[vtkusers] Multiple iso-surfaces generated from labelled volume: smoothing & coloring

Weiguang Guan guanw at rhpcs.mcmaster.ca
Thu Dec 2 17:05:33 EST 2004

Hi VTK users,

Maybe someone could help improve the rendering of multiple objects. I have 
a labelled volume (0: background; 1: bone, 2: muscle; ...), and want to 
display them with different colors. 

What I did is looping through the number of objects (or number of labels), 
in each loop i
	(1) threshold to get label i
	(2) vtkContourFilter
	(3) vtkWindowedSincPolyDataFilter
	(4) vtkPolyDataNormals
	(5) vtkPolyDataMapper
	(6) vtkActor
	(7) Set a specific color to the actor
The problem is that some objects penetrate (or overlap) others after 
deformation (vtkWindowedSincPolyDataFilter). I am afraid that I will have 
the same problem if I use vtkDiscreteMarchingCubes instead of multiple 
usage of vtkContourFilter.

Perhaps, a better way is to extract an "outmost" surface at iso-value = 
0.5 and omit the interfaces between objects. Then how to color different 
patches of the surface that correspond to different objects?

Thank you very much in advance.


Weiguang Guan, Research Engineer
RHPCS, McMaster University

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