[vtkusers] Re-post: how to use own 3d array to create image

[David Doria]

On Wed, Feb 10, 2010 at 5:31 AM, Liam Kurmos <quantum.leaf at googlemail.com>wrote:

> Hi,
>
> I'm still pretty new to vtk myself and not 100% sure if this is what
> you want but have a look at the code below. I think i adapted it from
> the guide. If it's useful i could make an example.
>
>    int xDim, yDim,zDim;
>    xDim=yDim=zDim=26;
>    float z,y,x,kOffset,jOffset,offset;
>    vtkImageData *vol = vtkImageData::New();
>    vol->SetDimensions(xDim,yDim,zDim);
>    vol->SetOrigin(-1,-1,-1);
>
>    float sp=(float)1.0/(xDim-1);
>    vol->SetSpacing(sp,sp,sp);
>
>    vtkFloatArray *scalars=vtkFloatArray::New();
>    for (int k=0;k<zDim;k++){
>
>        z=-0.5+k*sp;
>        kOffset= k*xDim*yDim;
>        for(int j=0;j<yDim;j++){
>            y=-0.5+j*sp;
>            jOffset=j*xDim;
>            for (int i=0;i<xDim;i++){
>                x=-0.5+i*sp;
>                float s=x*x+y*y+z*z-(0.4*0.4);
>
>                offset=i+jOffset+kOffset;
>                scalars->InsertTuple1(offset,s);
>            }
>        }
>    }
>
>    vol->GetPointData()->SetScalars(scalars);
>
>    scalars->Delete();
>
>    vtkMarchingCubes *iso = vtkMarchingCubes::New();
>    iso->SetInput(vol);
>    iso->SetNumberOfContours(1);
>    iso->SetValue(0, 0);
>
> Liam
>

I believe you could also do this ( can't try it right now)

double* volValue = static_cast<double*>vol->GetScalarPointer(i, j, k);
volValue = whatever you want pixel (x,y,z) to equal

Setting pixels in linear order always just seems to me like it is asking for
trouble :) This method (if it is legitimate) lets you set the pixels via
their position in the image.

Thanks,

David
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