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

[Liam Kurmos]

I forgot to reference in my last post your example:

http://www.cmake.org/Wiki/VTK/Examples/IterateImageData

which is the way i do it now.

I was thinking there may be a method that lets you set a 3D array as
scalars that might be faster for performance critical tasks but
haven't needed to do that yet.

Liam


On Wed, Feb 10, 2010 at 12:39 PM, David Doria <daviddoria+vtk at gmail.com> wrote:
> 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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