[yt-users] VTK how to Import 3D image data via imageImport on c++ for Volume Rendering
John Zuhone
jzuhone at gmail.com
Thu Oct 13 10:56:54 PDT 2016
Hi Honghe,
I think you sent this to the wrong mailing list, this is the yt list.
However, if you ever have any questions for us, please feel free to ask!
Best,
John ZuHone
> On Oct 12, 2016, at 10:46 PM, Honghe <397667796 at qq.com> wrote:
>
>
>
> down vote
> <>favorite
> <http://stackoverflow.com/questions/39976669/vtk-how-to-import-3d-image-data-via-imageimport-on-c#>
> Thanks for VTK first, it is a nice Tool. But I meet a problem as follow.
>
> Through VTK Python API, I can import/make 3d image data and Volume Rendering as follow:
>
> <http://i.stack.imgur.com/sslIo.png>
> And the Python code is:
>
> # coding=utf-8
> import vtk
> from numpy import *
> import random
>
> num = 74
> # We begin by creating the data we want to render.
> # For this tutorial, we create a 3D-image containing three overlaping cubes.
> # This data can of course easily be replaced by data from a medical CT-scan or anything else three dimensional.
> # The only limit is that the data must be reduced to unsigned 8 bit or 16 bit integers.
> data_matrix = zeros([num, num, num], dtype=uint8)
> # data_matrix[0:35, 0:35, 0:35] = 50
> # data_matrix[25:55, 25:55, 25:55] = 100
> # data_matrix[45:74, 45:74, 45:74] = 150
>
> for i in range(0, num - 1):
> for j in range(0, num - 1):
> for k in range(0, num - 1):
> data_matrix[i:i + 1, j:j + 1, k:k + 1] = 100
>
> # For VTK to be able to use the data, it must be stored as a VTK-image. This can be done by the vtkImageImport-class which
> # imports raw data and stores it.
> dataImporter = vtk.vtkImageImport()
> # The preaviusly created array is converted to a string of chars and imported.
> data_string = data_matrix.tostring()
> # dataImporter.CopyImportVoidPointer(data_string, len(data_string))
> dataImporter.SetImportVoidPointer(data_matrix)
> # The type of the newly imported data is set to unsigned char (uint8)
> dataImporter.SetDataScalarTypeToUnsignedChar()
> # Because the data that is imported only contains an intensity value (it isnt RGB-coded or someting similar), the importer
> # must be told this is the case.
> dataImporter.SetNumberOfScalarComponents(1)
> # The following two functions describe how the data is stored and the dimensions of the array it is stored in. For this
> # simple case, all axes are of length 75 and begins with the first element. For other data, this is probably not the case.
> # I have to admit however, that I honestly dont know the difference between SetDataExtent() and SetWholeExtent() although
> # VTK complains if not both are used.
> dataImporter.SetDataExtent(0, 74, 0, 74, 0, 74)
> dataImporter.SetWholeExtent(0, 74, 0, 74, 0, 74)
>
> # The following class is used to store transparencyv-values for later retrival. In our case, we want the value 0 to be
> # completly opaque whereas the three different cubes are given different transperancy-values to show how it works.
> alphaChannelFunc = vtk.vtkPiecewiseFunction()
> alphaChannelFunc.AddPoint(0, 0.0)
> # alphaChannelFunc.AddPoint(50, 0.001)
> # alphaChannelFunc.AddPoint(100, 0.02)
> alphaChannelFunc.AddPoint(150, 0.02)
>
> # This class stores color data and can create color tables from a few color points. For this demo, we want the three cubes
> # to be of the colors red green and blue.
> colorFunc = vtk.vtkColorTransferFunction()
> colorFunc.AddRGBPoint(50, 0.0, 0.2, 0.2)
> colorFunc.AddRGBPoint(100, 0.0, 1.0, 0.0)
> colorFunc.AddRGBPoint(150, 0.0, 0.0, 1.0)
>
> # The preavius two classes stored properties. Because we want to apply these properties to the volume we want to render,
> # we have to store them in a class that stores volume prpoperties.
> volumeProperty = vtk.vtkVolumeProperty()
> volumeProperty.SetColor(colorFunc)
> volumeProperty.SetScalarOpacity(alphaChannelFunc)
>
> # This class describes how the volume is rendered (through ray tracing).
> compositeFunction = vtk.vtkVolumeRayCastCompositeFunction()
> # We can finally create our volume. We also have to specify the data for it, as well as how the data will be rendered.
> volumeMapper = vtk.vtkVolumeRayCastMapper()
> volumeMapper.SetVolumeRayCastFunction(compositeFunction)
> volumeMapper.SetInputConnection(dataImporter.GetOutputPort())
>
> # The class vtkVolume is used to pair the preaviusly declared volume as well as the properties to be used when rendering that volume.
> volume = vtk.vtkVolume()
> volume.SetMapper(volumeMapper)
> volume.SetProperty(volumeProperty)
>
> # With almost everything else ready, its time to initialize the renderer and window, as well as creating a method for exiting the application
> renderer = vtk.vtkRenderer()
> renderWin = vtk.vtkRenderWindow()
> renderWin.AddRenderer(renderer)
> renderInteractor = vtk.vtkRenderWindowInteractor()
> renderInteractor.SetRenderWindow(renderWin)
>
> # We add the volume to the renderer ...
> renderer.AddVolume(volume)
> # ... set background color to white ...
> renderer.SetBackground(1, 1, 1)
> # ... and set window size.
> renderWin.SetSize(400, 400)
>
>
> # A simple function to be called when the user decides to quit the application.
> def exitCheck(obj, event):
> if obj.GetEventPending() != 0:
> obj.SetAbortRender(1)
>
>
> # Tell the application to use the function as an exit check.
> # renderWin.AddObserver("AbortCheckEvent", exitCheck)
>
> renderInteractor.Initialize()
> # Because nothing will be rendered without any input, we order the first render manually before control is handed over to the main-loop.
> renderWin.Render()
> renderInteractor.Start()
> But for c++ API, I can not get the same Volume Rendering through ImageImport.
>
> The following code is the C++ code I write refer to the above Python code. But the result is as follow：
>
> <http://i.stack.imgur.com/cCF9w.png>
> the C++ code I write refer to the above Python code:
>
> #include <iostream>
> #include <vtkStructuredPointsReader.h>
> #include <vtkVolumeRayCastCompositeFunction.h>
> #include <vtkVolumeRayCastMapper.h>
> #include <vtkRendererCollection.h>
> #include <vtkSmartPointer.h>
> #include <vtkImageImport.h>
> #include <stdlib.h>
> // VTK includes
> #include "vtkBoxWidget.h"
> #include "vtkCamera.h"
> #include "vtkCommand.h"
> #include "vtkColorTransferFunction.h"
> #include "vtkDICOMImageReader.h"
> #include "vtkImageData.h"
> #include "vtkImageResample.h"
> #include "vtkMetaImageReader.h"
> #include "vtkPiecewiseFunction.h"
> #include "vtkPlanes.h"
> #include "vtkProperty.h"
> #include "vtkRenderer.h"
> #include "vtkRenderWindow.h"
> #include "vtkRenderWindowInteractor.h"
> #include "vtkVolume.h"
> #include "vtkVolumeProperty.h"
> #include "vtkXMLImageDataReader.h"
> #include "vtkFixedPointVolumeRayCastMapper.h"
>
> int main() {
> std::cout << "Hello, World!" << std::endl;
> // create data
> // Create a c-style image
> const int width = 4;
> const int height = 4;
> const int depth = 4;
>
> unsigned char cImage[width * height * depth];
> unsigned char value = 0;
> for (unsigned int row = 0; row < height; ++row) {
> for (unsigned int col = 0; col < width; ++col) {
> for (unsigned int z = 0; z < depth; ++z) {
> cImage[row * width * depth + col * depth + z] = 100;
> }
> }
> }
> // Convert the c-style image to a vtkImageData
> vtkSmartPointer<vtkImageImport> imageImport =
> vtkSmartPointer<vtkImageImport>::New();
>
> imageImport->SetImportVoidPointer(cImage);
> imageImport->SetDataScalarTypeToUnsignedChar();
> imageImport->SetNumberOfScalarComponents(1);
> imageImport->SetDataSpacing(1, 1, 1);
> imageImport->SetDataOrigin(0, 0, 0);
> imageImport->SetDataExtent(0, width - 1, 0, height - 1, 0, depth - 1);
> imageImport->SetWholeExtent(0, width - 1, 0, height - 1, 0, depth - 1);
> // imageImport->SetDataExtentToWholeExtent();
> // imageImport->SetDataScalarTypeToUnsignedChar();
> // imageImport->SetNumberOfScalarComponents(1);
> imageImport->Update();
>
> // Create the standard ren, render window and interactor
> vtkRenderer *ren = vtkRenderer::New();
> vtkRenderWindow *renWin = vtkRenderWindow::New();
> renWin->AddRenderer(ren);
> vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
>
> iren->SetRenderWindow(renWin);
>
> // Create the reader for the data
> // vtkStructuredPointsReader *reader = vtkStructuredPointsReader::New();
> // reader->SetFileName("/home/honhe/ClionProjects/Demo_vtk_SimpleRayCast/ironProt.vtk");
>
> // Create transfer mapping scalar value to opacity
> vtkPiecewiseFunction *opacityTransferFunction = vtkPiecewiseFunction::New();
> opacityTransferFunction->AddPoint(0, 0.0);
> opacityTransferFunction->AddPoint(150, 0.2);
>
> // Create transfer mapping scalar value to color
> vtkColorTransferFunction *colorTransferFunction = vtkColorTransferFunction::New();
> colorTransferFunction->AddRGBPoint(0.0, 0.0, 0.0, 0.0);
> colorTransferFunction->AddRGBPoint(100.0, 0.0, 1.0, 0.0);
>
> // The property describes how the data will look
> vtkVolumeProperty *volumeProperty = vtkVolumeProperty::New();
> volumeProperty->SetColor(colorTransferFunction);
> volumeProperty->SetScalarOpacity(opacityTransferFunction);
> volumeProperty->ShadeOn();
> volumeProperty->SetInterpolationTypeToLinear();
>
> // The mapper / ray cast function know how to render the data
> vtkVolumeRayCastCompositeFunction *compositeFunction = vtkVolumeRayCastCompositeFunction::New();
> vtkVolumeRayCastMapper *volumeMapper = vtkVolumeRayCastMapper::New();
> volumeMapper->SetVolumeRayCastFunction(compositeFunction);
> volumeMapper->SetInputConnection(imageImport->GetOutputPort());
>
> // The volume holds the mapper and the property and
> // can be used to position/orient the volume
> vtkVolume *volume = vtkVolume::New();
> volume->SetMapper(volumeMapper);
> volume->SetProperty(volumeProperty);
>
> ren->AddVolume(volume);
> ren->SetBackground(1, 1, 1);
> renWin->SetSize(400, 400);
>
> iren->Initialize();
> renWin->Render();
> iren->Start();
> return 0;
> }
> And I search example code, but only find the following, they can not work with 3d image data.
>
> This example show how to import 2d Image VTK/Examples/Cxx/Images/ImageImport <http://www.vtk.org/Wiki/VTK/Examples/Cxx/Images/ImageImport>
> And this example show how to deal with 3d image, but the API is out of date This example demonstrates how to set and access locations in a 3D image. <http://www.vtk.org/Wiki/VTK/Examples/Cxx/ImageData/IterateImageData>
> This problem also post in http://stackoverflow.com/questions/39976669/vtk-how-to-import-3d-image-data-via-imageimport-on-c, but no responce right now.
>
> Any help appreciate!
>
> ------------------
> Honghe
>
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> yt-users at lists.spacepope.org
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