Mary:
Have a look at this tutorial:
http://nceas.ucsb.edu/scicomp/GISSeminar/UseCases/AssignClosestPointsR/AssignClosestPointsR.html
Uses R, which has a good set of geospatial analysis functions. This web
site has several other examples!
Hope this helps,
Rick Reeves
[EMAIL PROTECTED] wrote:
Hi all,
I recently joined, and have a rather basic question. I'd appreciate any
help to find some R routines to find the closest match to GIS
coordinates. I suspect simply using the Euclidean distance. I could
write some code but I suspect there is some already. I describe three
classes of difficulties below.
1. Sometimes there are simple measurement error differences in GIS from
vine coordinates measurement at different times. This may also relate to
ability to get close to trunk in addition to equipment measurement
error.
2. Sometimes we encounter the problem of matching aerial spatial records
with vines. Aerial and satellite imagery is on a different scales
(pixels) to vine spacing. But we would like to be able to match these as
best we can.
3. Sometimes we want to match kriged clusters to target vine GPS
coordinates.
Typically I have 100 target vines at each of 5 vineyards.
Euclidean distance approx. = square root of ( differences between
Eastings squared plus the differences between Northings squared)
Any help will be appreciated Mary Barnes
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