Move ImageData To Make Center As Origin Point

We can find that vtkImageActor object will display image with controling its position with the bottom left corner of the image by the default way.

Test project:

#include <vtkTransformFilter.h>
#include <vtkImageData.h>
#include <iostream>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkActor.h>
#include <vtkConeSource.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkTextSource.h>
#include <vtkAxesActor.h>
#include <vtkImageActor.h>
#include <vtkPNGReader.h>
#include <vtkTransform.h>
#include <vtkFollower.h>
#include <vtkImageMapper.h>
#include <vtkBillboardTextActor3D.h>
#include <vtkJPEGReader.h>
#include <vtkImageSlice.h>
#include <vtkImageMapper3D.h>
#include <vtkCamera.h>
#include <vtkImageProperty.h>

#define vtkSPtr vtkSmartPointer
#define vtkSPtrNew(Var, Type) vtkSPtr<Type> Var = vtkSPtr<Type>::New();

using namespace std;


int main()
{
    vtkSPtrNew( reader, vtkPNGReader );
    reader->SetFileName( "screenshot.png" );
    reader->Update();

    vtkSmartPointer<vtkImageData> imgData = reader->GetOutput();

    vtkSPtrNew( imgActor, vtkImageActor );
    imgActor->SetInputData( imgData );
    imgActor->SetScale( 0.1 );

    vtkSmartPointer<vtkAxesActor> axes = vtkSmartPointer<vtkAxesActor>::New();
    axes->AxisLabelsOff();
    axes->SetTotalLength( 3, 3, 3 );

    vtkSPtrNew( renderer, vtkRenderer );
    renderer->AddActor( axes );
    renderer->AddActor( imgActor );
    renderer->SetBackground( 0, 0, 0 );

    vtkSPtrNew( renderWindow, vtkRenderWindow );
    renderWindow->AddRenderer( renderer );

    vtkSPtrNew( renderWindowInteractor, vtkRenderWindowInteractor );
    renderWindowInteractor->SetRenderWindow( renderWindow );

    renderer->ResetCamera();

    renderer->ResetCamera();
    renderWindow->Render();
    renderWindowInteractor->Start();
    return 0;
}

Result:

How to make the image’s center as actor’s position? Just as rewrite 3D model to make center as (0,0,0), related post: https://www.weiy.city/2022/01/rewrite-file-to-move-3d-model-to-origin-point/

Let’s change imageData:

    vtkSmartPointer<vtkImageData> imgData = reader->GetOutput();
    double *bds = imgData->GetBounds();
    imgData->SetOrigin( -(bds[0]+bds[1])*0.5, -(bds[2]+bds[3])*0.5, -(bds[4]+bds[5])*0.5 );

New result: