[vtkusers] updating vtkImageAccumulate
mbcx9rb9
richard.j.brown at live.co.uk
Mon Jul 6 04:33:55 EDT 2015
That did the trick!
Thanks, seems very obvious in hindsight.
Regards,
Richard
> On 03 Jul 2015, at 19:24, Dan Lipsa-2 [via VTK] <ml-node+s1045678n5732713h75 at n5.nabble.com> wrote:
>
> Did you called Modified() on your image data? This is how downstream algorithms know to recompute their results.
>
> On Fri, Jul 3, 2015 at 4:50 AM mbcx9rb9 <[hidden email] <x-msg://2/user/SendEmail.jtp?type=node&node=5732713&i=0>> wrote:
> i have a vtkImageData, which I would like to be able to calculate the max,
> min, average, etc. via vtkImageAccumulate. Then I want to be able to edit
> the image data, update the image accumulate and see the new statistics.
>
> However, it seems that vtkImageAccumulate doesn't work how I hoped it would.
> When I change my image data, my image accumulate still returns the original
> statistics of the image data before I made the changes.
>
> If I edit my image data, am I obliged to reinitialise my image accumulate to
> be able to see the statistics on the edited image data?
>
> I have attached a simple example of a matrix with one voxel=100 and whose
> max is found with imageaccumulate. Then, a voxel of 200 is added,
> imageaccumulate is updated, but returns a max of 100 instead of the new 200.
> Finally, a new imageaccumulate is used to verify that the actually max is
> 200 as expected.
>
> Any ideas of where I'm going wrong would be greatly appreciated.
>
>
>
> // create image data
> vtkSmartPointer<vtkImageData> id = vtkSmartPointer<vtkImageData>::New();
> id->SetSpacing(1,1,1);
> id->SetExtent(0,99,0,99,0,99);
> id->AllocateScalars(VTK_DOUBLE,1);
>
> // set all values to zero
> for (int i=id->GetExtent()[0]; i<=id->GetExtent()[1]; i++) {
> for (int j=id->GetExtent()[2]; j<=id->GetExtent()[3]; j++) {
> for (int k=id->GetExtent()[4]; k<=id->GetExtent()[5]; k++) {
> double* voxel =
> static_cast<double*>(id->GetScalarPointer(i,j,k));
> voxel[0] = 0;
> }
> }
> }
>
> // set one voxel value to 100
> double* voxel = static_cast<double*>(id->GetScalarPointer(50,50,50));
> voxel[0] = 100;
>
> // set image accumulate
> vtkSmartPointer<vtkImageAccumulate> ia =
> vtkSmartPointer<vtkImageAccumulate>::New();
> ia->SetInputData(id);
> ia->SetComponentExtent(id->GetExtent());
> ia->SetComponentOrigin(id->GetOrigin());
> ia->SetComponentSpacing(id->GetSpacing());
> ia->Update();
>
> // output the max in the matrix (should be 100)
> std::cout << "max before change: " << ia->GetMax()[0] << std::endl;
>
> // change a different voxel to 200
> voxel = static_cast<double*>(id->GetScalarPointer(50,50,60));
> voxel[0] = 200;
>
> // update image accumulate
> ia->Update();
> std::cout << "max after change (want this value to be 200): " <<
> ia->GetMax()[0] << std::endl;
>
> // create second image accumulate to verify that the max is, as it
> should be, 200
> vtkSmartPointer<vtkImageAccumulate> ia2 =
> vtkSmartPointer<vtkImageAccumulate>::New();
> ia2->SetInputData(id);
> ia2->SetComponentExtent(id->GetExtent());
> ia2->SetComponentOrigin(id->GetOrigin());
> ia2->SetComponentSpacing(id->GetSpacing());
> ia2->Update();
> std::cout << "max with ia2 (should be 200): " << ia2->GetMax()[0] <<
> std::endl;
>
>
>
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