[Gdal-dev] Alabama geotiff tiles are showing up in Virginia withinmapserver

[Ed McNierney]

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: +1 (978) 251-4242
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 
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