[vtkusers] Modifying Medical1.cxx to use images already in memory

[Norman Young]

Hi,

I'm new to VTK and have what seems to be a pretty basic question.  I'm
trying to modify the Medical1.cxx sample so that instead of reading
from disk using vtkVolume16Reader, it uses pixel data that I already
have in memory in my application. What might be the best way of doing
that?

So far, I've created (I think) a volume with vtkImageData, then tried
to set the input on the vtkContourFilter to the volume.  It looks
something like this (BTW, I'm using C#):

vtkImageData volumeData = new vtkImageData();

[fill volumeData with some data here]

vtkContourFilter skinExtractor = new vtk.vtkContourFilter();
skinExtractor.SetInput(volumeData);
skinExtractor.SetValue(0, 500);
vtkPolyDataNormals skinNormals = new vtk.vtkPolyDataNormals();
skinNormals.SetInputConnection(skinExtractor.GetOutputPort());

[rest of the sample code here]

When I run this, I get this error:

ERROR: In ..\..\vtk\Graphics\vtkPolyDataNormals.cxx, line 94
vtkPolyDataNormals (060B7520): No data to generate normals for!

I assume this is related to not setting the input to the contour
filter correctly.  My very vague understanding of the pipeline is that
I should be using vtkAlgorithm and input/output ports, but I'm rather
confused at how that might work with vtkImageData.

Thanks in advance for any help anyone might be able to provide!

Norman