[vtkusers] Strange Problem with vtkImageReslice for 2D rotation

[Thomas Zhang]

Sorry, in the code I posted, the 3rd and 4th lines to force all the input hard-coded have mistakes.  They should be:

            memset(pInImageData, 0, sizeof (float)*nOriginalWidth*nOriginalHeight);     //make it a blank image.
            float fAngle = 0.2;       //hard code the input, angle = 0.2 instead of 0.02

Could anyone please help?  This could potentially be a problem in VTK itself as the exact same inputs give totally different results!

I have also tried the latest version of vtk 5.4.2 and it gives me the same problem.

Thomas
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From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On Behalf Of Thomas Zhang
Sent: Thursday, June 11, 2009 12:16 PM
To: vtkusers at vtk.org
Subject: [vtkusers] Strange Problem with vtkImageReslice for 2D rotation

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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