The great-circle tag has no wiki summary.
14
votes
3answers
2k views
How do I find the distance between two coordinates in an ellipsoid?
Lets say I have two sets of latitude and longitude. How do I find the distance between the two locations if I assume the earth is a perfect ellipsoid (with an eccentricity of 0.0167)?
1
vote
1answer
29 views
How to calculate smallcircle on sphere
I use this python code to calculate a greatcircle:
https://code.google.com/p/pyroms/source/browse/trunk/pyroms/greatcircle.py?r=39
After initializing the greatcircle I can calculate points on the ...
1
vote
0answers
76 views
Lines as Great circles on a map
How can I get line features to appear as great circles on a map, instead of straight lines?
Thanks,
8
votes
1answer
160 views
Great-circle lines in Equirectangular projection
Just to check that I'm on the right track:
Are all great-circles on the sphere and in equirectangular projection (i.e. latitude, longitude pairs) either:
meridians (i.e. going pole to pole)
of the ...
1
vote
1answer
83 views
Point plus distance along great circle using RGeo or WKT
I'm racking my brains (and google) trying to figure out how to get RGeo to do the following geospatial calculation:
Imagine I start off at some arbitrary geographic point (let's say (45, 45) which ...
6
votes
2answers
161 views
Find points of interest near a path?
Imagine a table of points of interest along with lat/long. The user identifies two of these points. I want to do the following:
Calculate a great-circle path between these points
Find all POIs that ...
12
votes
4answers
171 views
Are long lines in shapefiles to be considered geodesics or straight lines in the 2D latlong space?
Is there a definition on how lines connect vertices in the shapefile format?
In the simplest case, imagine a line with only 2 points, from 40,-118 to 40,-112 - that's somewhere random in the US - ...
5
votes
3answers
448 views
Is there a way to get ST_ClosestPoint for Geography type?
Using PostGIS 2.0.0 I'd like to find the point on a LINESTRING that is closest to a given point. The LINESTRING represents a great circle line (ie. geography type). ST_ClosestPoint appears to do ...
3
votes
2answers
414 views
How do I find the points of intersection between a small circle and a great circle?
I only actually need to intersect a great circle arc i.e. the shortest path between two points, with a given small circle.
I found this tutorial for intersecting two great circle arcs, but ...
10
votes
5answers
2k views
What tools in Python are available for doing great circle distance + line creation?
I need to use Python to create a great circle distance -- both a number, and preferably some kind of 'curve' that I can use to draw in a client-side map. I don't care about the format of the curve -- ...
7
votes
2answers
1k views
Distance between lat/long points
I am attempting to calculate the distance between two latitude/longitude points. I have a piece of code that mostly works that I yanked from this post but I do not really understand how it works.
...
