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

[Michael Barton]

Here is the command:

v.in.ascii --overwrite input=/Users/cmbarton/sites_out/sites_out.csv output=sites_test separator=, skip=1 x=15 y=16 cat=0

Here is the projection

g.proj -p
-PROJ_INFO-------------------------------------------------
name       : Universal Transverse Mercator
proj       : utm
zone       : 30
no_defs    : defined
datum      : eur50
ellps      : international
towgs84    : -131,-100.3,-163.4,-1.244,-0.020,-1.144,9.39
-PROJ_UNITS------------------------------------------------
unit       : Meter
units      : Meters
meters     : 1


Here is the csv file:



Once imported, take a look at the sites in the lower left. You can see the pairs of sites that should be the same location.

Michael
____________________
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











On Jun 8, 2013, at 12:37 PM, Markus Metz <markus.metz.giswork at gmail.com>
 wrote:

> On Sat, Jun 8, 2013 at 8:55 PM, Michael Barton <Michael.Barton at asu.edu> wrote:
>> 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???
>
> Can you provide CSV file with the 2 points and the exact commands you
> used? A simple import should not change the coordinates.
>
> Markus M

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