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seen Aug 20 '13 at 21:28

Sep
18
accepted Proximity query approach
Sep
18
comment Proximity query approach
Great, this approach works perfectly. Thanks!
Sep
18
asked Proximity query approach
Jul
29
awarded  Scholar
Jul
29
accepted Does a value in srtm dem file refer to the center or corner of a cell?
Jul
29
awarded  Supporter
Jul
29
comment Does a value in srtm dem file refer to the center or corner of a cell?
Thanks. Your second-to-last paragraph answers the question exactly as it describes the meaning of xllcorner/yllcorner rather than the meaning of the filename (which is also useful but wasn't my question). Anyone else with this question should note that the excerpt from Nasa's documentation (first quote above) explains the meaning of the filename not xllcorner/yllcorner. I also think the link to the ASCII grid file on wikipedia is the most relevant reference for anyone else who has this same question.
Jul
29
comment Does a value in srtm dem file refer to the center or corner of a cell?
Thanks this does give some context, given that a cell represents the average height for all records in that polygon then the most accurate way for me to generate a point from each pixel is to treat the value as the elevation at the centroid.
Jul
29
comment Does a value in srtm dem file refer to the center or corner of a cell?
Thanks, you're right, (xllcorner, yllcorner) is ALMOST exactly half a cellsize off from being on an exact degree.
Jul
29
comment Does a value in srtm dem file refer to the center or corner of a cell?
Thanks very much for that link, I thought the format should be documented somewhere but didn't know where to look. This explains it pretty well. It's interesting to note that "To be more exact, these coordinates refer to the geometric center of the lower left pixel" - indicates that the filename references the center of the lower left pixel. I think though that the xllcorner and yllcorner fields in side the file represent the lower left corner of the lower left tile though. Thanks!
Jul
27
awarded  Student
Jul
27
asked Does a value in srtm dem file refer to the center or corner of a cell?