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

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2
votes
4answers
1k views

Calculate min distance between points in PostGIS

I have point layer in PostGIS database. Help please with query which add for each points in layer distance in attribute table between this point and another nearest point. Thanks! Update Calculate ...
2
votes
1answer
18 views

How to calculate which zip code is closer to which in USA using C#?

I'm not living in USA, and I'm doing a small project for a company based in USA. The point is that, there are businesses and each of them have their address and zip code. Then, I have a form where ...
2
votes
1answer
484 views

Create raster distance around a single point feature class

Okay, so I'm relatively new to ArcMap and I'm trying to use the Fuzzy membership for suitability test. I have a single point feature class that I want to use for this analysis. I know that in order to ...
4
votes
2answers
313 views

clustering points in postgresql to create contour map

UPDATE: To try to make this a little more simple, is it possible to create a query which selects a group of points such that each point in the group is at most X units away from at least one other ...
2
votes
1answer
162 views

using PostGIS to calculate distance of a route over a large area

I'm new to PostGIS and looking to measure the distance of the Pacific Crest Trail which spans western North America from Canada to Mexico. I have a data set containing the lat lon and dates from GPX ...
3
votes
1answer
1k 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 ...
1
vote
2answers
209 views

QGIS spatial join, calculating distance from polygon to point layer

I am trying to perform a kind of 'spatial join' in Arcgis, joining to a polygon layer atributes of the closest feature of a point layer, as well as distance. But 'spatial query' doesn't offer an ...
3
votes
3answers
5k views

Calculating the 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 ...
1
vote
1answer
40 views

How to calculate the shortest geographical distance between a line and a point? [duplicate]

I'm trying to calculate the shortest distance between a line (described as a pair of [lat, long]s) and a point (lat, long) accurately. I've read many Wikipedia pages, but I'm new to the topic. I've ...
3
votes
1answer
84 views

Shortest distance from polygon centroids to a line in QGIS

To get the distance of each polygon centroid from a line, I have tried the Distance to nearest hub algorithm from the Processing Toolbox. The distances I got from the algorithm did not seem correct, ...
1
vote
1answer
48 views

QGIS distance from points to nearest line

How can I get the distances from each point at a shapefile to the nearest line from another? I've tried to follow the directions from Measuring the distance between lines and points in QGIS and ...
2
votes
2answers
36 views

Distance from centre point to other points using QGIS?

I have a question of something I actually thought was pretty simple...I have a few points around a centre point. Now I want to know the distance from each point to the centre point. Is it possible to ...
6
votes
2answers
751 views

Get shortest distance between two geometries in ArcPy

I'm using ArcPy and using a cursor to step through one polygon feature class. For each of these 'source' polygons, I am creating a SearchCursor to find all polygons in a second feature class that ...
5
votes
1answer
631 views

Calculating distance in WGS84 (MySQL and Geoserver)

Here is the environment in which I work: An application using geo-referenced data Database MySQL 5.5, storing georeferenced points A Geoserver server, connected to the MySQL database Here is the ...
3
votes
1answer
46 views

PostGIS: Get closest point between geometry and Multipoint

I think my question is not that difficult for GIS professionals, but i didn't found an answer to my problem (even not in other questions). Problem: I have given two tables (table1,table2) with Points ...
1
vote
0answers
23 views

Finding areas with high POINT density from PostGIS table using Python

I have a PostGIS table with thousands of POINT objects and I want to find areas that have a high density of points. I have the DBSCAN clustering algorithm implemented in Python which does exactly ...
1
vote
1answer
37 views

How to calculate pixel per meter ration according to zoomlevel in google map(bing map)?

I am new here. I need some help. Right now, I got an image and detect two points in the image. I want to calculate the distance between these two points. I got: 1 . x,y pixel value for both two ...
0
votes
1answer
32 views

The ratio Pixel distance to geographical distance?

I have had this problem for several days and I have no idea to solve it. The problem is that I am trying to find out the length and width of ships from a Bing map. I got the location point (lon, ...
1
vote
1answer
129 views

Why do classic google maps and the modern google maps show different types of driving times?

As I am currently working on a project, where driving times are quit important, I've noticed that classic google maps and modern google maps show different types of car driving times. While the ...
0
votes
0answers
14 views

Calculation size limit to creating distance matrix using QGIS?

I have a shapefile of postal code for a city (Montréal). I would like to calculate the distance between all postal code. I tried to run the distance matrix after converting all postal code to a ...
1
vote
1answer
418 views

How to calculate driving distance/time between two points

I am doing some analysis for our fire rescue department where we are comparing actual response times to fires vs predicted response times. The actual response time analysis is straight forward as I ...
0
votes
1answer
124 views

How to set the length of a line using openlayers

I'm trying edit a polygon by changing the length of some lines by code. Found this method to calculate based on the bearing. But I didn't find anything on how to calculate the bearing, before I start ...
2
votes
3answers
60 views

Find point close to points from postgis table

I have a postgis point table with a large list of cities. I need to find duplicates in it, but only if they are 10km close each other, which means that is the same city. For example, I have 5 points ...
1
vote
2answers
181 views

Measure average distance between two lines with common endpoints

I have two shapefiles, each with a set of lines generated from start and end points. One shapefile has the straight lines generated from the XY To Line tool, while the other has lines generated from a ...
1
vote
2answers
201 views

Draw line between points from multiple datasets

I have 2 point datasets and want a tool or script to draw a line between all points in one dataset to all the points in the 2nd dataset. Is it possible? I have tried ESRI "Point Distance" and ...
2
votes
1answer
41 views

Performing Point Distance analysis using Basic level license of ArcGIS for Desktop?

I am using ArcView Version 10.1 and I need to perform a point distance analysis like: What is the distance from A to B-Z, B to A-Z, C to A-Z, etc? What are the steps that I take to do this?
2
votes
0answers
38 views

Calculating Distances between coordinates

I have perused through the other questions that are very similar to mine but am still having some trouble. I have 75 coordinates in WGS84 that I brought in from an Excel table. They are now on my ...
6
votes
1answer
73 views

Statistics: Estimating U.S. population-weighted average temperature from 100+ daily airport station measurements

I have recently signed up for a developer's key for the Census API (http://www.census.gov/developers/) and will be using a Python wrapper class to access the Census database. My goal is to find the ...
3
votes
1answer
54 views

<#> doesn't give a useful distance [duplicate]

I'm new to postgresql/postgis and trying to measure a distance. So st_distance() may be the most accurate, it's the slowest too (as I've read). I read that one can use geometric (instead of ...
3
votes
2answers
43 views

Measuring Continuous Distance of GPS track in ArcGIS Desktop

I am looking for a way to quickly measure the distance covered of GPS tracks of foraging Seabirds. A tool that could give accumulative distance of point to point from the long and lat coordinates ...
3
votes
1answer
51 views

Calculating distances from points to the centre of cells

I am using QGIS 1.8.0 (using older version because I need the Qmarxan plugin which is not available for 2.4.0). I have a study area that has a vector laying of "planning units", or cells over the top ...
2
votes
0answers
24 views

How to calculate distance from point to polygon with a time frame?

Using the Near tool, I knew that I can just calculate the distance of each house to the nearest fire. However, I only want to keep fires that happened in the past 7 years for each house. For example, ...
4
votes
1answer
324 views

How can I make a Postgres/PostGIS ST_Distance_sphere query more efficient?

Within Postgres/PostGIS I have written an SQL query to get the closest distance for each element within a point coordinate table from a polyline table. The query comes back and works correctly, but ...
0
votes
1answer
528 views

Specifying a rectangle as two latitude/longitude pairs, one for center and one for size

I am trying to make sense of the Google S2 library for spherical math (it works like this). I need to get a rectangle for searching for nearby entities in a database, based on a point and a distance ...
4
votes
1answer
120 views

What is an efficient Algorithm to draw a straight line from points?

I have some cross section survey data, which is like this: X Y Z pt_dt 2970969.635 359725.0088 83.4242 1-x 2970968.278 359722.2182 83.2591 1-x 2970941.771 359670.127 83.0655 1-x 2970961.369 ...
2
votes
0answers
80 views

Create circles around a point on a map measuring the radius in hours

Disclaimer: I am not experienced in GIS and hope this question fits in this category. I was wondering whether it is somehow possible to create a circle* around a city, using Google Maps or the like, ...
2
votes
3answers
70 views

How to measure correct distances in a project with OpenLayers background?

I have 3 lat/long points as follows: A = {35.257246,139.721256} B = {35.256541,139.721491} C = {35.256326,139.7203271} 1) Measurement result by Movable Type Scripts: By using the distance ...
18
votes
6answers
11k views

Trilateration using 3 latitude and 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 ...
9
votes
4answers
8k views

How to generate random locations nearby my location?

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 ...
8
votes
3answers
748 views

What kinds of line segments/edges require high accuracy in a true surface-of-the-ellipsoid representation?

I've been musing (and doing prototype coding) for a 'projection free' geographic codebase with your basic point, line & polygon primitives. Rather than dealing with all the sacrifices that come ...
5
votes
2answers
236 views

Is there a way to calculate closest distances to a point without using Near Analysis?

I frequently get asked to calculate distances from a specific point (A drilling well in the middle of the sea for example) to a number of Environmental layers (Protected Areas, Pipelines, Other wells ...
2
votes
1answer
37 views

Calculate distance for point to point based on value in field of first point

I am trying to figure out the best way to calculate the distance for each student from the school they attend. We have 2 shapefiles - the student locations with a field identifying the school they ...
4
votes
3answers
3k views

How to properly utilize DWITHIN Spatial Filter in OpenLayers

Given the following code: var points = []; points.push(new OpenLayers.Geometry.Point(-110, 38)); points.push(new OpenLayers.Geometry.Point(-108, 40)); var lineString = ...
1
vote
1answer
130 views

Calculate distances between polygon centres in QGIS

Is there a practical way to calculate distances between polygon centroids in QGIS? I have a UK city region map divided into administrative units (1 ward = 1 polygon). I want to represent their ...
1
vote
2answers
43 views

How to show average walking distance to closest point in census tract in ArcMap?

Given a map layer of point locations, and a second map layer of census tract polygons for the same area, how would you create a map layer that shows the average walking distance to the closest point ...
-1
votes
1answer
30 views

Buffering algorithm [closed]

Does anyone know the algorithm of buffering? I had difficulty in drawing buffers. So I tried many values to acquire 1km buffer. I found value 0.008966 produces 1km buffer. Then I calculated inverse ...
7
votes
1answer
192 views

How do I calculate Manhattan distance with PostGIS?

I am using the ST_Distance function to calculate the distance between two geometries (a train station and a building) Since I know that all buildings and all train stations are in Chicago, which has ...
1
vote
0answers
22 views

Scale on map requires correction coefficient. But why?

I am computing the distance of a map I am getting from ArcGIS' REST services by using a calculator as provided by this answer. In a nutshell, it uses a GeodeticCalculator for distance computation ...
1
vote
0answers
52 views

How to calculate the average distance among set of points as measure of closeness

I have three series (or tables) of points in PostGIS which I want to compare. I would like to know how "close" each series is when compared to the other two. In other words I would need some measure ...
1
vote
0answers
32 views

How to set a defined distance between nodes to digitize in qgis?

Using QGIS (by now I have the 2.4 version) I would like to set some parameter (I don't know if such exists) that would impose a definite or maximal distance between nodes when digitizing a polyline or ...