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I have a .tiff image that I am trying to overlay in google earth. For that I require to georeference it first. The image projection is UTM with NAD83 as datum. I know the lat/long of the four corners of the image.

I am doing the following way:

  1. gdalinfo to get the four coordinates.
  2. gdal_translate to specify lat/long info
  3. gdal2tiles.py to tile the image.

The only thing is bugging me is that I never specified UTM and NAD83, then how come it can overlay my image? Does anybody know how to specify this projection information?

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2 Answers 2

follow this way:

  1. Find your spatial reference code from here

  2. Learn your tif file upper left coordinate and lower right coordinate.

  3. use this command for making it coordinated:

    • gdal_translate -of GTiff -a_ullr ullat ullon lrlat lelon -a_srs EPSG:4269 input.tif output.tif
  4. use this command for mercator:(epsg:3857)

    • gdalwarp -of GTiff -t_srs EPSG:3857 input.tif output.tif
  5. then use gdal2tiles.py to tile.

i hope it helps you....

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Thank you for the answer. But I need to overlay my UTM Projection onto google earth which uses WGS84 as datum. So shouldn't I set the target reference system to ESPG:4326 ? –  Akd Jun 12 '12 at 17:40
    
According documentation and test: -a_ullr ulx uly lrx lry or with lat/lon terms -a_ullr ullon ullat lrlon lrlat is the correct way to use the command. –  zetah May 27 at 22:55

Akd @ "But I need to overlay my UTM Projection onto google earth which uses WGS84 as datum. So shouldn't I set the target reference system to ESPG:4326 ? – Akd Jun 12 '12 at 17:40"

Aragon's gdalwarp to EPSG:3857 is good for Google. See http://wiki.openstreetmap.org/wiki/EPSG:3857 for more.

(Answering the comment followup-question with an "answer", because that seems to be a low-rep newbie's only option.)

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