[vtk-developers] Problem writing out 'hollow' contours in rtstructs
david.gobbi at gmail.com
Mon Dec 20 19:52:27 EST 2010
It is possible to use vtkDelaunay2D to do a triangulation of the hollow
contours so that they can be rendered. In straight OpenGL, another
option is to use gluTesselate.
On Mon, Dec 20, 2010 at 5:25 PM, Mark Roden <mmroden at gmail.com> wrote:
> Hi all,
> I've got a problem writing out RTStruct objects using GDCM. The
> problem isn't with GDCM or VTK as they stand now, but rather with a
> particular section of the DICOM standard (3.3-2009 C 220.127.116.11). The
> problem has to do with a 'hollow' contour, or a polygon entirely
> encompassed within another polygon.
> To quote:
> When a single ROI describes an excluded inner volume, this can be
> encoded with a single contour, using a “keyhole” technique. In this
> method, an arbitrarily narrow channel is used to connect the outer
> contour to the inner contour, so that it is drawn as a single contour.
> An example of such a structure is shown in Figure C.8.8.6-1.
> If I have a set of vtkPolyData objects on a particular plane, is there
> an easy way to accomplish the above functionality?
> As I understand it, vtkPolyData are (or can be) oriented glyphs that
> indicate how a polygon should be drawn. If I were to just connect any
> two polydata objects, I'd imagine that would would need to be
> reversed. Is that understanding correct?
> Or if I made a binary representation of the mask that had a hollow in
> it, is there a way to indicate to the marching cubes to use the
> keyhole to join the inner and outer polygons?
> Part of the problem of this keyhole technique is the use of the words
> 'can be encoded'-- so while it's possible that other schemes could be
> used, this scheme is the only one suggested by the standard and is the
> one supported by Eclipse (and as far as I know, Eclipse's
> implementation is the one to match at the moment).
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