The measure of separation between two entities or locations that may or may not be connected, such as two points.
1
vote
1answer
218 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
100 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 ...
7
votes
2answers
2k 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
760 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
774 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 ...
14
votes
1answer
493 views
How accurate is approximating the 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 ...
4
votes
3answers
2k 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
1k 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
284 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
552 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
351 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
510 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
330 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
867 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
718 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
502 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
340 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
409 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
109 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
327 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" ...
3
votes
1answer
797 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 ...
2
votes
4answers
1k 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
294 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
votes
1answer
927 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
536 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
217 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
399 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
3k 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 ...
6
votes
3answers
399 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
381 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?
3
votes
2answers
2k 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 ...
7
votes
3answers
4k 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
2k 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
391 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
612 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
350 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
104 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
530 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 ...
3
votes
3answers
1k views
How do I determine the center point of several features in OpenLayers?
I have several polygons being drawn on a map, usually representing a country or province or state. Depending on some chosen data, different regions may be selected, so what I was hoping is that ...
4
votes
1answer
235 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
votes
1answer
1k views
How to find nearest point for each point in current layer?
I have a point layer and want to know the distance of nearest point of current layer for each point in the layer.
I found some tools in ArcToolbox about it , but they need two layers for input and ...
4
votes
4answers
1k 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 ...
0
votes
0answers
514 views
Radius of Curvature Python/Arc, how access x,y coordinates
I have a polyline in ArcMap 10 and I am able to script the length of the line in Python using this bit of code:
#Calculate Radius of Curvature
#try:
# Import system modules
import sys, string, os, ...
5
votes
1answer
205 views
How do I get the upstream distance to all points in a DEM from a single downstream point?
I want to get the upstream distance to all points in a DEM from a single downstream point. The goal is to create a "downstream distance to a point grid". This then would allow me to create "distance" ...
5
votes
1answer
460 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 ...
4
votes
3answers
340 views
How to efficiently find points within an elliptical area?
Using PostGIS 2.0.0 I need to filter the results of a function, which returns many POINTs, to find the ones that lie within an elliptical area defined by two points and a distance (all parameters ...
10
votes
3answers
2k views
How to cluster spatial data in R?
I am very new to R, so please bear with me : >
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 ...
3
votes
1answer
875 views
MS SQL Server's STDistance output differs from Google Earth/Maps straight line distance
I am testing SQL Server STDistance function in the following way:
DECLARE @g geography;
DECLARE @h geography;
SET @g = geography::STGeomFromText('POINT(53.553813 9.99158)', 4326);
SET @h = ...
7
votes
3answers
194 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 ...
5
votes
1answer
559 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 ...
