[vtkusers] Strange rendering with 2-voxel thick volume
Aashish Chaudhary
aashish.chaudhary at kitware.com
Wed Oct 4 12:12:07 EDT 2017
Got it, thanks!
On Wed, Oct 4, 2017 at 12:07 PM Elvis Stansvik <elvis.stansvik at orexplore.com>
wrote:
> 2017-10-04 17:43 GMT+02:00 Aashish Chaudhary <
> aashish.chaudhary at kitware.com>:
> > thanks..I just wanted to make sure that we remove that as one of the
> > culprit. I am wondering if it is something to do with the geometry
> (bbox) or
> > something to do with some edge case (calculation that is going off
> because
> > of very small delta). Although in the past we have tried very think
> volumes
> >
> > Is it possible for you to send a sample dataset to us?
>
> My test case includes the data used. It's simply a 200x200x2 volume
> filled with all data points set to 0.01.
>
> Elvis
>
> >
> > On Wed, Oct 4, 2017 at 10:09 AM Elvis Stansvik
> > <elvis.stansvik at orexplore.com> wrote:
> >>
> >> Hi Aashish,
> >>
> >> 2017-10-04 15:47 GMT+02:00 Aashish Chaudhary
> >> <aashish.chaudhary at kitware.com>:
> >> > Please make sure that your sampling distance is less than < 2. You can
> >> > set
> >> > the sampling distance manually in the API.
> >>
> >> Hm. I don't think it's related to sampling distance. In the test case
> >> I'm not setting sampling distance at all, so I think it should default
> >> to 1, and then be automatically adjusted during interaction.
> >>
> >> In any case, even if I amend the test case with e.g.:
> >>
> >> volumeMapper->AutoAdjustSampleDistancesOff();
> >> volumeMapper->SetSampleDistance(0.2);
> >> ...
> >> volumeMapper2->AutoAdjustSampleDistancesOff();
> >> volumeMapper2->SetSampleDistance(0.2);
> >>
> >> The result is the same.
> >>
> >> Elvis
> >>
> >> >
> >> > On Wed, Oct 4, 2017 at 8:23 AM Elvis Stansvik
> >> > <elvis.stansvik at orexplore.com>
> >> > wrote:
> >> >>
> >> >> Hi all,
> >> >>
> >> >> In the test case below, I render one 200x200x2 volume and one
> >> >> 200x200x3 volume, both with the same settings.
> >> >>
> >> >> The 200x200x3 volume looks as expected (the light gray one in the
> >> >> attached screenshot), while the 200x200x2 one looks strange (too
> dark,
> >> >> and with some kind of gradient artifact).
> >> >>
> >> >> Is there some limitation on rendering a volume that is only 2 thick
> in
> >> >> one of the dimensions? I can understand why a volume of thickness 1
> >> >> can't be rendered properly, since VTK must have values to interpolate
> >> >> between, but 2 should be OK right?
> >> >>
> >> >> Thanks for any help.
> >> >>
> >> >> Elvis
> >> >>
> >> >>
> >> >> main.cpp:
> >> >>
> >> >> #include <algorithm>
> >> >>
> >> >> #include <vtkColorTransferFunction.h>
> >> >> #include <vtkGenericOpenGLRenderWindow.h>
> >> >> #include <vtkGPUVolumeRayCastMapper.h>
> >> >> #include <vtkImageData.h>
> >> >> #include <vtkNew.h>
> >> >> #include <vtkPiecewiseFunction.h>
> >> >> #include <vtkProperty.h>
> >> >> #include <vtkRenderer.h>
> >> >> #include <vtkRenderWindow.h>
> >> >> #include <vtkRenderWindowInteractor.h>
> >> >> #include <vtkVolume.h>
> >> >> #include <vtkVolumeProperty.h>
> >> >>
> >> >> int main(int argc, char *argv[])
> >> >> {
> >> >> vtkNew<vtkColorTransferFunction> colorFunction;
> >> >> colorFunction->AddRGBPoint(0.0, 0.0, 0.0, 0.0);
> >> >> colorFunction->AddRGBPoint(1.0, 0.0, 0.0, 0.0);
> >> >>
> >> >> vtkNew<vtkPiecewiseFunction> opacityFunction;
> >> >> opacityFunction->AddPoint(0.0, 0.0);
> >> >> opacityFunction->AddPoint(1.0, 1.0);
> >> >>
> >> >> // A 200x200x2 volume
> >> >> vtkNew<vtkImageData> imageData;
> >> >> imageData->SetExtent(0, 199, 0, 199, 0, 1);
> >> >> imageData->AllocateScalars(VTK_FLOAT, 1);
> >> >> std::fill_n(static_cast<float *>(imageData->GetScalarPointer()),
> >> >> 200 * 200 * 2, 0.01);
> >> >>
> >> >> vtkNew<vtkGPUVolumeRayCastMapper> volumeMapper;
> >> >> volumeMapper->SetInputData(imageData.Get());
> >> >>
> >> >> vtkNew<vtkVolumeProperty> volumeProperty;
> >> >> volumeProperty->SetScalarOpacity(opacityFunction.Get());
> >> >> volumeProperty->SetColor(colorFunction.Get());
> >> >> volumeProperty->ShadeOff();
> >> >>
> >> >> vtkNew<vtkVolume> volume;
> >> >> volume->SetMapper(volumeMapper.Get());
> >> >> volume->SetProperty(volumeProperty.Get());
> >> >> volume->SetPosition(120, 0, 0);
> >> >>
> >> >> // A 200x200x3 volume
> >> >> vtkNew<vtkImageData> imageData2;
> >> >> imageData2->SetExtent(0, 199, 0, 199, 0, 2);
> >> >> imageData2->AllocateScalars(VTK_FLOAT, 1);
> >> >> std::fill_n(static_cast<float *>(imageData2->GetScalarPointer()),
> >> >> 200 * 200 * 3, 0.01);
> >> >>
> >> >> vtkNew<vtkGPUVolumeRayCastMapper> volumeMapper2;
> >> >> volumeMapper2->SetInputData(imageData2.Get());
> >> >>
> >> >> vtkNew<vtkVolumeProperty> volumeProperty2;
> >> >> volumeProperty2->SetScalarOpacity(opacityFunction.Get());
> >> >> volumeProperty2->SetColor(colorFunction.Get());
> >> >> volumeProperty2->ShadeOff();
> >> >>
> >> >> vtkNew<vtkVolume> volume2;
> >> >> volume2->SetMapper(volumeMapper2.Get());
> >> >> volume2->SetProperty(volumeProperty2.Get());
> >> >> volume2->SetPosition(-120, 0, 0);
> >> >>
> >> >> vtkNew<vtkRenderer> renderer;
> >> >> renderer->AddVolume(volume.Get());
> >> >> renderer->AddVolume(volume2.Get());
> >> >> renderer->SetBackground(1.0, 1.0, 1.0);
> >> >>
> >> >> // Render with "plain" render window / interactor
> >> >> vtkNew<vtkRenderWindow> window;
> >> >> window->SetMultiSamples(0);
> >> >> window->AddRenderer(renderer.Get());
> >> >>
> >> >> vtkNew<vtkRenderWindowInteractor> interactor;
> >> >> interactor->SetRenderWindow(window.Get());
> >> >> interactor->Start();
> >> >>
> >> >> return 0;
> >> >> }
> >> >>
> >> >>
> >> >> CMakeLists.txt:
> >> >>
> >> >> cmake_minimum_required(VERSION 3.1)
> >> >>
> >> >> project(TestCase)
> >> >>
> >> >> find_package(VTK 8.0 COMPONENTS
> >> >> vtkCommonCore
> >> >> vtkCommonDataModel
> >> >> vtkCommonExecutionModel
> >> >> vtkCommonMath
> >> >> vtkFiltersSources
> >> >> vtkGUISupportQt
> >> >> vtkInteractionStyle
> >> >> vtkRenderingCore
> >> >> vtkRenderingOpenGL2
> >> >> vtkRenderingVolume
> >> >> vtkRenderingVolumeOpenGL2
> >> >> REQUIRED
> >> >> )
> >> >>
> >> >> add_executable(TestCase main.cpp)
> >> >>
> >> >> target_link_libraries(TestCase PUBLIC
> >> >> vtkCommonCore
> >> >> vtkCommonDataModel
> >> >> vtkCommonExecutionModel
> >> >> vtkCommonMath
> >> >> vtkFiltersSources
> >> >> vtkInteractionStyle
> >> >> vtkRenderingCore
> >> >> vtkRenderingOpenGL2
> >> >> vtkRenderingVolume
> >> >> vtkRenderingVolumeOpenGL2
> >> >> )
> >> >>
> >> >> target_include_directories(TestCase PUBLIC
> >> >> ${VTK_INCLUDE_DIRS}
> >> >> )
> >> >>
> >> >> target_compile_definitions(TestCase PUBLIC
> >> >> ${VTK_DEFINITIONS}
> >> >> )
> >> >>
> >> >> set_target_properties(TestCase PROPERTIES
> >> >> CXX_STANDARD 14
> >> >> CXX_STANDARD_REQUIRED ON
> >> >> )
> >> >> _______________________________________________
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> >> >>
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> >> >>
> >> >> Please keep messages on-topic and check the VTK FAQ at:
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> >> >>
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>
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