Hamish: > > I have used v.to.points to create a series of points that fall along a > > line. Now I want to upload to a DB column in the points map the > > instantaneous heading of the original line at that sample point.
Markus: > This functionality might be added to v.to.db - perhaps > using Vect_get_node_line_angle(): > http://download.osgeo.org/grass/grass6_progman/level__two_8c.html#a16 hmmm. at a node there are two lines, the fn wants to know which one. I have a point somewhere along the line (between two vertices) and want to #1 find the polyline, #2 extract the current linear feature (between two nearest connected vertices), and #3 calc the angle of that line. I see now the corner case of if the point falls exactly on a vertex or a node you will have to average to angles of the lines on either side. I don't think v.to.db could help other than the overall bearing from the polyline's start node to end node. Remember a single line cat can only hold a single value. 'v.distance upload=to_angle' might be something... Hamish _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
