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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7
votes
3answers
253 views

What's a term for Sea Level Distance which is usable by novice users?

I've been using the term Sea Level Distance to describe the total length of a line string where I ignore the elevation and just calculate the distance from point to point along the ellipsoid and sum ...
12
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2answers
15k 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 : ...
8
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1answer
2k 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 ...
4
votes
1answer
347 views

Projecting gps data to get length of resulting line shape in ArcMap 10.0

I have gps data in WGS84 geographic coordinates. I will use the gps data to build a line shape in ArcMap 10.0. The data falls in UTM 15N. To get most accurate length of line, should I project the ...
2
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3answers
11k 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 iso-...
2
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2answers
1k 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 ...
3
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2answers
2k 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 ...
15
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1answer
9k 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 ...
4
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1answer
2k 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?
11
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1answer
17k 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) ...
2
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1answer
2k 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
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1answer
2k 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 ...
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0answers
199 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 as A(...
5
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1answer
1k views

Calculating radius / buffer on EPSG 3785 in meters vs buffer in WGS 84 in meters

The goal is working in EPSG 3785 and in particular Google Maps, one wishes to render (on a tile) a circle of a given radius in meters. The rendering is done in pixels. I would guess that one could ...
4
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4answers
5k views

Using a list of geographic locations, and determining the X closest locations to a user-defined location

I've got a list of geographical locations in an Excel spreadsheet. I want users to be able to search for a user-defined location, and then have the X number of closest locations from the list pulled ...
5
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1answer
2k views

Transform polygon to equivalent circle, QGis

I have a polygon and I'd like to find the radius of an equivalent circle from a particular point within the polygon. The polygon would have a large (infinite) number of points evenly distributed ...
5
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2answers
1k views

Plugin for average distance from node to polyline in QGIS?

Is there a plugin available that will calculate this? EDIT 1: The red polyline is the average distance of the point to the black polyline. The red polyline is what I want to display. Alternatively, ...
11
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2answers
4k views

Measuring distance in spherical Mercator vs zoned UTM

I've got points in WGS84 lat/long and I'd like to measure "small" (less than say 5km) distances between them. I can use the haversine formula from http://www.movable-type.co.uk/scripts/latlong.html ...
5
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2answers
40k views

Looking for a Tool to Calculate Distance Between Points (Between Layers)

I am a college student using ArcEditor 10.0 for a semester project measuring distance to hospitals from census tract centroids. This is my first time using ArcGIS, and I have no formal training. So ...
6
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2answers
8k views

java vividsolutions jts wgs-84 distance to meters

my (java) project uses com.vividsolutions.jts.geom, which provides a distance function. After some googling I finally found that the return value from this function is in central angle degrees, when ...
2
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1answer
3k views

Using a geodjango PointField with geography=True, my distance calculations are wrong

Here's my model: class ExchangeArea(models.Model): """ An Exchange Service Area, calculated from a phone exchange and surrounding census tracts. """ coordinates = models.PointField(...
5
votes
2answers
624 views

PostGIS ST_Distance vs. pgRouting

I am looking to create a city directory web app, and the site will need to be able to calculate distances between two geospatial points (like the distance between the user and a restaurant, or the ...
5
votes
1answer
1k views

Distance between points and polygons in QGIS / PostGIS

I need to work out the distance between a table of polygons and a table of points. The table of polygons has different site boundaries, and the point table has points relating to each of the site ...
2
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2answers
2k views

MySQL Query to fetch all cities and POI's near the route

I'm implementing alghorithm to search POI near the route (array of Lat, Long points). My problem is that I don't know how to calculate distance beetween line segment and POI. Look at picture that I ...
3
votes
1answer
1k views

How do I query for all polygons within a distance from a point?

Call me stupid, but somehow I couldn't figure out how to do the following. I've got a testing shapefile with 18 features, which I successfully imported into GeoDjango (1.3, running on Spatialite). As ...
10
votes
2answers
9k views

Distance between lat/long points

I am attempting to calculate the distance between two latitude/longitude points. I have a piece of code that mostly works that I yanked from this post but I do not really understand how it works. ...
8
votes
1answer
5k views

Calculate distances between series of points in postgis

I have a postgres/postgis table containing a series of sequential points. I want to add a new column to the table which contains the distance between each point and the first one, and so forth until ...
3
votes
3answers
2k views

Looking for a Java library for tracking positions, and querying regions

I have a deceptively simple requirement to create a software component to record and update some mobile position information, then be able to perform simple queries concerning mobiles in a particular ...
4
votes
2answers
410 views

Total newbie. Creating map from aerial photo of golf course in QGIS

I have a aerial photo in tif with a tfw file of the golf course that I work at. I would like to create vector data of different features on the course such as greens fairways tees, etc. to calculate ...
7
votes
3answers
340 views

How to check if parcel is located by golf course

Is there any simple way for me to run millions of parcels through some type of script to see if a shape file parcel is on a golf course? For example if I have a layer that has all the golf courses and ...
4
votes
1answer
1k views

Calculate coordinate ( lat / long ) with another coordinate and distance

I already have a formula that can calculate the distance between 2 geographic coordinates: public function getGeoDistance(Coordinate $geoCoord1,Coordinate $geoCoord2){ if(is_object($geoCoord1) &...
7
votes
2answers
400 views

Metric/parameters to compare length of polyline

What would be a good metric to compare the length of two polylines? A very naive approach would be to define a maximum delta which the two lines can differ. I'm looking for more approaches. For ...
4
votes
1answer
576 views

No difference between distances measured in projected and non-projected data

I'm performing measurements of distances in Km between a lot of localities by using the "Point Distance" in ArcGis 9.3. I realized that the results obtained after using projected coordinate system are ...
5
votes
5answers
1k views

Getting a square mile bounding box anchored by coordinates?

Let's say I have a lat/lng coordinate pair. I want to determine the coordinates that would create a square mile box. The existing coordintae pair would be the top left of the box, and the coordinate ...
18
votes
3answers
15k 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 ...
11
votes
2answers
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 ...
3
votes
2answers
900 views

Test case for geo-distance implementation?

I wrote a method, based on this presentation, that filters points based on their proximity to a target point. I would like to write a few test case. What would be good test cases for this method? // ...
2
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1answer
1k views

How is distance between zip codes calculated?

Specifically, where can I find a database of zip codes, their lat/lon centers, and intervening "obstacles" (for example, zip codes that are geographically close but separated by the Chesapeake Bay).