[Gdal-dev] Alabama geotiff tiles are showing up in Virginia
withinmapserver
Ed McNierney
ed at topozone.com
Thu Feb 8 21:27:31 EST 2007
John -
I think I answered that question below. Remember that an "EPSG code"
really means "a projection definition with the specified ID number
installed in the text file named epsg on your computer". If the
projection definition I described below for the 102629 projection is not
already present in your epsg file (a text file that's part of your PROJ
installation) you can edit that file by inserting the lines I provided
below. The 1xxxxx series EPSG codes are ESRI-defined extensions to the
standard EPSG set, so they are often not found in user installations
that don't use ESRI software.
- Ed
Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA 01863
Phone: +1 (978) 251-4242
Fax: +1 (978) 251-1396
ed at topozone.com
________________________________
From: John Mitchell [mailto:mitchelljj98 at gmail.com]
Sent: Thursday, February 08, 2007 8:52 PM
To: Ed McNierney
Cc: MAPSERVER-USERS at lists.umn.edu; Gdal-Dev; mitchelljj98 at gmail.com
Subject: Re: [Gdal-dev] Alabama geotiff tiles are showing up in Virginia
withinmapserver
Ed,
Thanks for the information.
What should I use for the EPSG code when using mapserver or gdalwarp?
John
On 2/8/07, Ed McNierney <ed at topozone.com> wrote:
John -
Alabama East SPCS as EPSG:26929 is in units of meters, but your
GeoTIFF seems to think it's in feet. This will cause the reprojection
to move the file 3 times further from the CS origin than you think.
It seems like you have a "hybrid" GeoTIFF with one projection
definition and a different EPSG code.
The ESRI-defined code of 102629 is an Alabama East NAD83 Feet
projection. The definition is:
# NAD 1983 StatePlane Alabama East FIPS 0101 Feet
<102629> +proj=tmerc +lat_0=30.5 +lon_0=-85.83333333333333
+k=0.999960 +x_0=200000 +y_0=0 +ellps=GRS80 +datum=NAD83
+to_meter=0.3048006096012192 no_defs <>
Which is identical to the 26929 definition except for the
"to_meter" parameter.
- Ed
Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA 01863
Phone:
<chrome://skype_ff_toolbar_win/content/cb_transparent_l.gif>
<chrome://skype_ff_toolbar_win/content/famfamfam/us.gif>
<chrome://skype_ff_toolbar_win/content/space.gif>
<chrome://skype_ff_toolbar_win/content/space.gif>
<chrome://skype_ff_toolbar_win/content/space.gif>
<chrome://skype_ff_toolbar_win/content/space.gif> +1 (978) 251-4242
<chrome://skype_ff_toolbar_win/content/cb_transparent_r.gif>
Fax: +1 (978) 251-1396
ed at topozone.com
________________________________
From: gdal-dev-bounces at lists.maptools.org
[mailto:gdal-dev-bounces at lists.maptools.org] On Behalf Of John Mitchell
Sent: Thursday, February 08, 2007 6:38 PM
To: MAPSERVER-USERS at lists.umn.edu; Gdal-Dev
Cc: mitchelljj98 at gmail.com
Subject: [Gdal-dev] Alabama geotiff tiles are showing up in
Virginia withinmapserver
Hi,
I have Alabama geotiff tiles which are showing up in Virginia
within mapserver. If you look at the original gdalinfo against one of
the tiles you will see that the corner coordinates are within Alabama,
but within MapServer if you do on the fly projection(EPSG:26929 to
EPSG:4326) it instead shows up within the state of Virginia. I also
used gdalwarp to change the projection from EPSG:26929 to EPSG:4326 and
then displayed within mapserver without having to reproject on the fly
and it also shows up within Virginia. Note: when running gdalinfo on the
gdalwarp file which was reprojected to EPSG:4326 it also has the
coordinates within the state of Virginia.
Below are the gdalinfo dumps first the original file and then
the file that was converted from EPSG:26929 to EPSG:4326
Driver: GTiff/GeoTIFF
Size is 10000, 10000
Coordinate System is:
PROJCS["NAD83 / Alabama East",
GEOGCS["NAD83",
DATUM["North_American_Datum_1983",
SPHEROID["GRS 1980",6378137,298.2572221010002,
AUTHORITY["EPSG","7019"]],
AUTHORITY["EPSG","6269"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4269"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",30.5],
PARAMETER["central_meridian",-85.83333333333333],
PARAMETER["scale_factor",0.99996],
PARAMETER["false_easting",656166.6666666665],
PARAMETER["false_northing",0],
UNIT["US survey foot",0.3048006096012192,
AUTHORITY["EPSG","9003"]],
AUTHORITY["EPSG","26929"]]
Origin = (723240.000000000000000,820340.000000000000000)
Pixel Size = (0.500000000000000,-0.500000000000000)
Metadata:
AREA_OR_POINT=Area
TIFFTAG_XRESOLUTION=72
TIFFTAG_YRESOLUTION=72
TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
Corner Coordinates:
Upper Left ( 723240.000, 820340.000) ( 85d36'54.59"W,
32d45'17.80"N)
Lower Left ( 723240.000, 815340.000 ) ( 85d36'54.71"W,
32d44'28.33"N)
Upper Right ( 728240.000, 820340.000) ( 85d35'56.04"W,
32d45'17.69"N)
Lower Right ( 728240.000, 815340.000) ( 85d35'56.17"W, 32d44'
28.22"N)
Center ( 725740.000, 817840.000) ( 85d36'25.38"W,
32d44'53.01"N)
Band 1 Block=10000x1 Type=Byte, ColorInterp=Red
Overviews: 1250x1250
Band 2 Block=10000x1 Type=Byte, ColorInterp=Green
Overviews: 1250x1250
Band 3 Block=10000x1 Type=Byte, ColorInterp=Blue
Overviews: 1250x1250
------------------------------------------------------------------------
-------------------------------------------
Driver: GTiff/GeoTIFF
Size is 11930, 9476
Coordinate System is:
GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.2572235630016,
AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4326"]]
Origin = (-79.902533251890048 ,37.745881181682833)
Pixel Size = (0.000005030208747,-0.000005030208747)
Metadata:
AREA_OR_POINT=Area
Corner Coordinates:
Upper Left ( -79.9025333, 37.7458812) ( 79d54'9.12"W,
37d44'45.17"N)
Lower Left ( -79.9025333, 37.6982149) ( 79d54'9.12"W,
37d41'53.57"N)
Upper Right ( -79.8425229, 37.7458812) ( 79d50'33.08"W,
37d44'45.17"N)
Lower Right ( -79.8425229, 37.6982149 ) ( 79d50'33.08"W,
37d41'53.57"N)
Center ( -79.8725281, 37.7220481) ( 79d52'21.10"W,
37d43'19.37"N)
Band 1 Block=256x256 Type=Byte, ColorInterp=Red
Band 2 Block=256x256 Type=Byte, ColorInterp=Green
Band 3 Block=256x256 Type=Byte, ColorInterp=Blue
--
John J. Mitchell
--
John J. Mitchell
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