[gdal-dev] Dateline gap

[Joaquim Luis]

Jerl,

I would do that with GMT. By using ps2raster you can convert any GMT 
figure (in geogs of course) into KML, and GMT has excellent care of date 
line transition issues.

Joaquim

> 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
>
>
>