[vtkusers] A problem about vtkImageData and Project

[周敏明]

Hello everyone,
       I met a problem about "vtkImageData". My input is a 3D point, a .BMP
file and a Matrix.  The matrix can transform my 3D position to 2D position.
I want to find the vtkIdType of the point on the BMP file, so that I can get
the color of the point. So I write some code to implement this, but it's not
going well.

    vtkBMPReader *bmp = vtkBMPReader::New();
    bmp->SetFileName(filename);
    bmp->Update();
    vtkImageData *image = bmp->GetOutput();

// x, y is the 2D position on the BMP file;
    vtkIdType id = image->FindPoint(x, y, 0);
    std::cout<<"Find ID:"<<id<<std::endl;
    vtkUnsignedCharArray *color = (vtkUnsignedCharArray
*)image->GetPointData()->GetScalars();
    double rgb[3] = {0};
    color->GetTupleValue(id, rgb);

    The output of my code is: "Find ID: -1". So I can not get the right
color. Is there anyone can help me? You assistance will be great appreciate.


    Sorry for my bad English.
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