Re: scale error for each pixel
Moritz Lennert <[email protected]>
| Newsgroups | gmane.comp.gis.grass.user |
|---|---|
| Message-ID | <[email protected]> |
On 20/11/17 21:20, Ken Mankoff wrote: > Dear Helmut, > > On 2017-11-02 at 07:17, Helmut Kudrnovsky <[email protected]> wrote: >> Ken Mankoff wrote >>> Does GRASS (or GDAL?, proj4?) have a function (or addon) to provide the >>> scale error for a given cell? >> >> AFAIR there is now an area function in r.mapcalc in GRASS trunk to calculate >> the pixel area. > > There is. I've just built GRASS 7.5. But the area() function just returns nsres*ewres for each cell, it does not consider projection errors. You could run area() both in your projected location and in a lat-long location (preferably using a similar datum), although you would have to be careful in the definition of the resolution in each location. Comparing the output should give you a notion of projection error. For visualization you might want to try the Indicatrix mapper Plugin in QGIS... Moritz _______________________________________________ grass-user mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-user