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Originally published 2009-03-31.

This is a simple JavaScript calculator for figuring out world files. Enter the coordinates of opposing corners of the image. Geographic coordinates should be positive with N/S and E/W chosen for direction from the equator and the prime meridian. For UTM enter either positive or negative numbers for northing and easting, and leave the selectors on N and W. The results can be copied and pasted into your world file. Rotations are not handled in this implementation, so the second and third values will always be zero.

First corner:

Second corner:

Image size:  width: px     height: px



Originally published 2009-03-26.

Long story - short

To project the individual frames for this video I used:

gdalwarp -tr 10000 10000 -s_srs EPSG:4326 -t_srs EPSG:2163 nation.gif nationproj.tif

Long story - long

I finally figured out some of the mojo necessary to get some good out of gdalwarp. For me the key was to understand the "spatial reference system" (SRS) parameters. Key to understanding that was grokking the "+proj" notation used in the proj program.

...continue reading "Using gdalwarp"

This site was lost when the version of WordPress and/or PHP being used got to be too old. I still have access to the database containing the old articles and will be using that to restore some that I found most useful. There may be a new article posted from time to time, also. Just be aware that months or even years between posts doesn't necessarily mean that this site is moribund.