On Wed, Jan 5, 2011 at 21:49, klaatu <kla...@earthops.org> wrote: > On Wed, 5 Jan 2011, Tom Browder wrote: >> On Wed, Jan 5, 2011 at 17:03, klaatu <kla...@earthops.org> wrote: ... >>> The problem? Knowing the decimal degrees of latitude and longitude (x,y), >>> give a bearing and distance, and get a result in latitude/longitude (x,y). >> ... >>> For what it's worth, the best reference I could find for this was at: >>> http://williams.best.vwh.net/avform.htm#Triangle >> >> Doesn't the "Lat/lon given radial and distance" formulae on that site >> do what you want? > > In some cases, it gives a rough approximation. In other cases, it's > incredibly wrong. I think his math is good -- he's highly recommended -- > but his javascript implementation seems to have major problems in some > areas. Using input from google maps (lat/long) and giving bearing and > distance, I've gotten errors in results, which seem to be about 170 > degrees off. I've triple-checked and in those certain cases it is very > repeatably wrong. I suppose I should write to him, rather than to the > BRLCAD folks. I don't know that there is much use in BRLCAD for > computations of "great circle" problems, however large the universe or > however small the ruler, to reference a nice paper that used to be > distributed with the download.
Well I for one am interested--this is part of a ballistics routine I think. We can always go away if Sean kicks us off for being "off topic". (And note that BRL-CAD has the capability of using miles and km as units.) Can you post some examples? If you suspect it's his code, do you have the source? I haven't looked closely at the algorithms but I notice "bearings" used. Are the angles being entered and handled properly for the coordinate system? Regards, -Tom Thomas M. Browder, Jr. Niceville, Florida USA ------------------------------------------------------------------------------ Learn how Oracle Real Application Clusters (RAC) One Node allows customers to consolidate database storage, standardize their database environment, and, should the need arise, upgrade to a full multi-node Oracle RAC database without downtime or disruption http://p.sf.net/sfu/oracle-sfdevnl _______________________________________________ BRL-CAD Users mailing list brlcad-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/brlcad-users
