Re: inverse mapproject -C confusion
"Altekruse, Jason [FWLA]" <[email protected]>
| Newsgroups | gmane.comp.gis.gmt.user |
|---|---|
| Message-ID | <[email protected]> |
Joaquim - thanks for the explanation. I tried transverse Mercator (-Jt) and it generated a grid quite similar to azimuth equidistance (-Je), and Albers (-Jb). Out of curiosity, I arbitrarily picked a few more projections to try out. As for the Merc projection (-Jm), I had to exclude the -C option and set west and south in the range to the site coordinates (target grid center) for Cylind. Eqdist (-Jq) and UTM(-Ju), but not Az Eqdist (-Je), transverse Merc (-Jt), or Albers (-Jb). Still not sure I quite understand the why, but its good enough.
Eduardo - Ah, thank you. I thought something like this was possible but couldn't remember how. I tweaked your suggestion - I used each point from a single east-west line as the center of a north-south line to fill in the grid:
$ project -C-122/38 -A90 -L-120/120 -G10 -Q | \
awk '{system("project -A0 -L-120/120 -G10 -Q -C"$1"/"$2);}' > grid_ll.xy
Cheers,
Jason
-----Original Message-----
From: World-Wide GMT Usage and Help Mailing List [mailto:[email protected]] On Behalf Of Eduardo A. Suárez
Sent: Thursday, January 16, 2014 1:11 AM
To: [email protected]
Subject: Re: [GMT-HELP] inverse mapproject -C confusion
Quoting "Altekruse, Jason [FWLA]" <[email protected]>:
> I'm trying to create a geographic grid covering a 100-km radius
> circle centered at -122,38 with 1-km spacing. Is there a better way
> to generate a geographic grid (data table) with arbitrary grid
> spacing specified in km?
why don't you use project to do that?
I think that a loop with something like
project -C-122/38 -A0 -L0/100 -G1 -Q
project -C-122/38 -A180 -L0/100 -G1 -Q
shift -C coordinates 1 Km to the east/west
can create your grid.
Eduardo.-
--
Eduardo A. Suarez
Facultad de Ciencias Astronómicas y Geofísicas - UNLP
FCAG: (0221)-4236593 int. 172/Cel: (0221)-15-4557542/Casa: (0221)-4526589
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