Hello, thanks to Paul Kelly and Frank Warmerdam (http://proj.maptools.org/), the below mentioned issue is solved; when I simply added: "nadgrids:@null" to the projection definition file (PROJ_INFO), then I obtained correct results. Cited from Frank's mail:
"The trick to having cs2cs (or anything based on pj_transform()) apply no change to coordinates when going from the sphere to WGS84 is to add [EMAIL PROTECTED] to your gnomonic (or spherical projection) definition." Milan Milan Salek wrote: > Hello, > > I am referring to the reprojection problem of GRASS6.x described here: > http://www.intevation.de/rt/webrt?display=History&serial_num=3630 > > To sum up, the GRASS version 5.3+ (i.e., the current version 6.2, too; I'v not > tested CVS version) incorrectly reprojects the maps between coordinate system > using gnomonic projection (using only sphere as a reference body) and any > other > coordinate system with projection using ellipsoid. There is obvious erroneous > north-south shift of approx 0.19 degree (at 50 deg latitude), very likely due > to > the different reference body (and mayby because of the mix of of > geodetic/geometric latitude - ?). > > The system proj (http://proj.maptools.org/) works OK, there is not a problem. > > The old [vr].proj in GRASS 5.0.3 is reprojecting perfectly, without any shift, > obviously handling the reference body correctly. I think that there could be > some possibility to fix the problem if this old version works OK. Maybe the > problem could have been connected with the introduction of the datum > transformation function in grass5.3 (http://grass.itc.it/devel/roadmap.php). > > I would like to ask if there is a possibility to fix the shortcoming. > As a workaround, I still have to maintain the old version of GRASS 5.0.3 at > one > computer just for the reprojections using gnomonic projection. For some > reprojection tasks I have available external programs, but the correction of > the > above mentioned error would be very helpful. If the correction of the error > (or > feature?) :o) is not planned in the future, let me know, too, please. > > BTW, is anywhere a repository of old GRASS 5.0.3 for cygwin? I'v found only > GRASS 5.4. > > Thanks in advance for any response. > > Milan Salek > -- ___________ \ o o / Milan Salek \ ^ / Regionalni predpovedni pracoviste \ ~ / Regional Forecasting Office Brno ( ( ) ) Czech Hydrometeorological Institute ( ( . ) ) Kroftova 43, 616 67 Brno, Czech Republic ( ( . ) ) (____________) ) tel.: +420-541 421 072 //// fax : +420-541 421 018 //// E-mail: [EMAIL PROTECTED] cell phone: +420-724 185 618 http://www.chmi.cz Ceska meteor. spolecnost / Czech Meteorological Society: http://www.chmi.cz/poboc/BR/metspol/metspol.html ------------------------------------------------------------ _______________________________________________ grassuser mailing list [email protected] http://grass.itc.it/mailman/listinfo/grassuser
