[GRASS-dev] error in georeferencing points on import with v.in.ascii

Michael Barton Michael.Barton at asu.edu
Sat Jun 8 11:55:48 PDT 2013

I just came across something that is very disturbing.

I imported a batch of points from a CSV file.

2 points have the same geographic location (they are a single archaeological site occupied at different time periods)

I import them into a UTM Zone 30 European Datum 1950 location and they are georeferenced using the following values:

x coordinate = -31415 and y coordinate = 4116150

Once they are in GRASS, however, they show up in 2 different places on my map. I captured the coordinates from the screen and did a query on both points and the results agree. Here are the reported locations of the 2 points

East = -31418.8180586,  North = 4116177.13863
East = -30639.9940711, North = 4116551.27956

The coordinates are significantly different from each AND from the imported coordinates of the 2 points. It looks like one of the points is place close to (but not exactly) on the original north coordinate and the other points is placed close to (but not exactly) on the original east coordinate.

What is going on here???

C. Michael Barton
Director, Center for Social Dynamics & Complexity
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State University

voice:  480-965-6262 (SHESC), 480-727-9746 (CSDC)
fax:          480-965-7671 (SHESC),  480-727-0709 (CSDC)
www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu

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