351 views

### What is the radius of earth [duplicate]

What is the real radius of earth? Google says 6378.1 km Wiki says 6371 km And there are references for 6378.7 km I'm using maximum radius 6378.7 km in distance calculation in spherical law of ...
24k views

### Geodetic Coordinates And Latitude, Longitude

Would it right to say that geodetic coordinates (phi & lambda) are the same as latitude & longitude?
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### Are ellipsoids a mathematical necessity?

The literature usually just tells us that the Geoid is too complex to describe mathematically and that we therefore fit different Ellipsoids to approximate it. Are these Ellipsoids mathematically ...
23k 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 ...
7k views

### How to find a point half way between two other points?

I'm working on implementing the OSM Mobile Binary format for map data, and because it uses a 16 bit delta for each point along a way, it cannot represent a way if there is a large distance between two ...
6k views

### How can I calculate the distances between my points in sequence automatically?

I am trying to measure distances between points and writing the calculated measure between these points in the attribute table. The points represents a vehicle's location based on GPS data according ...
3k views

### How to calculate midpoint given north/south latitude and east/west longitude?

First, sorry if this questions sound very simple. I am very new to GIS. Given four values of north/south latitude, east/west longitude how to calculate the center point that is correct for all cases ...
1k views

### Dividing a geographic region

I have a certain geographic region defined by the bottom left and top right coordinates. How can I divide this region into areas of 20x20km. I mean in practial the shape of the earth is not flat it's ...
1k views

### How big does a circular geofence need to be for the curvature of the earth to matter? [duplicate]

I'm working on adding geofences to a mobile application. I know the proper way of calculating distance between two points on a sphere is using the great-circle or Haversine formula. I don't know if ...
1k views

### find latlngs that are some x distance away from a point to south to north to east to west

I have a latlng i want to find four points with equal distance from this latlangs in all directions east, west, south an north is there any formula . I am trying to build polygons around higways so ...
2k views

### Why Haversine formula and Web Mercator give different length between two latlng points?

I am calculating the distance between two points given by latlng. However, Google Maps (i.e., web mercator projection) gives me a longer distance than Haversine formula. Which is the most accurate ...
1k views

### Implementing custom (Vincenty/Haversine formula) functions for MySQL vs Using PostGIS?

I currently am using MySQL for all of my relational data. I have hit a crossroads with geo calculations. Since, MySQL does not have good support for spatial functions, I am contemplating on using ...
341 views

### Which spatial-reference system is used by the Haversine formula?

I've been reading Pro Spatial with SQL Server 2012. It discusses the various spatial-reference systems (SRS) that can be used when defining a coordinate system. According to the book, Google uses ...