I've not before worked with SPCS in GRASS. I now need to define a new
location based on the SPCS for Nevada (East), and need to do this manually.
According to the startup page if I specify
$ grass65 /home/rshepard/grassdata/Nevada-SPCS/PERMANENT
will this make the above the CWD? If so, I assume that I immediately run
g.setproj and specify 'stp' as the projection name. What reference should I
use for the projection parameters?
Rich
On Sat, Jul 23, 2011 at 12:48 AM, Rich Shepard <rshepard@appl-ecosys.com> wrote:
I've not before worked with SPCS in GRASS. I now need to define a new
location based on the SPCS for Nevada (East), and need to do this manually.
According to the startup page if I specify$ grass65 /home/rshepard/grassdata/Nevada-SPCS/PERMANENT
will this make the above the CWD? If so, I assume that I immediately run
g.setproj and specify 'stp' as the projection name. What reference should I
use for the projection parameters?
I wouldn't do it this way.
Better use
- the wxGUI location manager from the startup screen
- or create the location from a GIS file (shape, geotiff, ..) with correct
metadata
- or create from the EPSG code
(is it this one?http://spatialreference.org/ref/epsg/3429/ )
Markus
Rich
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
On Sun, 24 Jul 2011, Markus Neteler wrote:
Better use
- the wxGUI location manager from the startup screen
Markus,
This is what I've tried. When I select STP as the projection I'm told that
I need to manually enter the definition.
- or create the location from a GIS file (shape, geotiff, ..) with correct
metadata
This, of course, would be too easy ... if such a map was available. None
of the data I've collected is in SPCS, unfortunately.
- or create from the EPSG code
(is it this one?http://spatialreference.org/ref/epsg/3429/ )
I'm not sure.
Searching the Web with Google lead me to a site that has the projection,
datum, and ellipsoid parameters for all SPCS zones. The above reference
uses US Feet as the measurement units while the current standard uses
Metres. (Snyder's book has conversion factors to adjust for NAD83 from
NAD27.)
Since SPCS is a derivative of the Transverse Mercator projection, the site
I found (which provides the data for free while selling projection
conversion software for Microsoft systems) tells me:
False northing: 8000000
False easting: 200000
Origin Latitude: 43.75
Origin Longitude: -115.583333333333
Parallel North: 0
Parallel South: 0
Scale Factor: 0.9999
It also has 0 as the parameters for NAD83 (apparently already adjusted)
and those for GRS89. I intend to use the above to define the location unless
I'm way off.
Thanks,
Rich
Rich Shepard wrote:
Since SPCS is a derivative of the Transverse Mercator projection, the site
I found (which provides the data for free while selling projection
conversion software for Microsoft systems) tells me:False northing: 8000000
False easting: 200000
Origin Latitude: 43.75
Origin Longitude: -115.583333333333
Parallel North: 0
Parallel South: 0
Scale Factor: 0.9999It also has 0 as the parameters for NAD83 (apparently already adjusted)
and those for GRS89. I intend to use the above to define the location unless
I'm way off.
PROJ's EPSG file says:
# NAD83(HARN) / Nevada East (ft US)
<3429>
+proj=tmerc
+lat_0=34.75
+lon_0=-115.5833333333333
+k=0.9999
+x_0=200000.00001016
+y_0=8000000.000010163
+ellps=GRS80
+units=us-ft
Which is identical except for lat_0 (34.75 vs 43.75), which might be a
transcription error.
According to:
http://www.ngs.noaa.gov/PUBS_LIB/ManualNOSNGS5.pdf
"NOAA Manual NOS NGS 5 - State Plane Coordinate System of 1983"
34.75° (34°45') is correct for SPCS 2701 (Nevada East); page 68 (PDF
page 78) says:
Grid Origin
Central Meridian Longitude Easting
State/Zone/Code Projection and Scale Factor Latitude Northing
Nevada NV
East E 2701 T.M. 115 35 115 35 20,000.
1:10,000 34 45 8,000,000.
--
Glynn Clements <glynn@gclements.plus.com>
On Sun, 24 Jul 2011, Glynn Clements wrote:
PROJ's EPSG file says:
# NAD83(HARN) / Nevada East (ft US)
<3429>
+proj=tmerc
+lat_0=34.75
+lon_0=-115.5833333333333
+k=0.9999
+x_0=200000.00001016
+y_0=8000000.000010163
+ellps=GRS80
+units=us-ftWhich is identical except for lat_0 (34.75 vs 43.75), which might be a
transcription error.
Oops! I did transpose the degrees.
A couple of decades ago when I worked in SPCS I did use US Feet. Should I
do so now, too, rather than metres?
Thanks, Glynn,
Rich
On Sun, Jul 24, 2011 at 2:57 PM, Rich Shepard <rshepard@appl-ecosys.com> wrote:
On Sun, 24 Jul 2011, Markus Neteler wrote:
Better use
- the wxGUI location manager from the startup screenMarkus,
This is what I've tried. When I select STP as the projection I'm told that
I need to manually enter the definition.- or create the location from a GIS file (shape, geotiff, ..) with correct
metadataThis, of course, would be too easy ... if such a map was available. None
of the data I've collected is in SPCS, unfortunately.- or create from the EPSG code
(is it this one?http://spatialreference.org/ref/epsg/3429/ )I'm not sure.
See also
http://spatialreference.org/ref/epsg/32107/
(or check on http://epsg-registry.org/ )
Markus
Rich Shepard wrote:
A couple of decades ago when I worked in SPCS I did use US Feet. Should I
do so now, too, rather than metres?
As Markus mentions, EPSG:32107 is identical to EPSG:3429 except that
the units are metres rather than US feet.
Whichever you choose, source data could use either (or both), so be
careful to check.
--
Glynn Clements <glynn@gclements.plus.com>
On Mon, 25 Jul 2011, Glynn Clements wrote:
As Markus mentions, EPSG:32107 is identical to EPSG:3429 except that
the units are metres rather than US feet.
Thank you.
Whichever you choose, source data could use either (or both), so be
careful to check.
My source data are in neither. Some agencies use Albers Equal Area), other
agencies use UTM (there's a mix of NAD27 and NAD83), other sources use
Lon/Lat. _I'm_ reprojecting everything to SPCS as the most appropriate for
large scale terrain and hydrological modeling and analyses.
Rich