On 21/09/16 09:35, Nikos Alexandris wrote:
Rich Shepard wrote:

The LiDAR source location has x- and y-resolution of 3 feet
(international) and several thousand cells east-west and north-south.
g.region -p for this location displays:

projection: 99 (unnamed)
zone:       0
datum:      ** unknown (default: WGS84) **
ellipsoid:  grs80
north:      1286590.24500872
south:      1240510.24500872
west:       634966.76150938
east:       664972.76150938
nsres:      3
ewres:      3
rows:       15360
cols:       10002
cells:      153630720

   When in the project location g.region -p produces:

projection: 99 (NAD_1983_HARN_StatePlane_Oregon_North_FIPS_3601_Feet_Intl)
zone:       0
datum:      nad83harn
ellipsoid:  grs80
north:      588219.90693215
south:      536993.58817534
west:       7524575.13218961
east:       7561596.20977101
nsres:      2561.31593784
ewres:      1851.05387907
rows:       20
cols:       20
cells:      400

   I want to understand why the nsres is now 2561+ feet, the ewres now
1851+
feet, and the numbers of rows and columns has decreased so drastically.

Looking forward to learning,

Helmut Kudrnovsky:

If it is about raster reprojection, there are hints in the r.proj manual
about region settings before applying r.proj.

E.g.

A simple way to do this is to check the projected bounds of the input map in
the current location's projection using the -p flag. The -g flag reports the
same thing, but in a form which can be directly cut and pasted into a
g.region command.

Some observation: `-g` prints out in shell style, suitable for
`eval`uating.  The `eval` utility, for example, constructs a
command, from the given arguments (here, the ouput of `g.region -g`)
which is then executed by the shell.  See for example
https://grasswiki.osgeo.org/wiki/Shell_scripting#Using_output_from_GRASS_modules_in_the_script.

A ready to copy-n-paste form is obtained via `-f` (this is a recent
addition by Moritz during the code sprint in Bonn).

Maybe the `-f` flag would be a useful addition to `r.proj` as well.

AFAIR, the -g flag in r.proj already outputs flat format.

Moritz
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