[Gdal-dev] Need a sanity check on processing imagery

Stephen Woodbridge woodbri at swoodbridge.com
Sat Mar 10 21:16:37 EST 2007


Thank you! for the feedback. I have one question one this part:

Frank Warmerdam wrote:
>> Does this look like a reasonable process? Or is it flawed?
> You are generating files for which the top left corner of the
> top left pixel is at the lat/long location -11.9375,41.4375.
> Is that want you want?  Sometimes people really want the center
> of the top left pixel to be at that point.  If that is what you
> want, you will need to manually adjust the extents "out" by a
> half pixel.

What is the easiest way to do this. Is it as simple as offsetting the 
corners below by 0.5 before doing my projection to latlong?

$ gdalinfo -nomd naip_1-1_1n_s_ut057_2006_1.sid
Driver: MrSID/Multi-resolution Seamless Image Database (MrSID)
Size is 95310, 41990
Coordinate System is `'
Origin = (373650.000000,4588120.000000)
Pixel Size = (1.00000000,-1.00000000)
Corner Coordinates:
Upper Left  (  373650.000, 4588120.000)
Lower Left  (  373650.000, 4546130.000)
Upper Right (  468960.000, 4588120.000)
Lower Right (  468960.000, 4546130.000)
Center      (  421305.000, 4567125.000)

Or do I need to project these first and then offset the results. If this 
is the case, how does one calculate the cellsize of a pixel before doing 
the gdal_warp?


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