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
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1answer
660 views

MySQL GeoSpatial function for ST_Distance_Spheroid? Metric used in return Type of GLength?

Is there a ST_Distance_Sphere, ST_Distance_Spheroid equivalent function in MySQL's GeoSpatial Support? If not, any way to emulate this? What is the metric used in return type of ...
6
votes
2answers
331 views

how to find the point in a country furthest from a boundary

i'm trying to find the point in south africa furthest from the sea or a landward boundary. my method thus far: i obtained a first guess at the centre of the inscribed circle and the three segments ...
8
votes
1answer
678 views

PostGIS - Calculate progressive distance between points on a GPX path

I am attempting to build an elevation profile using PostGIS-PostgreSQL only. I have imported GPX data in my PostGis database, so now I have a table full of the GPS coordinates of the track and the ...
8
votes
2answers
1k views

Calculate Distance between a Polygon and a Point Along a Path

I am very new to ArcGis and am trying to figure out how to do this. Basically, this is what I am trying to do: I have a map of Canada and in it I have polygons representing areas (each about the ...
3
votes
2answers
4k 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 ...
5
votes
2answers
211 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 ...
4
votes
2answers
1k views

tool to find the routing distance between two latitude/longitude points using OSM data

I need a tool to find the distance between two points whose longitude and latitude are given. I am making an application so it will require bulk queries, so i cannot use google maps distance matrix ...
3
votes
1answer
191 views

How to calculate maximum distance to an interpolated value along a contour in QGIS?

I'm planning to enter concentrations of groundwater contaminants collected from well locations into QGIS and then use interpolation functions to create contours of the groundwater plume. Can QGIS ...
1
vote
0answers
145 views

How to create a dynamic distance calculator for selected line feature classes?

My situation: I am relatively new to GIS so forgive me if this is a stupid question. I am working on a project at a park that I am interning at where the goal is to create a single feature with ...
3
votes
2answers
1k views

How to find a point on given line that its distance from another point is given also?

I have this input: (lat1,lon1), (lat2,lon2) - Two coordinates that create the line (lat0, lat0) - Point on this line d - distance I want to find a point (lat, lon), where (lat, lon) is on the ...
2
votes
0answers
700 views

Calculate cumulative distance between points in a dataset in ArcGIS 9.3 ArcInfo

I am working with several point datasets that I have received, with the points representing xy locations with elevation data for several levees in south Louisiana. I would like to be able to calculate ...
5
votes
1answer
382 views

How to compute the distance between centroids and polygons?

Suppose I have an Excel spreadsheet with the latitude and longitude of the centroid of every county in the U.S. I want to know the shortest distance from each county to any part of Oklahoma ...
1
vote
1answer
346 views

PostGIS - table with 3d points with fast ordering by distance

I am pretty new to PostGIS and I am trying to solve the following problem. I need a table with 3D points (x,y,z) that will contain around 1-10million points. I want to be able to efficiently ask the ...
3
votes
1answer
127 views

Method to compute and visualize the closest set of facilities from OSM data

I want to use OSM to extract a set of facilities e.g. school, park, hospital inside a given region. from that, transform the area in grid and for each cell in a grid compute its score mixing the ...
8
votes
3answers
5k 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 ...
4
votes
1answer
1k views

Distances in {Plate Carrée projection - EPSG:4326 - WGS84}

So, "4326 is just the EPSG identifier of WGS84" [3], indeed http://spatialreference.org/ref/epsg/4326/html/ says it is a GEOGraphic Coordinate System: GEOGCS["WGS 84", DATUM["WGS_1984", ...
1
vote
1answer
2k views

distanceTo is giving wrong result in OpenLayers?

Hi i am using distanceTo from OpenLayers to calculate the distance between two locations these are map details Geographic = new OpenLayers.Projection("EPSG:4326"); Mercator = new ...
23
votes
2answers
1k views

How accurate is approximating the Earth as a 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 ...
4
votes
3answers
3k views

Splitting lines automatically at specific distances?

I have a set of polylines I need to split at varying distances from their starting points. In general I'm looking for a something similar to the SPLIT function within the editor tool. There it is ...
3
votes
1answer
2k views

QGIS calculate distance of point along a line

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 Quantum GIS. I hope for a result which will add a new ...
1
vote
2answers
462 views

GeoDjango Order by distance for Model that is linked to User who has a location on their user profile

I need to order my query model by distance, however the point field in question is not on the model class but on the user profile and the i am getting an error when attempting the following. g = ...
1
vote
1answer
755 views

Calculate the distance between two contours

I have two contour polylines (single shapefile) and I would like to calculate the mean, min and max distances between the two lines. Is there a function in ArcMap 10 (ArcInfo license, incl. Spatial ...
5
votes
1answer
529 views

How to find the two furthest points between a group of points?

I have a table with 20000 records and with those columns Shop, longitude, latitude, geom I would like to find a way to find the pair of ths farthest shops between a selection of shops For example we ...
3
votes
2answers
2k views

How to calculate how long an arc second is for a given long/lat?

The title says it all, really. I am wondering what area is covered by a dataset which is one arc second wide. Thanks, Rob
4
votes
1answer
503 views

Calculation of average point distances from one another within a polygon grid

I am working with processed LiDAR data of forested areas in ArcMap 10, with various area based statistics extracted for each 30x30m polygon grid-cell in a shapefile. There are approximately 20,000 of ...
1
vote
1answer
2k views

Measuring on OpenLayers map

These days, I am trying to develop web map using openlayers. I copy source code from here Then I changed code to display my data.B ut it does not work, even map is also not showing. In chrome shows ...
1
vote
2answers
1k views

How to get vector feature information (distance and extent ) on OpenLayers

I have basic WMS layer and vector layer in openlayers. Using EditingToolbar i can draw some features as shown below Then I want to get some information (like distance and extent) of drawn features ...
3
votes
2answers
1k views

How do I get the distance meter value between two geometries in PostGIS?

I have a simple question about calculating distances in 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 : ...
19
votes
2answers
394 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 ...
7
votes
1answer
570 views

Appropriate distance metric for spatial clustering of geographic coordinates

I have a set of locations in geographic coordinates, and I would like to group the points using hierarchical clustering followed by tree-cutting at various "heights" in order to calculate group-wise ...
3
votes
2answers
133 views

How to find the distance within which a set percentage of features fall?

Someone asked a question earlier about finding the number of features within a certain distance of another feature in ArcView. I have the opposite question: is there any way, in ArcGIS 10, to find the ...
2
votes
1answer
432 views

Calculating distance from points to nearest “eastern” polygon

I am using ArcGIS 10, and trying to do the following: I have a layer file of points (industrial facilities), and I would like to calculate the distance from each point to the nearest "eastern" ...
5
votes
1answer
2k views

How do I perform a proximity search with Postgis?

OK, so I downloaded the Geonames database (cities1000) and wrote a small Ruby program to import them into my table (geo_cities). I then added geography column called geog. So after all of that, I ...
3
votes
4answers
2k views

Geodjango- get the distance between 2 points

Sorry to be asking yet another geodjango newbie question. What I want to do is quite simple, I have 2 locations defined by gps coords, lat / long like returned by google maps: ...
1
vote
2answers
544 views

QGIS layers no longer overlay when Enable 'on the fly' CRS transformation is on

My QGIS project has two layers - one retrieved from GADM (administrative boundaries of Guinea Bissau) and another one of the villages collected in the field using GPS Decimal Degrees - D.ddddd. If I ...
4
votes
1answer
2k views

Calculating distance to points in QGIS

Is there a way of calculating the distance to the nearest points in QGIS? In ArcGIS there is a function called Euclidean Distance, which can take an input vector or raster, and generate a raster of ...
2
votes
2answers
758 views

Finding the minimum and maximum distance between an observer and a lat/lon bounding box

I have three points in geographic coordinates (latitude, longitude, altitude). One of the points represents an observer, above the Earth. The other two points define a bounding box. I'd like a ...
4
votes
1answer
368 views

Correct use of the terms geographic, path, and Euclidean distance

I often use the terms geographic and Euclidean distance interchangeably when referring to the length of the shortest straight-line distance between two points on a map. Is this correct? I use the ...
3
votes
2answers
496 views

Distance Calculation Output Does Not Identify Input Points

I'm using ArcMap 10 to do distance calculations between a large set of points, using the point distance calculator. The output table generated gives me distances correctly, but the output categories ...
3
votes
3answers
4k views

Distance between GPS coordinates

Given a database of GPS points, a center GPS location, and a radius R (in meters), how can I find all points in the database that are within a distance of R of the center point? Will the distance ...
8
votes
3answers
548 views

Identification of consecutive points within a specified buffer

I have a point file, hourly relocations of an animal, and I want to be able to place a buffer around each point and calculate the number of subsequent points which are within the buffer zone. I am ...
4
votes
1answer
532 views

How to use/interpret/visualise a distance matrix with unknown coordinates?

How would you go about using a distance matrix where points have no coordinates, i.e. what useful statistics can be made and how to visualise it in some useful way?
4
votes
2answers
4k views

How to use Distance Matrix tool in QGIS?

I have a point data set. Now there are cluster of points based on a field. So I take out one such cluster which has points with same field.I want to find distance between all the points in cluster and ...
8
votes
4answers
7k views

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

Hi 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 ...
5
votes
1answer
4k 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) ...
3
votes
2answers
581 views

Total great circle distance along a path of points (PostGIS)

I am looking for an SQL query that sums the distances between a series of points using PostGIS. The situation is as follows: I have 2 tables: tracks and points. Points belong to a track and thus ...
2
votes
1answer
722 views

How to use Google's Distance matrix on server side?

I am developing a web application wherein i need to find the closest bus-stop from a users location and mark it on a map. I have the list of bus-stops on my server. I am using Google's Distance Matrix ...
3
votes
1answer
635 views

clip linestring by length

Is there a way to clip a linestring based on distance? For example, linestring from a to b is 150 meters. I would like to get the linestring from a to a point that is is 75 meters away from a ...
1
vote
0answers
109 views

Calculate Point C using distance and bearing from points A and B? [duplicate]

Possible Duplicate: Calculating Lat/Lng X miles from point I'm from old school so have not done math for ages. So I need some help to solve this problem, please :) I have two points such ...
14
votes
1answer
657 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 ...