[Proj] Lat/long to utm easting error
dersh at alum.mit.edu
Wed Jan 5 19:18:45 EST 2011
I have run into something that I don't understand, and I hope someone can help explain.
I was doing some conversions of points, and ran into a problem. I finally narrowed it down to the following:
If I take two points, at the identical longitude, with a small change in latitude, and convert them each to UTM, I would expect nearly identical easting values. But I am not seeing that. For example:
cs2cs +proj=latlong +datum=WGS84 +to +proj=utm +datum=WGS84 +zone=17 -r
254524.57 4722707.58 0.00
254520.47 4722591.80 0.00
Above there is ~4 m easting difference, with just a small (~120m) change in latitude. Since these points are exactly North-south of each other, shouldn't they have the same easting, at least when they are this close to each other in latitude?
Thanks much for any explanations,
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