Spherical geometry is the geometry of the two-dimensional surface of a sphere.
10
votes
3answers
652 views
How to calculate the visible sky percentage
Hi I am writing a project and I am stuck: can anyone explain as simply as possible how to calculate the visible sky percentage?
I have done a satellite survey and have worked out the height of ...
5
votes
2answers
222 views
Does the Chamberlin trimetric projection map (some) great circles to straight lines?
I know that, in general, the Chamberlin trimetric projection maps most great circles on the sphere to some sort of non-straight curve on the flat map.
But what about the 3 special great circles ...
34
votes
5answers
3k views
Why is the 'straight line' path across continent so curved?
This is the result of mapping the straight line path from a point in US to Poland using Distance Measurement Tool.
Also, planes from Asia to US would travel almost over North Pole.
Why is the path ...
15
votes
3answers
5k views
Why is law of cosines more preferable than haversine when calculating distance between two latitude-longitude points?
In fact, when Sinnott published the
haversine formula, computational
precision was limited. Nowadays,
JavaScript (and most modern computers
& languages) use IEEE 754 64-bit
...
11
votes
3answers
3k views
Algorithm to find nearest point
I've a list of a few hundred cities with their latitude/longitude. Given another location (also in lat/long) I need to find the nearest city.
As I don't use any GIS, by now the obvious algorithm is ...
3
votes
1answer
2k views
Lat/Lon/Alt to spherical or cartesian coordinates
On my previous question, it was advised I convert lat/lon/altitude to spherical or Cartesian coordinates. I'm not working near the poles and it would be safe to assume a spherical earth. What would be ...
5
votes
2answers
535 views
Quick way to determine if facing a given lat/lon pair with a heading
I'm looking for a fast way, preferably without trigonometric operations (just multiply, divide, add, sqrt and subtract) to determine if a point is visible. E.g. say I am facing 0 degrees N, I am at ...
4
votes
1answer
590 views
How to do stereographic projection conversion (w.r.t. changing point of projection)?
Given a stereographic point P1 projected from point P, and given another point Q, I would like to know how to transform P1's coordinates to that of a stereographic point Q1 projected from point Q.
...
7
votes
3answers
393 views
Method to generate points in any projection
I am writing an application in ArcMap to generate a grid of points. These points have a very defined layout and I have worked out an algorithm that works great under a projected coordinate system. ...
21
votes
3answers
11k views
Algorithm for offsetting a latitude/longitude by some amount of meters
I'm looking for an algorithm which when given a latitude and longitude pair and a vector translation in meters in Cartesian coordinates (x,y) would give me a new coordinate. Sort of like a reverse ...
