[vtkusers] No vectors in input data after ShallowCopy

[Cory Quammen]

Hi Werner,

Consider this line.

newImage->GetPointData()->SetActiveVectors("imageScalars");

Where is an array named "imageScalars"? I don't see that anywhere in the
code, so whatever active vectors there might be in the image are being
unset by the call above.

After you allocate the scalars, you can give them a name with something like

newImage->GetPointData()->GetArray(0)->SetName("imageScalars");

Or you can skip naming the array and set the active vectors with

newImage->GetPointData()->SetVectors(newImage->GetPointData()->GetArray(0));

HTH,
Cory

On Wed, Oct 28, 2015 at 11:03 AM, Werner Sembach <werner at sembach.de> wrote:

> So i have a function that gehts a vtkImageData*
> and should replace another, already displayed, vtkImageData*
>
> void MainWindow::updateImage(vtkSmartPointer<vtkImageData> newImage) {
>     image->ShallowCopy(newImage);
>     image->Modified();
>
>     qvtkWidget->GetRenderWindow()->Render();
> }
>
> however when i try to run this i get the error "vtkHedgeHog (0xa3fc80): No
> vectors in input data"
>
> if i use a standart assignment (image = newImage) the display doesn't
> change at all
>
>
>
> initial image is created here (image is a instance variable):
>
> void MainWindow::initializeImage()
> {
>     unsigned int dim = 20;
>
>     image->SetDimensions(dim, dim, 1);
>     image->SetSpacing(1.0, 1.0, 1.0);
>     image->SetOrigin(0.0, 0.0, 0.0);
>
>     image->AllocateScalars(VTK_DOUBLE,3);
>
>     for(unsigned int x = 0; x < dim; x++)
>     {
>         for(unsigned int y = 0; y < dim; y++)
>         {
>             double* pixel =
> static_cast<double*>(image->GetScalarPointer(x,y,0));
>             pixel[0] = -1;
>             pixel[1] = 1;
>             pixel[2] = 0.0;
>         }
>     }
>     image->GetPointData()->SetActiveVectors("ImageScalars");
>     image->Modified();
> }
>
> the new image is generated here:
>
> void MainWindow::on_actionTest_Update_triggered()
> {
>     vtkSmartPointer<vtkImageData> newImage =
> vtkSmartPointer<vtkImageData>::New();
>     unsigned int dim = 30;
>
>     newImage->SetDimensions(dim, dim, 1);
>     newImage->SetSpacing(1.0, 1.0, 1.0);
>     newImage->SetOrigin(0.0, 0.0, 0.0);
>
>     newImage->AllocateScalars(VTK_DOUBLE,3);
>
>     for(unsigned int x = 0; x < dim; x++)
>     {
>         for(unsigned int y = 0; y < dim; y++)
>         {
>             double* pixel =
> static_cast<double*>(newImage->GetScalarPointer(x,y,0));
>             pixel[0] = 1;
>             pixel[1] = 0.0;
>             pixel[2] = 0.0;
>         }
>     }
>     newImage->GetPointData()->SetActiveVectors("imageScalars");
>     newImage->Modified();
>     updateImage(newImage);
> }
>
>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
>
> Search the list archives at: http://markmail.org/search/?q=vtkusers
>
> Follow this link to subscribe/unsubscribe:
> http://public.kitware.com/mailman/listinfo/vtkusers
>
>


-- 
Cory Quammen
R&D Engineer
Kitware, Inc.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20151028/17e42b05/attachment.html>