ImageAlgorithmFilter
vtk-examples/Cxx/Developers/ImageAlgorithmFilter
Description¶
This example demonstrates how to setup the pipeline for a {{class vtkImageAlgorithm}} filter that takes a {{class vtkImageData}} as input and produces another vtkImageData as output. This particular example creates a 2x2 image and fills it with "2"s. The filter changes the (0,0) element to a 5.
Question
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Code¶
ImageAlgorithmFilter.cxx
#include <vtkSmartPointer.h>
#include "vtkImageAlgorithmFilter.h"
#include <vtkImageData.h>
void PrintImage(vtkImageData* image);
int main (int /* argc */, char * /* argv */ [])
{
vtkSmartPointer<vtkImageData> input =
vtkSmartPointer<vtkImageData>::New();
// Setup the image
input->SetDimensions(2,2,1);
input->AllocateScalars(VTK_DOUBLE,1);
// Fill every entry of the image data with "2.0"
int* dims = input->GetDimensions();
for (int y=0; y<dims[1]; y++)
{
for (int x=0; x<dims[0]; x++)
{
input->SetScalarComponentFromDouble(x,y,0,0,2.0);
}
}
std::cout << "Input image: " << std::endl;
PrintImage(input);
vtkSmartPointer<vtkImageAlgorithmFilter> filter =
vtkSmartPointer<vtkImageAlgorithmFilter>::New();
filter->SetInputData(input);
filter->Update();
vtkImageData* output = filter->GetOutput();
std::cout << "Output image: " << std::endl;
PrintImage(output);
return 0;
}
void PrintImage(vtkImageData* image)
{
int* dims = image->GetDimensions();
for (int y=0; y<dims[1]; y++)
{
for (int x=0; x<dims[0]; x++)
{
double v = image->GetScalarComponentAsDouble(x,y,0,0);
std::cout << v << " ";
}
std::cout << std::endl;
}
}
vtkImageAlgorithmFilter.h
#ifndef __vtkImageAlgorithmFilter_h
#define __vtkImageAlgorithmFilter_h
#include <vtkImageAlgorithm.h>
class vtkImageAlgorithmFilter : public vtkImageAlgorithm
{
public:
static vtkImageAlgorithmFilter *New();
vtkTypeMacro(vtkImageAlgorithmFilter,vtkImageAlgorithm);
vtkImageAlgorithmFilter(){}
protected:
int RequestData(vtkInformation *, vtkInformationVector **, vtkInformationVector *) override;
private:
vtkImageAlgorithmFilter(const vtkImageAlgorithmFilter&); // Not implemented.
void operator=(const vtkImageAlgorithmFilter&); // Not implemented.
};
#endif
vtkImageAlgorithmFilter.cxx
#include "vtkImageAlgorithmFilter.h"
#include <vtkImageData.h>
#include <vtkObjectFactory.h>
#include <vtkStreamingDemandDrivenPipeline.h>
#include <vtkInformationVector.h>
#include <vtkInformation.h>
#include <vtkDataObject.h>
#include <vtkSmartPointer.h>
vtkStandardNewMacro(vtkImageAlgorithmFilter);
int vtkImageAlgorithmFilter::RequestData(vtkInformation *vtkNotUsed(request),
vtkInformationVector **inputVector,
vtkInformationVector *outputVector)
{
// Get the info objects
vtkInformation *inInfo = inputVector[0]->GetInformationObject(0);
vtkInformation *outInfo = outputVector->GetInformationObject(0);
// Get the input and ouptut
vtkImageData *input = dynamic_cast<vtkImageData*>(
inInfo->Get(vtkDataObject::DATA_OBJECT()));
vtkImageData *output = dynamic_cast<vtkImageData*>(
outInfo->Get(vtkDataObject::DATA_OBJECT()));
vtkSmartPointer<vtkImageData> image =
vtkSmartPointer<vtkImageData>::New();
image->ShallowCopy(input);
image->SetScalarComponentFromDouble(0,0,0,0, 5.0);
output->ShallowCopy(image);
// Without these lines, the output will appear real but will not work as the input to any other filters
int extent[6];
input->GetExtent(extent);
output->SetExtent(extent);
outInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT(),
extent,
6);
outInfo->Set(vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(),
extent,
6);
return 1;
}
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.3 FATAL_ERROR)
project(ImageAlgorithmFilter)
find_package(VTK COMPONENTS
vtkCommonCore
vtkCommonDataModel
QUIET
)
if (NOT VTK_FOUND)
message("Skipping ImageAlgorithmFilter: ${VTK_NOT_FOUND_MESSAGE}")
return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
# old system
include(${VTK_USE_FILE})
add_executable(ImageAlgorithmFilter MACOSX_BUNDLE ImageAlgorithmFilter.cxx )
target_link_libraries(ImageAlgorithmFilter PRIVATE ${VTK_LIBRARIES})
else ()
# include all components
add_executable(ImageAlgorithmFilter MACOSX_BUNDLE ImageAlgorithmFilter.cxx )
target_link_libraries(ImageAlgorithmFilter PRIVATE ${VTK_LIBRARIES})
# vtk_module_autoinit is needed
vtk_module_autoinit(
TARGETS ImageAlgorithmFilter
MODULES ${VTK_LIBRARIES}
)
endif ()
Download and Build ImageAlgorithmFilter¶
Click here to download ImageAlgorithmFilter and its CMakeLists.txt file. Once the tarball ImageAlgorithmFilter.tar has been downloaded and extracted,
cd ImageAlgorithmFilter/build
If VTK is installed:
cmake ..
If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:
cmake -DVTK_DIR:PATH=/home/me/vtk_build ..
Build the project:
make
and run it:
./ImageAlgorithmFilter
WINDOWS USERS
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.