[GRASSLIST:9566] Global topography

GRASS GRASS user
1

Hi all,

I'm trying to georeference the global topography data here:

ftp://topex.ucsd.edu/pub/global_topo_2min

WIth more info here:
http://topex.ucsd.edu/WWW_html/mar_topo.html

It comes with hdr and ers files (attached) but GRASS opens the img
data as unprojected.

I've tried setting the projection and datum manually and then
importing but I'm just getting myself horribly confused.

I managed to find a file online that defined the MRWORLD projection as:
MRWORLD:PROJCS["MRWORLD",PROJECTION["Mercator_1SP"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",0],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",20000000]]

I also tried manually setting the cell header as per the conversions
in the GRASSLIST post here:
http://lists.directionsmag.com/discussion/read.php?f=16&i=1388&loc=0&t=1388

Can anyone help me?

Alternatively, if there is a global topography (including sea floor)
dataset which is more easily included with correct projection and
datum then feel free to point me to that.

Much thanks,
Joel

(attachments)

topo_8.2.ers (884 Bytes)

2

Here is the HDR fiel I forgot to attach.

On 12/19/05, Joel Peter William Pitt <joel.pitt@gmail.com> wrote:

Hi all,

I'm trying to georeference the global topography data here:

ftp://topex.ucsd.edu/pub/global_topo_2min

WIth more info here:
http://topex.ucsd.edu/WWW_html/mar_topo.html

It comes with hdr and ers files (attached) but GRASS opens the img
data as unprojected.

I've tried setting the projection and datum manually and then
importing but I'm just getting myself horribly confused.

I managed to find a file online that defined the MRWORLD projection as:
MRWORLD:PROJCS["MRWORLD",PROJECTION["Mercator_1SP"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",0],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",20000000]]

I also tried manually setting the cell header as per the conversions
in the GRASSLIST post here:
http://lists.directionsmag.com/discussion/read.php?f=16&i=1388&loc=0&t=1388

Can anyone help me?

Alternatively, if there is a global topography (including sea floor)
dataset which is more easily included with correct projection and
datum then feel free to point me to that.

Much thanks,
Joel

(attachments)

topo_8.2.hdr (228 Bytes)

3

I'm trying to georeference the global topography data here:

ftp://topex.ucsd.edu/pub/global_topo_2min

..

Alternatively, if there is a global topography (including sea floor)
dataset which is more easily included with correct projection and
datum then feel free to point me to that.

With a little work you can probably get that data loaded, but for
something with detailed instructions try the ETOPO2 dataset. See the
article in GRASSNews vol 1.
  http://grass.ibiblio.org/newsletter/index.php

ETOPO2 includes the Smith & Sandwell satellite altimeter derived
bathymetry.

Hamish

4

You can also try SRTM30_PLUS.http://topex.ucsd.edu/WWW_html/srtm30_plus.html

Also check out this thread from the mailing list about importing these
data into GRASS:

http://grass.itc.it/pipermail/grassuser/2005-August/030000.html

best regards

Carlos

On 12/19/05, Hamish <hamish_nospam@yahoo.com> wrote:

> I'm trying to georeference the global topography data here:
>
> ftp://topex.ucsd.edu/pub/global_topo_2min
..
> Alternatively, if there is a global topography (including sea floor)
> dataset which is more easily included with correct projection and
> datum then feel free to point me to that.

With a little work you can probably get that data loaded, but for
something with detailed instructions try the ETOPO2 dataset. See the
article in GRASSNews vol 1.
  http://grass.ibiblio.org/newsletter/index.php

ETOPO2 includes the Smith & Sandwell satellite altimeter derived
bathymetry.

Hamish

--
+-----------------------------------------------------------+
              Carlos Henrique Grohmann - Guano
  Geologist M.Sc - Doctorate Student at IGc-USP - Brazil
Linux User #89721 - carlos dot grohmann at gmail dot com
+-----------------------------------------------------------+
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