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I am a novice when it comes to GIS systems and information. But, I am having a real problem trying to wrap my brain around a specific value that gdalinfo puts out.

Here is what gdalinfo shows from my GeoTiff file.

[bwalker@localhost tmp]$ gdalinfo Denver\ SEC\ 93.tif
Driver: GTiff/GeoTIFF
Files: Denver SEC 93.tif
       Denver SEC 93.tfw
Size is 16635, 12391
Coordinate System is:
PROJCS["Lambert Conformal Conic",
    GEOGCS["NAD83",
        DATUM["North_American_Datum_1983",
            SPHEROID["GRS 1980",6378137,298.2572221010002,
                AUTHORITY["EPSG","7019"]],
            AUTHORITY["EPSG","6269"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4269"]],
    PROJECTION["Lambert_Conformal_Conic_2SP"],
    PARAMETER["standard_parallel_1",38.66666666666666],
    PARAMETER["standard_parallel_2",33.33333333333334],
    PARAMETER["latitude_of_origin",37.5],
    PARAMETER["central_meridian",-107.5],
    PARAMETER["false_easting",0],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]]]
Origin = (-380521.035404817666858,291529.854634510295000)
Pixel Size = (42.334666405531003,-42.334857259625188)
Metadata:
  AREA_OR_POINT=Area
  TIFFTAG_DATETIME=2015:06:05 10:25:35
  TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
  TIFFTAG_SOFTWARE=Adobe Photoshop CS5 Windows
  TIFFTAG_XRESOLUTION=300
  TIFFTAG_YRESOLUTION=300
Image Structure Metadata:
  COMPRESSION=LZW
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  ( -380521.035,  291529.855) (111d57'15.54"W, 40d 2'50.37"N)
Lower Left  ( -380521.035, -233041.362) (111d41'25.51"W, 35d19'26.36"N)
Upper Right (  323716.140,  291529.855) (103d42'35.65"W, 40d 4' 8.14"N)
Lower Right (  323716.140, -233041.362) (103d56' 4.30"W, 35d20'39.77"N)
Center      (  -28402.448,   29244.246) (107d49'21.13"W, 37d45'47.67"N)
Band 1 Block=16635x1 Type=Byte, ColorInterp=Palette
  Color Table (RGB with 256 entries)
    0: 255,255,255,255
    1: 255,255,0,255
    2: 255,0,255,255
    3: 255,0,0,255
....

I can not, to save my life, figure out what the "Output" line means?

Origin = (-380521.035404817666858,291529.854634510295000)

Does it have something to do with northing or easting? Can someone please point me to a reference that explains what it means. Or even explain it?

  • It's the coordinates of the origin of your raster. The origin is usually, but not always, the top left corner. – user2856 Nov 1 '15 at 4:34
  • @Luke think of turning your comment into an answer. There might be a difference between cell center and raster/cell edge (half a pixel size). The origin is the center of the rasters local coordinate system for pixel/line coordinates. – AndreJ Nov 1 '15 at 7:31
  • A reference could be gdal.org/…. It does not mention "origin" but defines that The upper left corner of the upper left pixel is at position (padfTransform[0],padfTransform[3]). In GDAL that is the case for both "Pixel is area" and "Pixel is point" images. – user30184 Nov 1 '15 at 9:23
  • So why is the origin (-380521.abc, 291529.xyz)? Why not (0, 0)? And if the Origin at the top left corner, then what does the numbers mean? Being a large number says to me they are relative something. What is that something? – Brad Walker Nov 1 '15 at 19:14
  • These are the coordinates of the top left corner, in the Lambert conformal conical CRS defined by the projection parameters.. – AndreJ Nov 2 '15 at 20:19

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