to this directory before building VTK 5.6.1. 

To compile and build the code, I linked the Visual Studio project to the installed directory and including d3d9.lib, dxgi.lib, ole32.lib. The code built fine but upon loading the dataset, the app is throwing an error for vtkOpenGLGPUVolumeRayCastMapper.cxx at line 5810 "No memory left on the GPU even for a minimal block."  And in theory, the graphics card should have enough memory to cover this dataset. When loading a smaller dataset (512 x 512 x 100), the app does not throw the line 5810 error but nothing gets rendered.

Any help or ideas would be appreciated. Thanks!

eric
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