[GRASS-user] Re: visualising high latitude regions

GRASS GRASS user
1

Yep, GRASS can do it that way, I suggest you look at GMT (http://gmt.soest.hawaii.edu) for quality map production & cartography...

OGR now supports GMT vector (multiline) output, so it is easy to convert data to GMT format for plotting.

Cheers

   Brent Wood

Brent Wood
DBA/GIS consultant
NIWA, Wellington
New Zealand

Wouter <wouter.buytaert@scarlet.be> 12/17/08 7:23 AM >>>

Answer to my own question:

- have your data in UTM
- make a grid in a latlong location with v.mkgrid
- reproject the grid to your UTM location with v.proj
- visualise the grid over your data of interest
- add labels with the latlong coordinates

cheers
wouter

On Tue, 16 Dec 2008, Wouter wrote:

Date: Tue, 16 Dec 2008 14:46:47 -0300 (CLST)
From: Wouter <wouter.buytaert@scarlet.be>
To: grass-user@lists.osgeo.org
Subject: visualising high latitude regions

Hi all,

is there a way in GRASS to draw latlong projection data with a non-straight
coordinate grid? Something like this:
<http://www.lib.utexas.edu/maps/americas/chile.gif&gt;

Particularly for high latitudes such as Patagonia, a straight grid gives a
lot of distortion.

Any suggestions to do this in other software are welcome. I even don't know
if ArcGIS does this.

thanks
wouter

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2

Wouter wrote:

is there a way in GRASS to draw latlong projection data with a
non-straight coordinate grid? Something like this:
<http://www.lib.utexas.edu/maps/americas/chile.gif&gt;

Particularly for high latitudes such as Patagonia, a straight grid
gives a lot of distortion.

....

Answer to my own question:

- have your data in UTM
- make a grid in a latlong location with v.mkgrid
- reproject the grid to your UTM location with v.proj
- visualise the grid over your data of interest
- add labels with the latlong coordinates

which is nice if you want to output a shapefile to use as an overlay
with e.g. QGIS, but there is a much much easier way...

use 'd.grid -g size=0:30' or 'd.grid -w size=5' to draw eg 30min or 5deg
lat/lon grid over your current map projection display.
d.grid has a number of nice options.

also in ps.map there is the "geogrid" command which does something similar.

Brent wrote:

Yep, GRASS can do it that way, I suggest you look at GMT
(http://gmt.soest.hawaii.edu) for quality map production & cartography...

& ps.map :slight_smile:

OGR now supports GMT vector (multiline) output, so it is easy to
convert data to GMT format for plotting.

OGR tip added to the GRASS/GMT wiki page:
  http://grass.osgeo.org/wiki/GRASS_and_GMT

(that page, and the [r|v].[in|out].gmt scripts really need a cleanup)

Hamish

3

Hamish:

also in ps.map there is the "geogrid" command which does something similar.

example here:
http://grass.osgeo.org/wiki/Ps.map_scripts#Creating_a_fancy_North_Arrow

Hamish