## MASON-INTEREST-L@LISTSERV.GMU.EDU

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Subject:

Re: Mason and GIS

From:

Tony Bigbee <[log in to unmask]>

Reply-To:

MASON Multiagent Simulation Toolkit <[log in to unmask]>

Date:

Thu, 6 Jan 2005 17:04:34 -0500

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 ```A minor contribution to this topic: Geotools supports ellipsoid great circle distance calculations, OpenMap supports only spheroids. I ran tests comparing the numerical differences between the two across the earth. But this only matters for specialized cases where high precision is required. An BBN engineer referred to this URL as well: http://www.ga.gov.au/nmd/geodesy/datums/distance.jsp Some example code comparing the two: >> import org.geotools.cs.Ellipsoid; >> import org.geotools.units.Unit; >> import com.bbn.openmap.geo.Geo; >> import com.bbn.openmap.proj.GreatCircle; >> >> //calculating great circle distances using ellipsoid with Geotools >> double km = 1d/1000d; //do the division now and use to convert >> meters to km when desired. >> //create an ellipsoid earth model based on WGS84 >> Ellipsoid ellip = Ellipsoid.WGS84; //only instantiate an Ellipsoid >> once! >> //get the distance in meters given long1, lat1, long2, lat2. Note >> the order! >> //call ellip.orthodromicDistance whenever needed to calculate distance >> double distance = ellip.orthodromicDistance(117.5, 34,117.55,34.01); >> System.out.println(distance*km); >> >> //you can also create your own ellipsoid and make it spherical if >> desired: >> Unit meter = Unit.METRE; >> Ellipsoid sphere = >> Ellipsoid.createEllipsoid("earth-sphere",6378137.0,6378137.0,meter); >> >> //calculate great circle distance using OpenMap spherical model >> //note: coordinates order is different than Geotools >> Float om_distance = >> GreatCircle.spherical_distance(lat1,long1,lat2,long2); I would echo Felimon Gayanilo -- I know a fair number of projects that have used the graphical/GUI aspects of OpenMap successfully. I'm not sure about the graphical/GUI aspects of GeoTools. Tony Bigbee On Jan 6, 2005, at 4:29 PM, Felimon Gayanilo wrote: > How I wished you did not asked me this question...but here we go: > > OpenMap and GeooTools are architecturally (framework, approach) > different. > From my point-of-view as a software engineer, while both adheres to OGC > (OpenGIS Consortium) standards, one has a distinct advantage over the > other > -- it all depends on what you want to achieve and your programming > style (or > preference). ```

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