Michael Misun wrote: > i know, that in grass4 was a module called v.plant which fills in > points on a line in a specified space but i doesn't work here in my > grass6.2.3
it seems available in GRASS 5.4 too: http://grass.ibiblio.org/gdp/html_grass5/html/v.plant.html >From that help page: "Design of v.plant v.plant has been implemented as a Bourne shell script. The basic procedure is as follows: 1. Write out the existing map in the dig_ascii format; 2. Use an included awk script to process each vector segment in turn, moving from point to point along the segment. If a span between two adjacent points is greater than the specified threshold (in map units) extra points are inserted collinearly. 3. The modified dig_ascii file is re-imported, overwriting the original file." the main difference between GRASS 5 & 6's ascii output format is the order of the columns (x y in GRASS 6, not y x as in GRASS 5). so with that adjustment (and probably a few other minor tweaks) the script could probably be used in GRASS 6. GRASS 4/5 vector modules using the C api need considerable rewrite to work with GRASS 6 as the GRASS 6 vector engine is a all new. But you can use v.split, v.segment, or v.lrs.* in GRASS 6 to do the same thing as v.plant. for GRASS 5/6 porting list see: http://grass.gdf-hannover.de/wiki/GRASS_Module_Porting_List#Vector_modules > above all i work in a location for mars not for the earth That should not be a problem. If your lat/lon projection definition defines 'a' and 'es' parameters (or 'a' + defined as a sphere), then G_geodesic_distance() will use those values in the distance calculation. It only defaults to Earth values if those are empty. see G_get_ellipsoid_parameters() in lib/gis/get_ellipse.c which is called by G_begin_distance_calculations() (lib/gis/distance.c). G_distance() then calls G_geodesic_distance() if the projection is lat/lon. [see also lib/gis/geodist.c and lib/gis/geodesic.c] e.g. d.measure with an xmon should return the correct great circle distance. (I have no idea about the distance measurement tool in the GUIs) Again, be careful with new vector modules. Some may be simplisticly doing their own sqrt(a^2 + b^2) calucations instead of using G_distance(). Luckily the results should be so badly wrong for lat/lon locations that you will quickly notice the error. Post any requests for specific module updates to the wish/bug tracker. Hamish ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
