A geometric element defined by a pair of x,y coordinates.

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2
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0answers
582 views

cant find point/polygon intersect using qgis (windows only)

below i describe the method i am using. i have 2 machines: 1 ubuntu linux, qgis 1.4 - intersection works 2 WIN xp, qgis 1.8 - intersection dows not work hopefully, someone will ...
6
votes
2answers
279 views

Why am I getting duplicate ghost points (features), i.e., one point in the feature class but two points?

When editing some of the attributes in a point feature class in ArcMap 9.3, duplicate labels started showing up. When I click on the point, I discovered that the point has duplicated itself BUT there ...
11
votes
4answers
2k views

How to filter wrong GPS points?

I have a database of GPS points. There aren't any tracks, only points. I need to calculate some value for every 100 meters, but sometimes GPS gave a wrong coordinates that lies far from real GPS ...
1
vote
1answer
582 views

Generating Point from Centroid of Polygon Error

I have a feature class of polygons within a geodatabase and I'm trying to generate points based on the centroid of the polygon using the Feature to Point tool in ArcGIS 9.3. However, I end up with ...
8
votes
2answers
1k views

How can I create random points along a polyline in QGIS?

I am trying to create random points along a polyline shapefile in QGIS. Basically, like the 'random points' tool in 'research tools' but for polylines instead of polygons. I have tried converting ...
3
votes
2answers
1k views

How can i select a polygon in MS SQL 2008

I am very new to MS SQL 2008. I got a task to select a polygon from the polygon layer by giving the X-Y coordinates. I already got the script for PostgreSQL for the same thing, but i need it for MS ...
1
vote
4answers
5k views

Prevent drawing of overlapping point symbols - ArcGIS Server/Javascript API

Is there any way in ArcGIS to prevent symbols from being drawn when they overlap each other? I know this is possible for Labels using Placement Properties/Label Weight, but I can't seem to find ...
2
votes
2answers
621 views

Where can I get a multipoint shapefile?

I'm trying to find a multipoint shapefile to do some testing for an application I'm working on, but I cannot seem to find one (and do not have ArcGIS to create one). Can anyone suggest a place to find ...
2
votes
1answer
933 views

Geometryutil, simplify polygon, querytask and query fault error

One of the tools in my app is to draw freehand polygons (counties) to show points (companies) in each county. Everything works great but if the user creates an intersecting polygon then I have a ...
1
vote
3answers
593 views

Divide Line Into Sections Using Points Offset from It

I have track (line) and milemarkers (point). Each point is offset by a different distance. Is there a way to find where each point would intersect the line if going perpeniduclarly out from the line? ...
3
votes
2answers
2k views

Update point coordinates in QGIS after manually moving locations in edit mode

I have imported point coordinates from a database, but I need to manually adjust a lot of the locations. Is there a way for QGIS to automatically update the point locations in the attribute table ...
4
votes
1answer
646 views

Address or reverse geocode a point shapefile

I have a shape file that contains points. I want to do a reverse geocode and give these points an address. Can someone please help me?
3
votes
0answers
76 views

Adding points to represent non-chosen locations

I am looking for a way to set up a discrete choice model in ArcGIS for foraging behavior of individuals, in a grid of 15 locations. To do that I need a point for every possible choice they could have ...
4
votes
5answers
7k views

How do I create a line between two points with a common field?

Does anyone know how I could create a line between two points that have a common code? For example: I have the start and end point of a pipe as a lat/long for a network of pipes, each with a ...
7
votes
3answers
918 views

Creating raster or vector raster from DEM point file?

i have a point shape of 75.000 elevation points in a regular 5 m grid. We now want to create a polygon grid with the elevation points as "centroids". Unfortunately, all attempts to do so fail: I ...
4
votes
4answers
676 views

How to sample raster datasets at ALL points?

I know it is possible to use tools like ArcGis's 'extract sample' tool to extract values at a given number of points. I would like to sample every pixel in a raster, and drill down through all other ...
2
votes
0answers
143 views

How does integrate work with point data sets?

I'm trying to combine point data into clusters and I think I've come up with a method that will work for what I want to accomplish. However, I don't understand why it works the way it does and I'm ...
1
vote
1answer
109 views

Anyone know where I can find a file like this for Pakistan?

Can anyone tell me where I can find a file like this on Pakistan? I found it on ochaonline.un.org I cannot find it when I search on there. ...
3
votes
1answer
2k views

convert list of points to line or polygon

I have a list of Points in a PostGIS table. The rows can be grouped by a date something like: myTable id INT date DATE lat NUMBER lng NUMBER geom GEOMETRY(POINT) now I need a table where all ...
8
votes
4answers
6k views

Get all the points of a polyline

I have some polyline feature objects in python. Now I want to get all the points of polylines. For example, if a polyline has start point [0,0] end point [5,5]. Result: ...
3
votes
2answers
2k views

ArcGIS 10: How to clip point buffer to features in another layer?

I'm on a steep learnig curve here, so aplogies if my question is a one-banana problem. In ArcGIS 10 I have a contour layer that was generated from an ESR ASCII raster file (batyhmetry of the South ...
2
votes
1answer
548 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 ...
12
votes
2answers
799 views

How much sense does it make to average (lat,lon) samples in order to increase 2D accuracy of a GPS location?

Several GPS applications, like this one, or this one, acquire multiple (lat,lon) samples of a given location, assuming that the GPS unit is not moving, and then take an average of the samples in order ...
1
vote
1answer
181 views

QGIS - WGS84 to BC Albers reprojection no curved lines, any idea why? How to snap a line to a point?

I am trying to learn a bit about QGIS. So I thought I would drop in some layers of my Province and then recreate some points representing the BC Albers Central Meridian, and the two standard ...
7
votes
2answers
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 ...
3
votes
2answers
1k views

From point to Grid of polygones or polylines

Is it possible to reconstruct a grid of polygones or polylines from the centroids? I am looking for a arcGIS tool or script that will allow me to reconstruct a grid of polygons or polylines from ...
2
votes
3answers
1k views

Accessing coordinates of polygon

I have designed a polygon in a web page and the coordinates are stored in the database of the type polygon. However when I check the database, I find GEOMETRY - 120B under polygon field. What does ...
3
votes
1answer
257 views

Estimating cline width at multiple points along a trait gradient

In the map below I have 66 (green) points along the midpoint (0.5) for an allele frequency cline across the region (see map). I created the points by placing a point every 25 km along the 0.5 allele ...
8
votes
5answers
7k views

How do I convert a Polygon into a single or all Points?

I want to convert polygons into points. I know how it's done in ArcGis and I think this may sound trivial but it's a serious issue :/. I'll appreciate any hints :)
1
vote
0answers
306 views

Create IPoint with Lat/Long in decimal degrees and Z in feet

I have written an ArcMap v10 AddIn that reads a folder of geotagged JPEG's and creates a new feature class where each point is the geotag information from on of the JPEG's. The issue is: The GPS ...
7
votes
4answers
1k views

Output PostGIS geometry data as centroid or polygon depending on zoom level (GeoServer)

This is what I want: when I zoom out, cities of the country should appear as points and at a certain level when I zoom in, I want them to appear as polygons (showing the area of the city and ...
2
votes
1answer
5k views

How to add points to a point vector layer - QGIS

I have a point layer with multiple data points in QGIS, but I want to add some extra data points to it and adjust some info that we missed because the ground was wet and we needed to go around it. I ...
3
votes
1answer
737 views

OpenLayers Point Feature Vanish on Zoom-In

I use OpenLayers to animate a point moving along a line. To do this I use several map layers and one vector layer to contain one LineString feature and one Point feature. Currently, the animation is ...
2
votes
1answer
421 views

How to move a Point perpendicular from nearest Line?

I want to move Point perpendicular from nearest line or polygon, and the question is how to do that? example, I have points (house number) near roadbed, and I don't want them to intersect roadbed ...
3
votes
2answers
573 views

How to extract cell values from a raster file with Idrisi Taiga?

I need to convert raster cells into points. I use Idrisi and I need to generate a table containing xy (coordinates) and z (cell value).
1
vote
2answers
988 views

How to modifiy how selection highlights are displayed? [closed]

I have got a layer of points that are showed with a litlle symbol. When I select one, a red square comes around it. The problem is that this points are inside other layers (polygons) and some of them ...
3
votes
2answers
400 views

Housenumber(point) angle from line (street)

using arcgis 10 with Point data (Housenumber without angle attribute) and line data (street without angle attribute) I want to create housenumber labels from point with correct angle from nearest ...
1
vote
0answers
308 views

ArcGIS10 Split Line at Point Failing due to Dataset size

Im having an Issue with my Split Line at Point tool. Seems to run if lucky for 700 entries before arcmap/arccatalog falls over. Debugging of the errorlog has produced nothing. The total size of the ...
1
vote
0answers
83 views

How to find locations on a conditional search [closed]

Hope you can help I have a set of points evenly distributed to 500m intervals, and stored elevation. I want to find from a given location any other point with the lowest elevation within a 1,000m ...
5
votes
1answer
3k 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
0answers
245 views

Updating SDE point feature classes with SQL SERVER 2008 R2 [closed]

I am contacting you in hope that you can help me resolve an issue using SQL Server 2008 R2 to push updates to a SDE point feature class. We are using a C# app that uses ArcGIS Runtime to edit the ...
4
votes
3answers
4k views

OpenLayers: Showing a WFS overlay on top of Google Maps

I have found similar questions asked previously, but I still fail to get a simple WFS point layer to work using OpenLayers and Google Maps. The original code I used was based on WFS polygon layers I ...
4
votes
2answers
6k 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 ...
1
vote
0answers
452 views

Error creating IPoint (ArcGIS 10) - Invalid use of New keyword (VBA)

I have some code I wrote in 9.3 that (mostly) works in version 10. I have a UIToolControl that buffers a user-input point based on a mouse click - nearly identical to the sample. This used to work ...
7
votes
6answers
12k views

Creating polygons around extent of similar points using ArcGIS Desktop?

I've millions of points collected for lithology layer. They have used a coding for different types of rocks. I need to create a polygon around the extent of similar points. What is the easiest ...
2
votes
2answers
464 views

Setting up drawing order for point shapefile

I am having a difficulty with creating polyline feature from a point dataset that represents a boundary. This dataset consists of 5084 points which are randomly ordered. I have no Network Analyst ...
6
votes
1answer
6k 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
votes
3answers
615 views

How to create a efficent linestring out of geography points using postgis

I'm trying to create a linestring out of geography points. At the moment I'm doing it like this: select ST_GeographyFromText(ST_Makeline(a.record_point)) from ( select (record_point::geometry) from ...
3
votes
2answers
781 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 ...
1
vote
2answers
2k views

How to create a graphic point by xy value?

I have implemented this code to create point event layer by xy text file, however I'm wondering how to create a point graphic by xy value? This script draws point graphic by mouse down. When I ...