On page 222 (page 232 in Adobe PDF) of the ver 6.5 Users Guide it says about the Distance parameter in the TIN thematic map creation: "The Distance value controls the output. For non-zero distance values, only edges or triangles contained within a sphere centered at mesh vertices are output. This is useful to constrain the triangulated irregular network to a specified distance; otherwise, the triangulation will cross concave regions." Anyone know what that second sentence means? I assume that the "sphere" has a radius of "Distance," but what exactly is "output"? Is it triangles, or triangle edges, or colored cells? Or is "or" supposed to be "of"? Is Distance really in miles units? Using the US_rain tutorial data set, I fed the TIN gridder the data for Jun, with no clipping table. The wizard set the default distance to 47.75. Use that and the Gulf of Mexico gets filled in from Brownsville, TX to Key West FL. Use 30 mi, and the cells in the triangle Brownsville-New Orleans-Key West are clear. Use 15 mi, and the gulf is now completely clear, but so is a large part of the southwest. So I see what it is supposed to control, but I don't see how the distance relates exactly to which triangles are included and which are left out. Does anyone know how to interpret this documentation? (Obviously the programmer didn't write it!) -- - Bill Thoen ------------------------------------------------------------ GISnet, 1401 Walnut St., Suite C, Boulder, CO 80302 tel: 303-786-9961, fax: 303-443-4856 mailto:[EMAIL PROTECTED], http://www.ctmap.com/gisnet ------------------------------------------------------------ _______________________________________________________________________ List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, send e-mail to [EMAIL PROTECTED] and put "unsubscribe MapInfo-L" in the message body.
