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<TITLE>Re: [Paraview] netCDF reader</TITLE>
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<FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>The netCDF reader in ParaView implements the COARDS convention, which is a subset of the CF convention. To the best of my knowledge, both conventions define the spherical coordinates in the same way. So if you have a netCDF file containing the CF convention for latitude and longitude, then the ParaView netCDF reader should understand that.<BR>
<BR>
That said, I see that the netCDF reader will only actually create spherical coordinates for 3D grids. I am not sure I remember the logic behind that, but I think it was that in general it is usually better to visualize a map surface as a 2D projection to prevent occlusion and that it is ambiguous what the height of the surface should be. That said, it is easy to implement spherical coordinates to 2D grids. I just checked in a change that creates a sphere at radius 1.<BR>
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The idea of the netCDF reader outputting a vtkPolyData is unworkable. Many netCDF files contain 3D grids, and vtkPolyData is incapable of representing those. It could always output a vtkUnstructuredGrid, but this is a highly inefficient format for storing the structured arrays stored in netCDF COARDS files. It is conceivable that the netCDF reader could always output a vtkStructuredGrid. But that means that non-COARDS files are forced to also output vtkStructuredGrid and they loose the features for using vtkImageData. I know there are issues with the VTK/ParaView pipeline when you change the output of the reader when you change the dimensions. But there are also similar problems when you change the extent and dimensionality anyway, so I don’t know how much help such a change would make.<BR>
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-Ken<BR>
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On 1/12/10 5:52 PM, "Brockmann Patrick" <<a href="Patrick.Brockmann@cea.fr">Patrick.Brockmann@cea.fr</a>> wrote:<BR>
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</SPAN></FONT><BLOCKQUOTE><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Hi all,<BR>
<BR>
Testing the netCDF reader with "spherical coordinates" set, I get<BR>
a vtkStructured Grid incomplete. There is no circular topology.<BR>
I was expecting a complete sphere where points from first column would be<BR>
connected to points from last column in the vtkStructuredGrid created.<BR>
<BR>
Is there a way to do this from an existing filter or from<BR>
the python programmable filter ?<BR>
Or better could the netCDF reader be corrected<BR>
(VTK/IO/vtkNetCDFCOARDSReader.cxx) ?<BR>
<BR>
By the past, I have installed and used the external plugin CSCSnetCDF<BR>
reader<BR>
from John Biddiscombe of the Swiss National Supercomputing Centre.<BR>
I was quite happy with it.<BR>
Today, I discover that paraview binairies are distributed with the<BR>
netCDFCOARDS reader<BR>
with some features I don't like. For example, that fact that the vtk<BR>
structure created<BR>
are different following the netCDF grid topology (regular spacing or<BR>
not, spherical coordinates or not).<BR>
<BR>
I think it would be attractive for all the General Circulation Model<BR>
(GCM)/ /community<BR>
to provide a netCDF reader, closer to the CF (Climate and Forecast<BR>
netCDF convention) widely adopted.<BR>
This reader would create for example a same vtkPolydata structure<BR>
whatever the netCDF grid read<BR>
as in the vtk application described from<BR>
<a href="http://www.prism.enes.org/Publications/Reports/Report19.pdf">http://www.prism.enes.org/Publications/Reports/Report19.pdf</a><BR>
<BR>
Is there any interest to develop this netCDFCF reader among offcial dev<BR>
team ?<BR>
<BR>
Thanks<BR>
Patrick<BR>
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**** Kenneth Moreland<BR>
*** Sandia National Laboratories<BR>
*********** <BR>
*** *** *** email: <a href="kmorel@sandia.gov">kmorel@sandia.gov</a><BR>
** *** ** phone: (505) 844-8919<BR>
*** web: <a href="http://www.cs.unm.edu/~kmorel">http://www.cs.unm.edu/~kmorel</a><BR>
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