[vtkusers] Re: [vtk-developers] contour lines and scalar color plot issues with vtkUnstructuredGrid

[Burlen]

Wanted to thank you all for the input and comments. Since vtkAppendFilter 
doesn't stitch the datasets that are appended(wouldn't it be nice if it 
did?), I gave up on that avenue, and instead construct a dataset using the 
Delaunay triangulation filter as shown on 143 of the user guide. The feedback 
I got here was a big help.

thanks again
Burlen

On Wednesday 15 February 2006 10:59 am, Randall Hand wrote:
> On 2/15/06, Burlen <burlen at apollo.sr.unh.edu> wrote:
> > It seems to me that the problem of open contours might be caused by the
> > algorithm(s) used with unstructuredGrids built with the append filter.
> > Could
> > it have somehting to do with the fact that the boxes in my case are
> > appended
> > in a "willy nilly" order? adjacent boxes aren't necessarily appended one
> > after the other.
>
> I think this is the cause of your problem.  The vtkAppendFilter does not
> "stitch" neighboring datasets along their boundaries, it keeps each dataset
> as an individual piece.  So when you extract an isosurface from the
> combined dataset, there is no connectivity along those inter-dataset
> boundaries, leading to the "discontinuity" along the edges.  I've run into
> the same issue here doing similiar things (reading a multi-block Plot3d
> file & using AppendDataset to only have 1 vtkDataSet to pass around).
>
> How to fix this?  I haven't the slightest, short of writing custom code to
> replace vtkAppendDataset and do the stitching.  You may be able to Resample
> the Data into a rectilinear form (use the ProbeFilter with an ImageData
> input), and then get the Isosurface you want, but you'll have to live with
> the resolution tradeoffs.  It'll also be sloooooow....
>
>
> --
> Randall Hand
> Visualization Scientist,
> ERDC-MSRC Vicksburg, MS
> Homepage: http://www.yeraze.com

-- 

Burlen Loring
Space Science Center
Institute for the Study of Earth, Oceans, and Space
University of New Hampshire
39 College Road, Durham, NH 03824
Phone: 603-862-1140