[gdal-dev] Dateline gap

[Jerl Simpson]

Hello:

I stopped by the #gdal channel on IRC to ask this question.  Thank you
for the help provided there.  I thought it might be better if I asked
a question here so I can better explain what's going on in one spot
and not flood the channel.
I understand this is a pixel center vs pixel edge issue.

My ultimate goal is to get from a netCDF file to a google map overlay contour.
The general steps I've taken, which work all the way up to about
178.29 then it just cuts off.

netCDF -> color-relief PNG using "gdaldem color-relief ...  "
PNG -> Geocoded PNG using "gdal_translate -a_srs EPSG:4326 -outsize
4096 4096 -a_ullr -180.25 90.25 180.25 -90.25" on the PNG (Have also
tried this with just "-180 90 180 -90"
PNG -> tiles using "gdal2tiles.py -s EPSG:4326 -z 0 -n -w google" on
the Geocoded PNG
I guess first question, is my methodology sound?  Maybe there's a
better way/tool to approach the problem.

Following is the output from gdalinfo, other than that, what
information might I be able to provide that could help?

Thank you,

Jerl

gdalinfo for the source netcdf: (My apologies, I'm not certain what is
relevant so I'm including most everything.)

Driver: netCDF/Network Common Data Format
Files: test.nc
Size is 721, 361
Coordinate System is `'
Origin = (-180.250000000000000,90.250000000000000)
Pixel Size = (0.500000000000000,-0.500000000000000)
Metadata:
  NC_GLOBAL#Conventions=CF-1.0
  NC_GLOBAL#cdm_data_type=GRID
  NC_GLOBAL#file_format=GEMPAK
  NC_GLOBAL#location=test.grd
  NC_GLOBAL#history=Direct read of GEMPAK into NetCDF-Java 4.0 API
  NC_GLOBAL#_CoordinateModelRunDate=2011-04-12T00:00:00Z
  UVIN_NONE#long_name=testdata
  UVIN_NONE#units=
  UVIN_NONE#missing_value=-9.999000e+03
  UVIN_NONE#VectorComponentFlag=gridRelative
  time#long_name=forecast time
  time#units=minute since 2011-04-12T00:00:00Z
  time#_CoordinateAxisType=Time
  lat#units=degrees_north
  lat#long_name=latitude coordinate
  lat#standard_name=latitude
  lat#grid_spacing=0.5 degrees_north
  lat#_CoordinateAxisType=Lat
  lon#units=degrees_east
  lon#long_name=longitude coordinate
  lon#standard_name=longitude
  lon#grid_spacing=0.5 degrees_east
  lon#_CoordinateAxisType=Lon
Corner Coordinates:
Upper Left  (-180.2500000,  90.2500000)
Lower Left  (-180.2500000, -90.2500000)
Upper Right ( 180.2500000,  90.2500000)
Lower Right ( 180.2500000, -90.2500000)
Center      (   0.0000000,   0.0000000)

gdalinfo of geocoded PNG:

Driver: PNG/Portable Network Graphics
Files: testWorld.png
       testWorld.png.aux.xml
Size is 4096, 4096
Coordinate System is:
GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0,
        AUTHORITY["EPSG","8901"]],
    UNIT["degree",0.01745329251994328,
        AUTHORITY["EPSG","9122"]],
    AUTHORITY["EPSG","4326"]]
Origin = (-180.000000000000000,90.000000000000000)
Pixel Size = (0.087890625000000,-0.043945312500000)
Image Structure Metadata:
  INTERLEAVE=PIXEL
Corner Coordinates:
Upper Left  (-180.0000000,  90.0000000) (180d 0'0.00"W, 90d 0'0.00"N)
Lower Left  (-180.0000000, -90.0000000) (180d 0'0.00"W, 90d 0'0.00"S)
Upper Right ( 180.0000000,  90.0000000) (180d 0'0.00"E, 90d 0'0.00"N)
Lower Right ( 180.0000000, -90.0000000) (180d 0'0.00"E, 90d 0'0.00"S)
Center      (   0.0000000,   0.0000000) (  0d 0'0.01"E,  0d 0'0.01"N)
Band 1 Block=4096x1 Type=Byte, ColorInterp=Red
  Mask Flags: PER_DATASET ALPHA
Band 2 Block=4096x1 Type=Byte, ColorInterp=Green
  Mask Flags: PER_DATASET ALPHA
Band 3 Block=4096x1 Type=Byte, ColorInterp=Blue
  Mask Flags: PER_DATASET ALPHA
Band 4 Block=4096x1 Type=Byte, ColorInterp=Alpha



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