Any line bisecting the surface of a sphere into two equal halves.

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0answers
58 views

How to prevent cross-world lines in ggplot world map?

I'm having issues displaying 'great circles' paths and polygons in ggmap, an extension of ggplot2. Please enter the following code to replicate my issues: ...
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2answers
53 views

cross track distance to great cicle line and rhumb line

How to calculate cross track distance to great cicle line and rhumb line? For great circle line, I've tried this formula, but it is not accurate while the distance is less than 0.1nm. For rhumb ...
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0answers
65 views

Google Earth / QGIS projection (great circle line)

Here is my question: 1- Based on a long distance segment ( approx 2000 km) drawn on Google Earth and imported as shapefile in QGIS I want to obtain a terrain profile based on "Terrain Profile" ...
4
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1answer
78 views

Should geometries be drawn using rhumb-line or great-circle paths?

I work with WGS-84 coordinates and, most of the time, my map display (luciadmap) is in Mercator projection. My client is surprised to see that, for a rectangular geometry: the line between the 2 ...
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1answer
52 views

Drawing smooth great circle?

I want to draw smooth great circle in any scale and any distance on a Mercator map. The key problem here is how many intermedia points do I need for different location and distance to draw it smoothly ...
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1answer
40 views

Does PostGIS have a Vincenty Distance calculation?

I have compared some distance calculations between geopy and PostGIS ST_Distance_Sphere, and it seems that PostGIS ST_Distance uses a calculation that is similar to the great circle distance rather ...
2
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0answers
50 views

Air corridor in spherical surface: calculating great circle tangent points with small circles

I have the necessity to draw on a sphere (earth) an air corridor. In the cartesian plane, this corridor is made by some circles and from outer tangents that connect these circles as you can see in ...
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2answers
228 views

Draw great circle rays from a single point along specific directions

How can I draw great circle rays starting from a single given point P (for example, from coordinate [34 N, 116 W] in this map) and along directions D1, D2, ... (for example, 30, 45 and 135 degrees) in ...
2
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1answer
137 views

Can I cross the dateline in CartoDB?

I've created a lovely route map in CartoDB, but one of the lines crosses the dateline (from Colorado to Guam, FWIW) and finds its way there by hitting the dateline north of Alaska, bouncing back ...
4
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2answers
972 views

What's the difference between vincenty and great circle distance calculations?

Python's geopy package features two distance measurements techniques: Great Circle and Vincenty's formulae. >>> from geopy.distance import great_circle >>> from geopy.distance ...
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1answer
194 views

Where to start with great circle maps in CartoDB?

I've pulled together a series of maps in R based on Nathan Yau's excellent Great Circles tutorial and a nice zipcode package The maps show how many people from many zip codes descended on a single zip ...
1
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1answer
127 views

How to determine vector between two lat/lon points

For all the math geniuses out there...given two lat/lon points (point A and point B), what is the simplest way to find the vector needed to reach point B from point A. For example, the vector needed ...
2
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0answers
20 views

Draw cirlcle on Equirectangular projection [duplicate]

I'm trying to draw a circle (actually a great circle) on an equirectangular map to archive something like this http://i.stack.imgur.com/7EliU.png (from here). So I have the lat/lon coordinates of the ...
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1answer
155 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
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0answers
375 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,
10
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1answer
660 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
288 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
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2answers
412 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 ...
13
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4answers
317 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 - ...
3
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1answer
1k views

WGS point to WGS line segment (great circle) distance

How would I go about resolving this in C#? I have a line segment (great circle distance) defined by two Lon-Lat pairs (call them points A and B). A third point somewhere on the Earth sphere. The ...
5
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3answers
1k 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
706 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 ...
7
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2answers
2k 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. ...
13
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6answers
4k 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 -- ...
15
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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)?