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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Hi Ugo, Yes. Surface rendering is based on filling in the quadrangles (Gridded) or triangles (Irregular) of the Field's topology. When the display logic detects that any points have been removed, either because of missing values or SelectRange, then the topology is invalid so it falls back on point rendering, which does not require topology. Currently, the only work-around is for the application to reconstruct a new topology, either using the IrregularSet constructors (slow for lots of points) or explicitly using DelaunayCustom if the application has some information about the new topology. Note that iso-surfaces and iso-lines work a bit differently, and will evaluate the validity of each topology cell. This can be misleading, since there may be many valid points but no valid cells (i.e., each cell may include at least one invalid point). In this sense falling back on point rednering is good, since it shows precisely which samples are valid. We could add an option for surface rendering [i.e., for Fields of the form ((x, y) -> z)] to render those cells that have all points valid [similar to the way iso-surface works now]. I've been veryy busy lately but when I get a breather I will try to do this. Cheers, Bill p.s., NOTE that my email address has changed to hibbard@xxxxxxxxxxxxxxxxx The old email server is a VAX with fatal Y2K flaws. ---------------------------------------------------------- Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI 53706 hibbard@xxxxxxxxxxxxxxxxx 608-263-4427 fax: 608-263-6738 http://www.ssec.wisc.edu/~billh/vis.html
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