Le samedi 11 août 2007 à 17:59 +1000, Richard Chirgwin a écrit : > Vincent, > > Vincent BAIN wrote: > > Hello Richard, > > don't know if it can help, but for me it works, from conformal conic > > Lambert to rgf93 (the official geographic coord system in France, > > compliant with wgs84). > > > > Could you send us the proj information from each of your locations, and > > make sure they correspond to your project ? > > > The XY location was defined using EPSG code 20356 (Australia from > Geosciences). It shows UTM projection, zone 56, AGD84 datum, and > ellipsoid data. > > The LCC location was "self-defined" during import - that is, I created a > new location during import. The project info it created is below: > g.region -p > projection: 99 (Lambert Conformal Conic) > zone: 0 > datum: towgs84=-134,-48,149,-0,-0,-0,0 > ellipsoid: a=6378160 es=0.006694541854587638 > north: 6784163.1212489 > south: 3123142.28999373 > west: 2961606.17926652 > east: 6874125.97609581 > nsres: 183051.04156276 > ewres: 195625.98984146 > rows: 20 > cols: 20 > cells: 400 > > > > The problem is that I don't know what EPSG code the creator of the > mapset I'm trying to import was using!
You mean : you have data in XY coordinate, but you don't know what coord system it's linked to ? then it's a serious problem :-) maybe you can try with a "standard" lambert in use in Australia > > > I advise you to define the coordinate systems from epsg codes, the best > > way -- i think -- to avoid problems defining the right ellipsoïd, datum, > > and so on... > > > > And be cautious: the coordinates read from the display are decimal... > > > <whacks forehead> I suspect you're telling me I should be using > degree-minute-second format in my transformation? I just meant sometimes we careless try to check the transformation by comparing decimal values of coordinates to deg,min,sec values... (it's the kind of mistake I do every day !) > > Thanks, I will go back and look at how I can get the projections lined > up ... I might try defining a standard Australian LCC and see if the > import works; then from a standard location to a standard location might > well be easier. good luck > > Richard > > Bon courage, > > Vincent > > > > Le samedi 11 août 2007 à 09:32 +1000, Richard Chirgwin a écrit : > > > >> It's me again ... I suspect I must be stupider than most Grass users > >> because I seem to be hitting the list with questions so often! > >> > >> I have my own maps which are in lat-long format, using Australian > >> boundaries. > >> > >> I need to analyse some points relative to some centroids supplied in > >> MapInfo format. They import fine, but they're in Lambert Conformal > >> Conical projection. > >> > >> Without being long-winded, my attempts to reproject the LCC location > >> into a lat-long UTM using WGS84 keep failing - the utilities work but > >> the result isn't right. > >> > >> Is there something about LCC projections that make them hard to reproject? > >> > >> Richard > >> > >> _______________________________________________ > >> grassuser mailing list > >> [email protected] > >> http://grass.itc.it/mailman/listinfo/grassuser > >> > >> > > > > > > _______________________________________________ > grassuser mailing list > [email protected] > http://grass.itc.it/mailman/listinfo/grassuser > _______________________________________________ grassuser mailing list [email protected] http://grass.itc.it/mailman/listinfo/grassuser
