my (java) project uses com.vividsolutions.jts.geom, which provides a distance function. After some googling I finally found that the return value from this function is in central angle degrees, when the CRS is WGS-84 (as it is in my project).
What is an easy to implement and accurate on short distances (no need for long distances) conversion from central angle degrees to meters?
I tried converting by dividing by 360 (from degrees), multiplying by 2 * PI (to radians) and multiplying by 6371000 meters, but my answer is off by quite a lot (176m (QGis ellipsoidal ruler tool) vs 204m (mine)).
I found that GeoTools has some conversion functions included, but I would like to not have to depend on another library, since this code is meant to run on the server and an Android client and is meant to be easy to use by other devs.
EDIT: I also emailed the JTS mailing list, and established that wrapping the distance functions for every possible Geometry.distance(geometry) would be a little tedious.
I decided to use the 111 111 m per degree hack described here: Algorithm for offsetting a latitude/longitude by some amount of meters
Thanks for the help, though!