vtkCamera::SetModelTransformMatrix, SetUserViewTransform or SetUserTransform produce incorrect volume rendering
Hi,
Using vtkCamera::SetModelTransformMatrix or SetUserViewTransform or SetUserTransform does not render the volume correctly - the result appears inappropriately sheared. I have sample code based on SmartVolumeMapper example with a simple translation applied to vtkVolume, and a modelview transform I want to apply to vtkCamera. I've attached screenshots of the issues - first is the default rendering, second image is renering after using interactor to reset view and rotate with mouse.
The issue is with 8.0.1, OpenGL2 rendering backend.
I was discussing same issue against 6.3 a while ago on the user mailing lists: http://markmail.org/message/xy7r5dtyzrfmaxrl
#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkSphere.h>
#include <vtkSampleFunction.h>
#include <vtkSmartVolumeMapper.h>
#include <vtkColorTransferFunction.h>
#include <vtkPiecewiseFunction.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkVolumeProperty.h>
#include <vtkCamera.h>
#include <vtkImageShiftScale.h>
#include <vtkImageData.h>
#include <vtkPointData.h>
#include <vtkDataArray.h>
#include <vtkTransform.h>
static void CreateImageData(vtkImageData* im);
int main(int argc, char *argv[])
{
vtkSmartPointer<vtkImageData> imageData =
vtkSmartPointer<vtkImageData>::New();
CreateImageData(imageData);
vtkSmartPointer<vtkRenderWindow> renWin =
vtkSmartPointer<vtkRenderWindow>::New();
vtkSmartPointer<vtkRenderer> ren1 =
vtkSmartPointer<vtkRenderer>::New();
ren1->SetBackground(0.1, 0.4, 0.2);
/*
Setup camera
*/
vtkSmartPointer<vtkTransform> volumeUserTransform = vtkSmartPointer<vtkTransform>::New();
volumeUserTransform->Translate(2, 2, 0);
vtkSmartPointer<vtkTransform> cameraModelviewTransform = vtkSmartPointer<vtkTransform>::New();
cameraModelviewTransform->Translate(-2, -2, -10);
vtkSmartPointer<vtkCamera> camera = vtkSmartPointer<vtkCamera>::New();
camera->SetModelTransformMatrix(cameraModelviewTransform->GetMatrix());
//camera->SetUserViewTransform(cameraModelviewTransform); //<-- Broken but differently broken rendering from SetModelTransformMatrix
//camera->SetUserTransform(cameraModelviewTransform); //<-- Nothing rendered at all
ren1->SetActiveCamera(camera);
renWin->AddRenderer(ren1);
renWin->SetSize(512, 512);
vtkSmartPointer<vtkRenderWindowInteractor> iren =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
iren->SetRenderWindow(renWin);
renWin->Render(); // make sure we have an OpenGL context.
vtkSmartPointer<vtkSmartVolumeMapper> volumeMapper =
vtkSmartPointer<vtkSmartVolumeMapper>::New();
volumeMapper->SetBlendModeToComposite(); // composite first
volumeMapper->SetInputData(imageData);
vtkSmartPointer<vtkVolumeProperty> volumeProperty =
vtkSmartPointer<vtkVolumeProperty>::New();
volumeProperty->ShadeOff();
volumeProperty->SetInterpolationType(VTK_LINEAR_INTERPOLATION);
vtkSmartPointer<vtkPiecewiseFunction> compositeOpacity =
vtkSmartPointer<vtkPiecewiseFunction>::New();
compositeOpacity->AddPoint(0.0, 0.0);
compositeOpacity->AddPoint(80.0, 1.0);
compositeOpacity->AddPoint(80.1, 0.0);
compositeOpacity->AddPoint(255.0, 0.0);
volumeProperty->SetScalarOpacity(compositeOpacity); // composite first.
vtkSmartPointer<vtkColorTransferFunction> color =
vtkSmartPointer<vtkColorTransferFunction>::New();
color->AddRGBPoint(0.0, 0.0, 0.0, 1.0);
color->AddRGBPoint(40.0, 1.0, 0.0, 0.0);
color->AddRGBPoint(255.0, 1.0, 1.0, 1.0);
volumeProperty->SetColor(color);
vtkSmartPointer<vtkVolume> volume =
vtkSmartPointer<vtkVolume>::New();
volume->SetMapper(volumeMapper);
volume->SetProperty(volumeProperty);
volume->SetUserTransform(volumeUserTransform);
ren1->AddViewProp(volume);
// Render composite. In default mode. For coverage.
renWin->Render();
iren->Start();
return EXIT_SUCCESS;
}
void CreateImageData(vtkImageData* imageData)
{
// Create a spherical implicit function.
vtkSmartPointer<vtkSphere> sphere =
vtkSmartPointer<vtkSphere>::New();
sphere->SetRadius(0.1);
sphere->SetCenter(0.0, 0.0, 0.0);
vtkSmartPointer<vtkSampleFunction> sampleFunction =
vtkSmartPointer<vtkSampleFunction>::New();
sampleFunction->SetImplicitFunction(sphere);
sampleFunction->SetOutputScalarTypeToDouble();
sampleFunction->SetSampleDimensions(127, 127, 127); // intentional NPOT dimensions.
sampleFunction->SetModelBounds(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
sampleFunction->SetCapping(false);
sampleFunction->SetComputeNormals(false);
sampleFunction->SetScalarArrayName("values");
sampleFunction->Update();
vtkDataArray* a = sampleFunction->GetOutput()->GetPointData()->GetScalars("values");
double range[2];
a->GetRange(range);
vtkSmartPointer<vtkImageShiftScale> t =
vtkSmartPointer<vtkImageShiftScale>::New();
t->SetInputConnection(sampleFunction->GetOutputPort());
t->SetShift(-range[0]);
double magnitude = range[1] - range[0];
if (magnitude == 0.0)
{
magnitude = 1.0;
}
t->SetScale(255.0 / magnitude);
t->SetOutputScalarTypeToUnsignedChar();
t->Update();
imageData->ShallowCopy(t->GetOutput());
}