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Questions tagged [great-circle]

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

2
votes
1answer
52 views

St_Segmentize on CARTO

I need help with the phrasing of this query. I am applying this in CARTO to a file with lines. The following query does not generate a curve as expected. I am new to SQL/PostGIS. select mycartoid....
0
votes
1answer
303 views

Iterate over geopandas dataframe returning nearest point on each LineString

I'd like to iterate through a GeoDataFrame that contains a column of LineStrings and return a list of points; one from each LineString that is closest to a reference point. #### . Import data from ...
2
votes
0answers
93 views

Great circle rendering of satellite ground tracks reversed in southern hemisphere

I'm working on rendering some satellite ground tracks from postgis, through geoserver, and onto openlayers. The python library I'm using to get lat, lon from TLE data isn't perfect, so there are ...
0
votes
1answer
217 views

Drawing curved lines in Carto?

I have a dataset that has the following structure: City_Start / Lat_City_Start / Long_City_Start / City_Dest / Lat_City_Dest / Long_City_Dest What I want to do is create a curved line between those ...
3
votes
1answer
672 views

Formula for the great circle arc between two points (lng/lat coordinates)

I am trying to animate a point moving from one location to another on a map. And I would like the point to travel along the great circle arc between the locations, rather than in a straight line. ...
3
votes
0answers
125 views

What is the correct way to calculate the distance between two Lat Long points with different Altitudes?

If we assume that the altitude is held constant, the great circle distance is correct. However if the radius of the circle is not constant how can the distance be calculated? In my case the altitude ...
0
votes
0answers
291 views

How to calculate the great circle distance along a curved surface?

I know we can calculate great circle distance on a sphere by haversine formula. But what if on a curved surface, as the topography of our real Earth? How do we calculate the surface distance?
2
votes
0answers
225 views

Calculate Great Circle Distance between two point layers via way point

I need to create three distance matrices for around 550 points spread throughout Africa, Europe and Asia. The first matrix represents great circle distances, the second is the shortest distance along ...
1
vote
1answer
69 views

Recommendation for a book for geographical distance calculations [closed]

I am currently writing my Thesis and I need a book covering the geographical distance calculation like haversine and Vincenty. Since I am not of this field, I can't find books which might help me ...
1
vote
1answer
1k views

How to calculate straight line distance from spherical distance

I have longtitude and lattitude coordinates of one point and spherical distance between this and another point on Earth in kilometers (the shortest distance over the earth’s surface). I need to ...
1
vote
2answers
615 views

Confusion regarding distance calculation in R (euclidean distance, “great circle distance”)

OK so considering these two cases: ln1<-SpatialLinesDataFrame(SpatialLines(list(Lines(Line(matrix(c(53.3604464,53.36062,-6.2424442, -6.242413),ncol=2)),ID="a"))),data=data.frame(dummy="a"),match....
2
votes
3answers
2k views

Projecting Cross-Track distance on great Circle?

I have a route formed by some waypoints (black path) and I would like to project it over the great circle (blue path) connecting the starting and ending waypoint. With the work "project" I mean to ...
3
votes
1answer
439 views

How to create Great Circle Mapper style range rings in QGIS?

I'm trying to figure out how to create a range ring from some location (e.g. Broome Airport "YBRM") in QGIS that looks like something in Great Circle Mapper. The issue is about how the range ring ...
3
votes
1answer
1k views

How a draw a circle (on the surface of earth) on a mercator projection?

I would like to use R and leaflet to draw a circle (a real circle on the surface of the earth) on a mercator projection. In the following code, I have the center of the circle (with lng=0 and lat=60),...
10
votes
2answers
1k views

Making Great Circle Arcs which look good on Web Mercator map?

I'm trying to create a map, with data indicating some flights, and want to use Great Circle Arcs, to connect the source and destinations. Basically, I want to do something similar to the famous ...
4
votes
1answer
267 views

Great circles path not curved (in R)? Conventions and convertions problems?

I am given the great circle equations of two paths. The first one is Longitude = 168 degree. and the second one is: tan(Lattitude)=.11 cos(Longitude) + .64 sin(Longitude) However, I am not ...
3
votes
0answers
218 views

Which projection can I use to see alignments on great circles?

I want to put on a QGIS map some historical sites to check if they are aligned. If an alignement exists, the points should stay on a great circle (is this correct?). I want to visually verify this ...
5
votes
1answer
282 views

Is there any online viewer which displays the polygons assuming great circle lines for the edges?

My question is similar to this one: Are there any online WKT editors? The links given in answers have been very useful to me. However, it seems that when the tools in question display maps, they ...
9
votes
1answer
1k views

Project location on a (great circle) path

I've been searching this SE site for quite a few hours now, and I'm still struggling to find a solution to my question. My goal is that given a way in OSM and my location (lat/lon coordinates), I want ...
5
votes
1answer
766 views

Modifying straight line segments to follow geodesic / great circle paths using QGIS?

I have a kml file showing a dodecahedron stretched across the surfce of a globe, which I downloaded here: http://montalk.net/cgi-bin/coordinates.py I would like to re-project this dodecahedron so I ...
7
votes
3answers
2k views

great circles in QGIS and export in 3857 webmap

My plan is to visualize great circles in a leaflet webmap. So coming from this great postgis article and R version I thought it would work like this in QGIS: create line from two points, store ...
2
votes
1answer
1k views

Find latitude of point on great circle given longitude

I am trying to find out wether my implementation has faults and/or if there is a better method. The problem: Given two points (Lat/Long) defined over the WGS84 ellipsoid, find the point lying on the ...
4
votes
2answers
446 views

Moving dead ahead: rhumb line, great circle or none

I think I understand the whole rhumb line and great circle idea but I can't seem to find an answer on this question. Suppose I am driving a car (i don't use ship because I don't want to put the ...
5
votes
0answers
1k 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: https://gist.github.com/Robinlovelace/...
3
votes
2answers
3k 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 ...
2
votes
1answer
580 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" plugin....
6
votes
1answer
491 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 ...
2
votes
1answer
194 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 ...
2
votes
1answer
582 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
votes
0answers
353 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 ...
1
vote
2answers
816 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
votes
1answer
292 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 ...
12
votes
4answers
19k 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 ...
1
vote
1answer
619 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 ...
2
votes
1answer
5k 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
votes
0answers
37 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 ...
1
vote
1answer
617 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 line....
5
votes
1answer
1k 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?
11
votes
1answer
2k 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
553 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 ...
7
votes
2answers
890 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
votes
4answers
628 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
1answer
3k 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
votes
3answers
2k views

Getting 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
1k 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
2answers
8k 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. ...
19
votes
6answers
12k 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 -- ...
18
votes
3answers
4k views

Finding distance between two coordinates in ellipsoid?

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)?