[vtkusers] Strange Problem with vtkImageReslice for 2D rotation

[Thomas Zhang]

I have this code below to do 2D image rotation.  Strangely, even if I force all the input value as hard coded, it will give me different answers at different times.

The output at the last lines, nNewWidth is sometimes 2055, sometimes 1, which is totally wrong.  The 1st time it's always 1.  Can anyone help?

The vtk version is 5.0.4.

Thanks!
Thomas

            int nOriginalWidth = 2048, nOriginalHeight=2048; //hard code the input.
            float* pInImageData = new float[nOriginalWidth*nOriginalHeight];
            memset(pInImageData, sizeof (float)*nOriginalWidth*nOriginalHeight);
            float fAngle = 0.02; //hard code the input.

            vtkFloatArray *pFltArray1 = vtkFloatArray::New();
            pFltArray1->SetVoidArray(pInImageData,nOriginalWidth*nOriginalHeight,1);


            vtkImageData *pvtkImageData1;
            pvtkImageData1= vtkImageData::New();
            pvtkImageData1->SetDimensions(nOriginalWidth,nOriginalHeight,1);
            pvtkImageData1->SetScalarTypeToFloat();
            pvtkImageData1->SetNumberOfScalarComponents(1);
            pvtkImageData1->GetPointData()->SetScalars(pFltArray1);


            vtkTransform *pTransForm = vtkTransform::New();
            pTransForm->RotateZ(fAngle);
            double points1[3]={1,0,0};
            double points2[3]={0,1,0};
            double points3[3]={0,0,1};

            pTransForm->TransformPoint(points1,points1);
            pTransForm->TransformPoint(points2,points2);
            pTransForm->TransformPoint(points3,points3);

            vtkImageReslice  *pImageReslice = vtkImageReslice::New();
            pImageReslice->SetResliceAxesDirectionCosines(points1,points2,points3);
            pImageReslice->SetInput(pvtkImageData1);

            int nExtent[6];
            pvtkImageData1->GetExtent(nExtent);

            pImageReslice->SetResliceAxesOrigin((nExtent[1]-nExtent[0])/2.0,(nExtent[3]-nExtent[2])/2.0,0);
            pImageReslice->SetOutputExtentToDefault();
            pImageReslice->SetOutputOriginToDefault();
            pImageReslice->GetOutput()->SetUpdateExtentToWholeExtent();
            pImageReslice->MirrorOn ();
            pImageReslice->AutoCropOutputOn();
            pImageReslice->InterpolateOn();
            pImageReslice->Update();

            vtkImageData *pvtkOutImageData = pImageReslice->GetOutput();

            float *pOutData = (float*)pvtkOutImageData->GetScalarPointer();
            int nDim[3];
            pvtkOutImageData->GetDimensions(nDim);

            nNewWidth = nDim[0];
            assert(nNewWidth> nOriginalWidth);

            //ERROR: sometimes nNewWidth is 1; sometimes it's 2055.

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