Hi,
This is somewhat OT, but am unable to contact the author of this program,
and can't find help elsewhere. The gshhstograss.c program imports all the
gshhs coastline data into a GRASS location
(http://www.ngdc.noaa.gov/mgg/shorelines/gshhs.html). However, there are
no instructions (AFAICS) on how this program needs to be compiled and
called. Has somebody successfully done this? I'd greatly appreciate any
tips.
Cheers,
--
Seb
Seb wrote:
This is somewhat OT, but am unable to contact the author of this
program, and can't find help elsewhere. The gshhstograss.c program
imports all the gshhs coastline data into a GRASS location
(http://www.ngdc.noaa.gov/mgg/shorelines/gshhs.html). However, there
are no instructions (AFAICS) on how this program needs to be compiled
and called. Has somebody successfully done this? I'd greatly
appreciate any tips.
I successfully imported them just a few weeks ago. Download the
shapefile versions and load them with v.in.ogr.
http://www.ngdc.noaa.gov/mgg/shorelines/data/gshhs/version1.5/shapefiles/
Hamish
On Fri, 16 Mar 2007 14:43:39 +1300,
Hamish <hamish_nospam@yahoo.com> wrote:
[...]
I successfully imported them just a few weeks ago. Download the
shapefile versions and load them with v.in.ogr.
Thanks, yes, I was also able to import them like that, but failed to
reproject a subset of the data into UTM. I used v.in.ogr to create a new
location with the geographic data, created another location with the
desired UTM and region settings, and then used v.proj to bring the
geographic vector to the new location. I got a very weird result
(http://members.shaw.ca/sluque/earctic.png). That's why I thought
something might be wrong with the shapefiles, so tried to use the
gshhstograss program instead.
--
Seb
NOAA GSHHS coastline data (see the v.in.gshhs module in GRASS 5.4)
Hamish:
> I successfully imported them just a few weeks ago. Download the
> shapefile versions and load them with v.in.ogr.
Seb:
Thanks, yes, I was also able to import them like that, but failed to
reproject a subset of the data into UTM. I used v.in.ogr to create a
new location with the geographic data, created another location with
the desired UTM and region settings, and then used v.proj to bring the
geographic vector to the new location. I got a very weird result
(http://members.shaw.ca/sluque/earctic.png). That's why I thought
[Alaska]
something might be wrong with the shapefiles, so tried to use the
gshhstograss program instead.
The UTM projection will only be valid within about 3-4 deg lon outside
of the zone. Data from the other side of the planet will head off into
all sorts of mathematical weirdness. In the lat/lon location use
v.in.region + v.overlay to crop out the region of interest and then
v.proj that into your UTM. Also UTM goes nuts near the poles, so
beware of anything north of 80-84 deg lat.
A much smarter man than myself explains:
http://lists.maptools.org/pipermail/proj/2005-August/001710.html
If you don't get an answer here, maybe ask on the PROJ.4 mailing list
what an appropriate PROJ-compatible projection for the arctic would be.
Hamish
A much smarter man than myself explains:
http://lists.maptools.org/pipermail/proj/2005-August/001710.htmlIf you don't get an answer here, maybe ask on the PROJ.4 mailing list
what an appropriate PROJ-compatible projection for the arctic would be.
For Antarctic data I normally use a Polar Sterographic projection, at least with GMT. It doesn't generate maps with rectangular borders though. Depending on what you are trying to do with the data, that or a suitable Equidistant or Equal Area projection will work OK.
I'm assuming GRASS will work OK, as I use Proj4 & PostGIS to manage the data for use with QGIS & GMT.
There is some info on this sort of thing at the NOAA NATICE website and at the British Antarctice Survey (BAS) SCAR/ADD sites. The Antarctic advice is just as useful at the other pole 
Googling for these acronyms will find the sites.
Cheers,
Brent Wood
Thanks Hamish and Brent, it seems my choice of UTM for this area is not
good. UTM had worked fine for me at a similar latitude further west (much
narrower in longitude though), but it seems things get ugly with wider
areas. I'll dig deeper.
Cheers,
--
Seb
