[gdal-dev] gdal datum shift

[Brian Wilson]

Trying to get a raster to go from NAD83 to NAD27 with gdalwarp. Can't see
any way to tell how it is choosing to do it. Is this documented anywhere?
Is there any way to make it verbose so I can tell if it's trying?

I ran it through strace and watched it open a file called gdal_datum.csv but
of course can't tell what it's trying to do.

I found this post from Frank which implies it tries to be smart and figure
out the transforms without my help:
http://fwarmerdam.blogspot.com/2010/03/in-last-few-weeks-i-believe-i-have-made.html

But it's not working and since I don't know how to tell what it's doing I
can't intelligently ask for help. :-)

Thanks for your patience with a n00by

Brian

Command I am using:

gdalwarp -of HFA -co COMPRESSED=YES -t_srs
ESRI::NAD_1927_StatePlane_Oregon_North_FIPS_3601.prj 11s5w34f_color_ne.sid
11s5w34f_color_ne_nad27.img

Output is in the right coordinate space (it's moved from meters to feet) but
has that familiar 10 or so meter shift we get around like the NAD83-NAD27
transform failed.

The input file SRS looks like this

Coordinate System is:
PROJCS["NAD_1983_HARN_StatePlane_Oregon_North_FIPS_3601",
    GEOGCS["GCS_North_American_1983_HARN",
        DATUM["NAD83_High_Accuracy_Regional_Network",
            SPHEROID["GRS_1980",6378137,298.257222101]],
        PRIMEM["Greenwich",0],
        UNIT["Degree",0.017453292519943295]],
    PROJECTION["Lambert_Conformal_Conic_2SP"],
    PARAMETER["False_Easting",2500000],
    PARAMETER["False_Northing",0],
    PARAMETER["Central_Meridian",-120.5],
    PARAMETER["Standard_Parallel_1",44.33333333333334],
    PARAMETER["Standard_Parallel_2",46],
    PARAMETER["Latitude_Of_Origin",43.66666666666666],
    UNIT["Meter",1],
    AUTHORITY["EPSG","102326"]]
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