[gdal-dev] Can't get gdalwarp to create a raster in Mercator-2SP projection?

[Patrick Sunter]

Hi,

As part of testing GDAL's NetCDF drivers projections, I've been trying
to gdalwarp a Geotiff file from a UTM projection to Mercator-2SP
(http://geotiff.maptools.org/proj_list/mercator_2sp.html).

Thinking I should file this as a ticket? But thought I'd post here first.

I've tried 2 approaches to specifying the target SRS as Mercator-2SP,
and in both cases the resulting files comes out as Mercator-1SP:

1) Specifying using Proj4 (the 'lat_ts' paramater specifies a std
parallel and differentiates from Mercator-1SP
gdalwarp -t_srs '+proj=merc +lat_ts=-45 +lon_0=145 +x_0=0 +y_0=0
+ellps=WGS84 +datum=WGS84 +units=m +no_defs' melb-small.tif
savedResults/Melb_USGS/refactored_gdal/melb-small_M-2SP.tif

Resulting gdalinfo projection section:
PROJCS["unnamed",
    GEOGCS["WGS 84",
        DATUM["WGS_1984",
            SPHEROID["WGS 84",6378137,298.257223563,
                AUTHORITY["EPSG","7030"]],
            AUTHORITY["EPSG","6326"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4326"]],
    PROJECTION["Mercator_1SP"],
    PARAMETER["central_meridian",146],
    PARAMETER["scale_factor",1],
    PARAMETER["false_easting",0],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]]]

2) Specifying the full requested OGC WKT:
gdalwarp -t_srs 'PROJCS["unnamed", GEOGCS["WGS 84", DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.257223563, AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]], PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433], AUTHORITY["EPSG","4326"]],
PROJECTION["Mercator_2SP"], PARAMETER["central_meridian",146],
PARAMETER["standard_parallel_1",-45],
PARAMETER["latitude_of_origin",0], PARAMETER["false_easting",0],
PARAMETER["false_northing",0], UNIT["metre",1,
AUTHORITY["EPSG","9001"]]]' melb-small.tif
savedResults/Melb_USGS/refactored_gdal/melb-small_M-2SP.tif

Resulting gdalinfo projection section: