roberto caselli wrote: > Sorry for this silly question but I have a doubt now: Can an elevation > raster map have cells with different areas? I though that all cells in > a map had the same sizes...
All cells have the same dimensions measured in the location's coordinate system. However, for lat/lon data, each cell will have fixed dimensions in degrees, but it's physical area will vary with latitude. This is why G_area_of_cell_at_row() takes the row as an argument. For projected data, it returns a constant value based upon the region's resolution and the location's units (metres, feet, etc). For lat-lon data, the conversion takes into account the row's latitude and the location's ellipsoid. Also, note that G_begin_cell_area_calculations() must be called to initialise the conversion parameters prior to calling G_area_of_cell_at_row(). -- Glynn Clements <[EMAIL PROTECTED]> _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
