Just to correct myself the actual distance should be 125.6. :) On Mar 27, 2014, at 11:05 AM, Jesse Clark <je...@corengi.com> wrote:
> Thanks for the info guys. > > GML 2.0 does support srs attributes according to the spec (and JTS claims to > too according to that spec). > > But I'm not sure if my srsName declaration is having any effect. Using 69.1 > miles per degree of latitude (assuming the result is in degrees of latitude) > gives 133.8 miles and the actual distance is 141.0. This difference could be > due to using a 2d projection instead of spherical. > > Zachary you were correct about the coordinate order. It should be long,lat. > > Either way, not being familiar with GML or GIS this is all getting way to > complicated for me as a method to find the distance in miles between two > coordinates of lat/lng. I am just going to use an implementation of the > Haversine function in my app to calculate the distances I need. > > Thanks again, > -Jesse > > > On Mar 27, 2014, at 3:26 AM, Christian Grün <christian.gr...@gmail.com> wrote: > >> Hi Jesse, >> >> as Zachary thankfully pointed out, our implementation only supports GML 2.0. >> It is based on the JTS library [1], which seems to return a >> NullPointerException for geo elements that do not comply with 2.0. I’ve >> slightly updated the error message [2] to make clearer what’s going on. >> >> Best, >> Christian >> >> [1] http://www.vividsolutions.com/jts/JTSHome.htm >> [2] http://files.basex.org/releases/latest/ >> ________________________________________________ >> >> On Wed, Mar 26, 2014 at 10:49 PM, Jesse Clark <je...@corengi.com> wrote: >> Hi All, >> >> I am writing a feature that will rely on geo:distance to give me the >> distance between two points of latitude and longitude. >> >> I am a total n00b to GIS and GML so I may have messed this up, but based on >> a bit of research to figure out how to define the coordinate system and >> based on the example query from the BaseX docs I came up with the following >> query as a test: >> >> import module namespace geo = "http://expath.org/ns/geo";; >> declare namespace gml='http://www.opengis.net/gml'; >> >> let $vancouver := <gml:Point srsDimension="2" >> srsName="http://www.opengis.net/def/crs/EPSG/0/4326";> >> <gml:pos>49.40 -123.26</gml:pos> >> </gml:Point> >> >> let $seattle := <gml:Point srsDimension="2" >> srsName="http://www.opengis.net/def/crs/EPSG/0/4326";> >> <gml:pos>47.68 -122.37</gml:pos> >> </gml:Point> >> >> return geo:distance($vancouver, $seattle) >> >> I have this in a file and am trying to execute it from the CLI with: 'RUN >> [/path/to/file]' >> >> It pukes with this error: >> >> Stopped at [/path/to/file], 12/21: >> [GEO:GEO0002] java.lang.NullPointerException >> >> I am running off of the zip distribution of BaseX so I believe the geo >> module should be included. >> >> Any guidance would be greatly appreciated. >> >> Best, >> -Jesse >> >> _______________________________________________ >> BaseX-Talk mailing list >> BaseX-Talk@mailman.uni-konstanz.de >> https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk >> >> >
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