roberto caselli wrote: > Ok, row and col are known, but when I call > G_col_to_easting or G_row_to_northing, they return lat/lon coordinates. > So I don't know how to tell to these functions that I want UTM coordinates.
In that case, you'll need to obtain proj_info structures for both lat/lon and UTM. Then, you can use pj_do_transform() to perform the conversion. The usual way to create a proj_info structure is to pass Key_Value structures (which contain a set of key/value pairs) to pj_get_kv(). You can get the Key_Value structure for a GRASS location (i.e. your lat/lon location) from G_get_projinfo() and G_get_projunits(), but you'll need to construct the data for UTM yourself. One way to do that is to pass a WKT string to GPJ_wkt_to_grass(). Another is to construct the Key_Value structure manually with G_create_key_value() and G_set_key_value(). You can find everything involved in the v.proj code, except for constructing the Key_Value structure for the UTM location. -- Glynn Clements <[EMAIL PROTECTED]> _______________________________________________ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev