# Questions tagged [distance]

The measure of separation between two entities or locations that may or may not be connected, such as two points.

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### Calculating longitude length in miles

Suppose I have the geographic coordinates of "Saratoga, California, USA" as Latitude: 37°15.8298′ N Longitude: 122° 1.3806′ W I know from here that in the case of latitude 1° ≈ 69 ...
21k views

### How accurate is approximating Earth as sphere?

What level of error do I encounter when approximating the earth as a sphere? Specifically, when dealing with the location of points and, for example, the great circle distances between them. Are ...
75k views

### Finding nearest point in other GeoDataFrame using GeoPandas

I've got two geodataframes: import geopandas as gpd from shapely.geometry import Point gpd1 = gpd.GeoDataFrame([['John',1,Point(1,1)],['Smith',1,Point(2,2)],['Soap',1,Point(0,2)]],columns=['Name','ID'...
40k 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 ...
158k views

### Calculating Latitude/Longitude X miles from point?

I am wanting to find a latitude and longitude point given a bearing, a distance, and a starting latitude and longitude. This appears to be the opposite of this question (Distance between lat/long ...
45k 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 floating-...
61k views

### Trilateration using 3 latitude/longitude points, and 3 distances?

I want to find out an unknown target location (latitude and longitude co-ordinates). There are 3 known points (latitude and longitude co-ordinate pairs) and for each point a distance in kilometers to ...
96k views

### Generating random locations nearby?

I am trying to create random locations nearby my location. What i want is to create random latitude/longitude pairs inside a 200 meters circle surrounding my location. This is the formula i came up ...
116k views

### Drawing lines from points in QGIS

I have a point layer and need to draw a line passing through or in the vicinity of the points (up to 0.5m distance between the point and the line). The nodes of the line will receive the attributes of ...
95k views

### Return all results within a 30km radius of a specific lat/long point?

I have a table with a column the_geom which contains data similar to: ...
54k views

### Clustering spatial data in R? [closed]

I have bunch of data points with latitude and longitude. I want to use R to cluster them based on their distance. I have already taken a look at this page and tried clustTool package. But I am not ...
18k views

### What is approximate error of Pythagorean Theorem vs. Haversine Formula in measuring distances on sphere at various scales?

Many people when first trying to calculate distances between two longitude / latitude pairs ask if Pythagorean theorem works as an appropriate distance function. Most often people answer "no, the ...
46k views

### PostGIS nearest points with ST_Distance, kNN

I need to obtain on each element on one table the closest point of another table. The first table contains traffic signs and the second one the Entrance Halls of the town. The thing is that I can't ...
22k 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 -- ...
62k views

### Creating points in specified distance along line using QGIS

I want to use QGIS creating points along the line, but in specified distance. I found two GRASS tools in SEXTANTE Toolbox： v.to.points v.segment I tried v.to.points, setting the maximum distance ...
151k views

### Find features within given coordinates and distance using MySQL

I have a MySQL table with user name, latitude and longitude of the user. I would like to get a list of users who are inside the circle or square of a given latitude and longitude with given distance. ...
44k views

### Finding distance of point along polyline using ArcGIS Desktop?

We need to find the distance of a series of point along a given polyline. We have a polyline dataset repsenting rivers in a catchment, broken up into river reaches (FID 1 through 35 for example). We ... 19k views

### Which tools and methods can be used to create isochrones?

I'd like to get an idea for what's involved in creating isochrones for a series of sites, with a reasonable degree of accuracy to the estimates. A general outline would be great, though my scenario ...
38k views

### Adding Direction and Distance into attribute table in QGIS

I just want to add direction (Bearing: i.e N 25 35 E) and Distance (Length: 125 meters) as my new field in polyline/line data. Is there a Plugin to generate these fields? I tried to used Export/Add ...
682 views

### Precision when working with spatial data in GIS

Is there a basic or introductory study that examines and compares the precision of spatial data when working with varying precison of the data input, like having 1, 2, ... decimal places? with the ...
7k 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)?
24k views

### Algorithm to find nearest point

I have 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 ...
15k views

### Calculating distance to points in QGIS

Is there a way of calculating the distance to the nearest points in QGIS? In ArcGIS Desktop there is a function called Euclidean Distance, which can take an input vector or raster, and generate a ...
11k views

### What is difference between ST_DWithin and ST_Distance for proximity search in PostGIS?

I have records stored in a table with latitude/longitude coordinates stored in a geometry field. I want to find all records nearby a user supplied reference point. Note "nearby" probably means less ...
35k views

### 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 ...
41k views

### Finding distance between two points with GeoSeries.distance

When I want the distance between two points [(117.454361,38.8459879),(117.459880 ,38.846255)] (longitude,latitude) on the earth, I take the GeoSeries.distance method, but the method does not give me ...
26k views

### Getting distance meter value between two geometries in PostGIS

I am using PostGIS. I would like to get the distance between two geometries. I am using this sid : 4269 in meters what i am doing now is this : ST_Distance((a.geom,b.geom)) FROM ... but I am getting ...
2k views

### Monte Carlo simulation using QGIS and pgRouting on optimal sidewalk construction

I am new to spatial analysis and would appreciate some general direction on a project I am attempting, outlined below (I am starting from scratch). GOAL: To find the best locations to install 2000 ...
39k views

### How do I calculate the bounding box for given a distance and latitude/longitude

I need to be able to calculate a bounding box or circle for a given WGS84 latitude and WGS84 longitude, and distance but have no idea where to start! The distance from the start Lat/Lon would be 10Km ... 2k views

### Constructing a Voronoi diagram using a complicated travel time metric

I have in my possession four sets of shapefiles: 1. Locations (points), around 1000 2. Roads (lines), each road has a speed attribute 3. Terrain (polygons), each zone also has a speed attribute 4. ...
51k views

### Calculating minimum distance between points and polygons in QGIS?

I have two vector layers: one point and one polygon and I want to calculate the minimum distance of each point from the polygons (ie the distance from the closest point of the closest polygon). Is ...
19k views

### Calculating shortest distance from point to line using QGIS?

What is the best method to calculate the distance from the nearest road for a series of address points in QGIS, having a very big dataset? (QGIS 2.0.1, Win XP) I read the answers to previous similar ...
20k views

### Calculating distance scale factor by latitude for Mercator

This was really inconvenient topic to google out - so I'm asking for clarification, did I understood things correctly. I'm talking about measuring short distances in Mercator projection (3857). You ...
18k views

### Calculate distance from a Point within a Polygon to its edge

Let's say we have the following point and polygon: poly = Polygon([(0, 0), (2,8), (14, 10), (6,1)]) point = Point(4,4) Because point lies within poly, the distance from the first to the latter will ...
2k views

### How can I represent distance using the dashes or markers of a vector line?

I am a very basic user and dont know the lingo to get to the gist of my question so some background might help. Ive volunteered to create a pre-incident planning system for my rural fire department. ...
5k views

### Projections appropriate for global analysis that preserve area and that preserve distance (but not necessarily in the same projection)

I am looking for a projection (or a set of projections) that decently preserve distances so that I can buffer every country in the world and have a similar level of minimal distortion for each. I ...
1k views

### Creating Buffer Polygon following Elevations using ArcGIS Desktop?

What I'm looking to do is put a 100 m buffer on a polygon, but rather than the buffer being at a fixed width "as the crow flies" I want it to follow the slopes of my Lidar DEM. I have ArcMap (with 3D ...
4k views

### Calculating line with the longest distance inside polygon in QGIS

I want to calculate the "diameter" of polygons in QGIS. The "diameter" is defined as the distance between the two most distant points of the polygon. I couldn't find a fitting ...
24k views

### Getting distance between 2 points using GeoDjango? [closed]

I have 2 locations defined by gps coords, lat / long like returned by google maps: http://gmaps-samples.googlecode.com/svn/trunk/geocoder/singlegeocode.html I need to calculate the distance between ...
5k views

### Connecting line features and determining the length of the longest line

I have a line feature (see image) representing a river that I created using the Stream_to_Feature tool. The attribute table contains several records representing different lines - the problem is the ...
27k views

### Calculate distance between points and nearest polygon in R

I have a data frame with among others longitude and latitude as variables for about 17,000 points. I also have a shapefile consisting of multiple polygons. The points fall inside or outside the ...
15k views

### Calculating distance of point along line using QGIS

I have a polyline (movement path) and points recorded along the line. I would like to calculate for each point the distance along the line in QGIS. I hope for a result which will add a new column to ...
4k views

### What is the right solution (and map projection) to compute distances between points located all over the World?

After my study on map projection I realized that it is very difficult to choose a projection that allows to compute simultaneously the distances between a great deal of points if these points are ...
2k views

### Surface distance on DEM between two coordinates

Given two coordinates on a digital elevation model (DEM), how do I compute the actual distance traveled between the two locations, assuming a straight line route? How will changing the resolution of ...
511 views

### Distinguishing corridors from fragments in a habitat map

I was wondering if someone has delt with this kind of issue before: I want to delineate fragments based on neighboring pixels of the same class (forest) with a distance threshold of 3 pixels (which ...
2k 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 ...
23k views

### Simple PostGIS ST_Distance query for two points from the same geometry table?

Note: This question was published at Stackoverflow at first. I have a geometry table points_table with SRID 4326 and a few points in it. I need to find a distance between a pair of points (features) ...
12k views

### Better Distance Measurements in Web Mercator Projection

I am working with an ESRI stack, storing my layers in a sql-spatial-enabled-SDE- geodatabase (Geometry type, Web Mercator-3857). I am building a web mapping application, so by default, the tiles are ...