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Oct
16
comment Geometric Operations in GIS Systems
This link geo.javawa.nl/coordcalc/index_en.html solves various problems (line intersections, etc.) using geodesics. The calculations are all done in Javascript and I believe that it calls my Javascript implementation of the geodesic routines in GeographicLib
Sep
24
comment How to calculate the shortest geographical distance between a line and a point?
My solution is given in sourceforge.net/p/geographiclib/discussion/1026621/thread/… this uses C++. However the solution can be implemented in Java too, since the needed functions are in the Java version of GeographicLib
Aug
19
revised What kinds of line segments/edges require high accuracy in a true surface-of-the-ellipsoid representation?
Add information on the closest approach problem
Aug
14
revised Find intercept WGS84 coordinates between two segments defined by (Lat1-Long1 and Lat2-Long2) and (Lat3-Long3 and Lat4-Long4)
Add links
Aug
14
answered Find intercept WGS84 coordinates between two segments defined by (Lat1-Long1 and Lat2-Long2) and (Lat3-Long3 and Lat4-Long4)
Aug
12
awarded  Caucus
Jul
11
awarded  Yearling
Jul
11
awarded  Supporter
Jul
11
answered Projection for polygon intersection confined into one hemisphere?
Jun
25
comment Calculated distance doesn't match Google Earth
And I answered the new question, providing a pointer to pypi.python.org/pypi/geographiclib as a possible way to address your needs.
Jun
24
answered Finding coordinate pair at any given distance along calibrated route?
Jun
24
revised Calculated distance doesn't match Google Earth
Add results of asking GE for distances.
Jun
24
comment Calculated distance doesn't match Google Earth
I checked some old correspondence about Google Earth from 2012. I see that GE back then didn't use spherical formulas for distance. However the results weren't consistent with ellipsoidal formulas either unless the flattening was allowed to depend on the position of the points. I will investigate tomorrow.
Jun
24
answered Calculated distance doesn't match Google Earth
Apr
2
comment What is the approximate error of the Pythagorean Theorem vs. Haversine Formula in measuring distances on a sphere at various scales?
Expand sin(A/2) for A small, using sin(x) = x - x^3/6, and you get this result.
Mar
7
comment Does it make sense to create graticules using UTM meters?
An enthusiastic contributor to Wikipedia started using the term "conjugate graticule" several years ago. But the use of "conjugate" is this context is a real stretch (it's borrowed from the terminology for ellipses). I recommend not using the "conjugate" modifier. (The term "conjugate graticule" no longer appears in Wikipedia.)
Mar
3
comment How do I figure out the grid references (Eastings and Northings) necessary to create a circular 1 mile radius around one location?
I'm not sure what I can add...? Did you try working out the results for X' and Y'? Perhaps you need to know that theta could be given in degrees, and then, of course, theta is in [-180d, 180d] (but you need to make sure that this is compatible with the way you're computing sine and cosine).
Mar
3
answered How do I figure out the grid references (Eastings and Northings) necessary to create a circular 1 mile radius around one location?
Mar
2
revised Given a flight path given in latitudes and longitudes, how do I find another flight path that is parallel to the path given?
Figure offset in second case to do a miter join
Mar
2
answered Given a flight path given in latitudes and longitudes, how do I find another flight path that is parallel to the path given?