[vtkusers] Voxel Data from MATLAB to VTK

[David Gobbi]

Just a comment... don't use variable names like "vtkImage" and
"vtkArray".  If you do, then you will get conflicts between the names
of your variables and the names of VTK classes.

   David


On Mon, May 17, 2010 at 2:25 PM, Brian Davis <bitminer at gmail.com> wrote:
>
> -snip from David-
> My familiarity with Titan is nil, but "git blame" tells me that the
> vtkMatlabMexAdapter.h has been in VTK since 2009-12-14.  It should be
> built whenever VTK_USE_MATLAB_MEX is turned ON in CMake.
> -end snip-
>
> I searched my tree which includes vtk-5.4 source and there is no
> vtkMatlabMexAdapter.h file nor is there any text in files with
> "vtkMatlabMexAdapter".  So I think this maybe new at least post 5.4 (the
> version I am using).  Not sure why git is reporting this.  I did not check
> git for when this was added to release.
>
> A search for vtkMatlabMexAdapter in
> http://www.vtk.org/doc/release/5.4/html/classes.html
> returns nada, zippo, nil, none, zero.
>
> A search for vtkMatlabMexAdapter in
> http://www.vtk.org/doc/release/5.6/html/classes.html
> returns ... ding ding ding we have a winner!
>
> My familularity with Titan is also nil except for my little readings on the
> topic and this pdf if your interested
> http://titan.sandia.gov/media/Information_Visualization_in_VTK.pdf.  It's
> got pretty pictures :-)
>
> https://www.kitware.com/InfovisWiki/index.php/Main_Page
>
> -snip from Thomas-
> I am the main developer of the Matlab Engine related code in VTK.
>
> Yes, vtkMatlabMexAdapter is the class you need to convert data from VTK to
> the Matlab mxArray type and back again.   This class will get compiled when
> VTK_USE_MATLAB_MEX is turned on in the Cmake advanced options of VTK.
>
> Are you are trying to build a Matlab mex program (shared library) that takes
> input Matlab data and sends it to VTK, and then returns data from VTK to
> Matlab?
>
> -end snip-
>
> Yes I am trying to build a Matlab mex program (shared library) that takes
> input from Matlab and sends to VTK.  I have this somewhat working and I
> think I was able (I am currently verifying) to get this to work in 5.4
> without the vtkMatlabMexAdapter, though this seems a much easier approach so
> I may very well upgrade to 5.6 and beyond.  The code snipit that I currently
> somewhat have working with 5.4 is
>
> -snip-
> ...
>
>     for (int i = 0; i < nrhs; i++)
>     {
>
>         if( mxGetNumberOfDimensions( prhs[i] ) != 3 )
>         {
>             mexErrMsgTxt("Render volume can only accept matrix of 3
> dimensions");
>             return;
>         }
>
>         // Get the dimensions
>         const mwSize* matDimensions = mxGetDimensions( prhs[i] );
>
>         y_dim = matDimensions[0];
>         x_dim = matDimensions[1];
>         z_dim = matDimensions[2];
>
>         mexPrintf( "y_dim = %d, x_dim = %d, z_dim = %d \n", y_dim, x_dim,
> z_dim );
>
>         // Get the data
>         volumeData = mxGetPr(prhs[i]);
>     }
>
> ...
>     vtkSmartPointer<vtkDoubleArray> vtkArray =
> vtkSmartPointer<vtkDoubleArray>::New();
>
>     vtkArray->SetVoidArray( (void *) volumeData, y_dim*x_dim*z_dim , 0);
>
>     vtkSmartPointer<vtkImageData> vtkImage =
> vtkSmartPointer<vtkImageData>::New();
>
>     vtkImage->SetDimensions( numeric_cast<int>(y_dim) ,
> numeric_cast<int>(x_dim), numeric_cast<int>(z_dim) );
>     vtkImage->SetSpacing(1.0, 1.0, 1.0);
>     vtkImage->SetOrigin(0.0, 0.0, 0.0);
>
>     vtkImage->GetPointData()->SetScalars(vtkArray);
>
>     volumeMapper->SetInput( vtkImage );
>
>     // set the volume mapper.
>     volume->SetMapper( volumeMapper );
>
> -snip-
>
> The term *somewhat* is defined there to mean: that I can see my volume, but
> it locks up Matlab and vtk render window.
>
> Thanks David and Thomas for the input.
>
> Brian
>
>