Fw: [gdal-dev] gdalwarp offset

Wed Feb 20 08:52:20 EST 2008

Oops!  forgot to reply to the list too.

Doug Newcomb
USFWS
Raleigh, NC
919-856-4520 ext. 14 doug_newcomb at fws.gov
---------------------------------------------------------------------------------------------------------

The opinions I express are my own and are not representative of the
official policy of the U.S.Fish and Wildlife Service or Dept. of Interior.
Life is too short for undocumented, proprietary data formats.
----- Forwarded by Doug Newcomb/R4/FWS/DOI on 02/20/2008 08:51 AM -----

             Doug                                                          
             Newcomb/R4/FWS/DO                                             
             I                                                          To 
                                       "szenttehen at yahoo.com"              
             02/20/2008 08:18          <szenttehen at yahoo.com>              
             AM                                                         cc 

                                                                   Subject 
                                       Re: [gdal-dev] gdalwarp offset      
                                       (Document link: Doug Newcomb)       

Joseph,
      That sounds like a datum shift issue.  Are you sure of the NAD27
datum for the utm 11 source image?  If manifold does project on the fly
like ArcGIS, your image datum may not match the vector layer datum from
which you have the .prj file.    Try using the epsg code for UTM Zone 11N
NAD 83 , i.e.,  -s_srs "epsg:26911"     ( I believe 26911 is the correct
epsg code from the pcs.csv file)

Doug

Doug Newcomb
USFWS
Raleigh, NC
919-856-4520 ext. 14 doug_newcomb at fws.gov
---------------------------------------------------------------------------------------------------------

The opinions I express are my own and are not representative of the
official policy of the U.S.Fish and Wildlife Service or Dept. of Interior.
Life is too short for undocumented, proprietary data formats.

             "szenttehen at yahoo                                             
             .com"                                                         
             <szenttehen at yahoo                                          To 
             .com>                     gdal-dev at lists.osgeo.org            
             Sent by:                                                   cc 
             gdal-dev-bounces@                                             
             lists.osgeo.org                                       Subject 
                                       [gdal-dev] gdalwarp offset          

             02/20/2008 02:43                                              
             AM                                                            

Hi,
 I need to reproject imagery that is too
big for my GIS software package to handle. I am
testing GDALWARP on some
smaller images make sure I am doing things right
before attempting the big image. It almost works, but
has one problem. The command
I am using is as follows:

gdalwarp -s_srs custer.prj -t_srs IdahoSPl.prj t75.sid
t75_sp.tiff

where custer.prj and idahosp.prj are projection files
as shown below. I am
basically reprojecting from UTM zone 11 to Idaho State
Plane Central (which
is basically a custom projection).

Everything executes fine, except that when I using the
reprojected imagery
(State Plane) as a background for my layers (which are
in the same
projection) the image is off by about 60 feet to the
east and a 10 feet to
the south. I am sure it is not my vector layers since
they line up exactly
with the image before it is reprojected (The vector
layers are reprojected
"on the fly" to UTM 11 by Manifold GIS when the I
overlay them on the
imagery before reprojection)

It seems that I am missing some offsets or something,
but I don't see how
since I use the .prj parameters from my vector layer
for the target
projection in gdalwarp. Does gdalwarp run into
problems with the change in datums between the two
projections? Any ideas would be helpful.

Thanks,
Joseph

Custer.prj
ROJCS["IDTM",GEOGCS["GCS_North_American_1927",DATUM["D_North_American_1927",SPHEROID["Clarke_1866",6378206.4,294.9786982]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000],PARAMETER["False_Northing",100000],PARAMETER["Central_Meridian",-114],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",42],UNIT["Meter",1]]

idahosp.prj
PROJCS["NAD_1983_StatePlane_Idaho_Central_FIPS_1102_Feet",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",1640416.666666667],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-114.0],PARAMETER["Scale_Factor",0.9999473684210526],PARAMETER["Latitude_Of_Origin",41.66666666666666],UNIT["Foot_US",0.3048006096012192]]

--

____________________________________________________________________________________

Never miss a thing.  Make Yahoo your home page.
http://www.yahoo.com/r/hs
_______________________________________________
gdal-dev mailing list
gdal-dev at lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/gdal-dev