How about making d.barscale be approximately accurate in latlon near the bottom of the map and say so in the docs? Not ideal, but useable perhaps.
Michael On 7/2/07 11:56 PM, "Hamish" <[EMAIL PROTECTED]> wrote: > Michael Barton wrote: >> >> I know this has come up before, but I wanted to see if there might be >> a way to fix this now. > > see http://thread.gmane.org/gmane.comp.gis.grass.devel/2794/focus=2841 > >> I don't work much with latlon locations, but I know that a lot of >> people do. For large areas especially, it is one of the main ways to >> manage geospatial data. GRASS has pretty good tools for dealing with >> latlon and its idiosyncrasies. However, a peculiar gap is that the >> barscale tool won't work in latlon. Given that I'm told that there are >> GRASS libraries already in existence to deal with latlon to metric >> conversions, it seems odd that we can't put a scale on a latlon map. >> >> Is this actually a very difficult problem to solve, or just one that >> no one has yet gotten around to doing--I know that you all have sooo >> much free time on your hands ;-) > > > It's a problem of correctness, not a technical/time issue. > A horizontal plate carrée scale is only valid at a single lat, and > becomes more wrong as you zoom out or look up and down the map. See a > National Geographic map for a solution which has a series of scales in > the shape of a horn, where you choose a scale depending on the lat. > > > Glynn's suggestion in the above thread of changing the units to degrees > (or min,sec) could work. But then you could use d.grid for that. > > > note "d.barscale -n" will work in lat/lon as that doesn't need scale. > (north arrow only). Better: replace "d.barscale -n" with a symbol so you > can optionally draw the compass or fancy_compass under the "N" text > instead of the arrow-head. > > > Hamish __________________________________________ Michael Barton, Professor of Anthropology Director of Graduate Studies School of Human Evolution & Social Change Center for Social Dynamics & Complexity Arizona State University phone: 480-965-6213 fax: 480-965-7671 www: http://www.public.asu.edu/~cmbarton _______________________________________________ grass-dev mailing list [email protected] http://grass.itc.it/mailman/listinfo/grass-dev
