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