9
votes
Making Great Circle Arcs which look good on Web Mercator map?
You could calculate the Geodesics. Saying you want to show the geodesic from A to B, you could first calculate the distance and azimuth from A to B (inverse Geodesic problem) and then calculate points ...
- 435
6
votes
Accepted
Making Great Circle Arcs which look good on Web Mercator map?
The principles in this blog post transfer over to general purpose PostGIS.
http://blog.cartodb.com/jets-and-datelines/
Basically, use ST_Segmentize on geography, and a bit of magic to slice date-...
- 19.8k
5
votes
Difference between Vincenty and great-circle distance calculations?
My apologies for posting a second answer here, but I taking the opportunity
to respond to the request by @craig-hicks to provide accuracy and timing
comparisons for various algorithms for computing ...
- 3,201
4
votes
Accepted
Great circles path not curved (in R)? Conventions and convertions problems?
In that particular projection - Platte Carre - i.e. just plotting latitude and longitude as if they are cartesian coordinates, your great circle line is a straight line.
> gcIntermediate(c(168,-...
- 4,226
4
votes
Accepted
Lines as Great circles on a map
All comments look great but let me draw your attention to new Beeline plugin (Oct.2017~).
Probably no explanations are needed. Enjoy!
- 30.4k
4
votes
Projecting Cross-Track distance on great Circle?
EDIT: I deleted my previous answer as it was wrong. First big mistake I made was performing dot and cross products using spherical coordinates. One needs to convert them to Cartesian first.
(I didn't ...
- 141
4
votes
Accepted
Interpolating orthodrome between two (lon,lat) points in Python?
I have found a good solution:
pyproj.Geod.npts:
from pyproj import Geod
lon0, lat0 = 10, 10
lon1, lat1 = 20, 20
n_extra_points = 100
geoid = Geod(ellps="WGS84")
extra_points = geoid....
- 183
3
votes
Concept behind longitudes
Trying to put it really simply, the way I see it is this.
If I go out with my compass (or gps, or some other kind of navigation tool) and head north I will eventually get to a point where I can't head ...
- 29.5k
3
votes
Accepted
Concept behind longitudes
Latitude and longitude: theoretical constructs, based on natural phenomenon
Latitude is an empirical measurement — the distance you are between
the pole and the equator — and has been measured for ...
- 63.1k
3
votes
Accepted
Calculating distances with PROJ4J
This function implements the Haversine formula (see the source code here - it is indeed not documented).
The input parameters are geographical coordinates (double lon1, double lat1, double lon2, ...
- 10.2k
3
votes
Plotting great circle lines in Cesium (just getting started)?
Use a Polyline for something like this. Here's a live demo.
var viewer = new Cesium.Viewer('cesiumContainer');
var airportData = {
"EDDM": {
"icao": "EDDM",
"iata": "MUC",
...
- 1,464
3
votes
Accepted
Drawing curved lines in Carto?
A very common mistake when trying to connect points with lines using CARTO is forgetting one or many of the mandatory fields that should appear in the query of your map: cartodb_id, the_geom and ...
- 4,401
3
votes
Formula for the great circle arc between two points (lng/lat coordinates)
You can use GeographicLib, which has bindings to several programming languages. For example, the JavaScript version has an example to compute waypoints between two points.
Essentially, you create an ...
- 41.6k
3
votes
Accepted
How to create Great Circle Mapper style range rings in QGIS?
The best workaround is to clip your circle with a polygon covering nearly the world. Put
Nr;WKT
1;POLYGON ((179.9 89.9, 179.9 -89.9, -179.9 -89.9, -179.9 89.9, 179.9 89.9))
in a text file, and ...
- 76.3k
3
votes
PostGIS Splitting complex linestring over dateline
First of all, this has nothing to do with the dateline, this is a 180W/E issue. And I would also say this is not a postgis issue, this is a problem coming up in the software presenting the data. If ...
- 3,492
2
votes
Difference between Vincenty and great-circle distance calculations?
Whether using vincenty or haversine or the spherical law of cosines, there is wisdom in becoming aware of any potential issues with the code you are planning to use, things to watch out for and ...
- 121
2
votes
Difference between Vincenty and great-circle distance calculations?
It appears that the geopy.distance package offers a function "distance()" which defaults to vincenty(). I would recommend using distance() on principle, as it is the package recommendation, in case ...
- 133
2
votes
Moving dead ahead: rhumb line, great circle or none
I know the question has answered already, but allow me to show you something cool for future use:
A live Google map where you can move the edge markers affecting the great circle and rhumb line same ...
- 21
2
votes
Projecting Cross-Track distance on great Circle?
With PyQGIS it is not difficult to do that. For example, for this situation:
where orange line represents a great circle, next code find these "red points" by using 'closestSegmentWithContext' of ...
- 29.4k
2
votes
Accepted
Recommendation for a book for geographical distance calculations
One place to start is the bibliography provided by the geographiclib of Charles Karney.
This starts at the begining with:
I. Newton, Philosophiae Naturalis Principia Mathematica (3rd edition,
...
- 79.9k
2
votes
Accepted
How to calculate straight line distance from spherical distance
Thanks to trigonometric functions we know that
where is your spherical distance, is the earth radius in km, and stands for "euclidian".
Since the earth is only approximately spherical, you should ...
- 350
2
votes
Accepted
Least-cost path = great-circle path in open ocean? (R) (gdistance)
I think people have unrealistic expectations of what gdistance algorithms can do. With directions=8, any path across a free space will consist of N diagonal steps and then M horizontal (or vertical) ...
- 61.5k
1
vote
Error in mapping connections with great circles
I found a solution on my own (thank you for your suggestion @spacedman).
The problem was due to the way I defined the basemap aestetics. Initially, I was defining the map aesthetics in ggplot()
...
1
vote
Distance between coordinates computation speed: conversion to UTM vs Great Circle
1)
IMHO, If your app were to run on a present-day server/desktop/notebook, be it real or virtual, any amount of effort you put into ramping up the computation throughput will far outweigh the return. ...
- 1,662
1
vote
St_Segmentize on CARTO
looking at this again, I think you've got it working :-)
some of the long-haul routes are showing up as curved, although it's difficult to see - there are a lot of short-haul routes in there.
...
- 20.2k
1
vote
Iterate over geopandas dataframe returning nearest point on each LineString
You might want to try rtree. It is the fastest way to retrieve nearest geometries especially when you have a large number of geometries involved. An example of geopandas itself implementing r-tree ...
- 11
1
vote
Accepted
Projecting Cross-Track distance on great Circle?
I found the answer to my question by using the algorithms suggested on this website.
The idea is to find the along-cross distance defined as:
along-track distance: distance between the start point ...
- 262
1
vote
Confusion regarding distance calculation in R (euclidean distance, "great circle distance")
EPSG 3857 is a Mercator projection, and this is not a suitable choice for distance calculations, generally.
This can be a subtle and tricky topic, and your example brings out an problem very clearly....
- 8,126
1
vote
How a draw a circle (on the surface of earth) on a mercator projection?
One way is to draw in Orthographic and reproject. It's not very generalizable though, and I'm unsure how accurate this is at 1000skm scales. (Looks good for this example compared to Manifold's geog-...
- 8,126
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