A geometric element defined by a pair of x,y coordinates.
1
vote
2answers
166 views
How to find the center point of MULTILINESTRING?
How to find the center point of MULTILINESTRING, which lies on the multiline?
1
vote
0answers
79 views
Esri ArcGIS plot point
I have created a java function to plot the points on the map, and I need to pass the x-y coordinates and the taskevent as the parameters. I would like to ask what should be the input parameter for ...
1
vote
1answer
195 views
How to find the nearest single point?
I have two shapefiles containing each one set of points, set A and set B. One set is my random selection (set A), the other is a list of communities (set B).
For each point of the random selection ...
1
vote
2answers
387 views
How to offset point perpendicular to line direction in PostGIS
I have a postgis table of points, that are sitting on road centerlines (I've linear referenced them). And the second table with road centerlines themselves.
The point table also has a field roadid and ...
0
votes
0answers
255 views
How to do a spatial join if QGIS 1.8 keeps crashing?
I am trying to perform a simple spatial join (adding polygon data to points) in QGIS 1.8:
target vector: points
join vector: polygons
take attributes of first located feature
keep all records
...
0
votes
2answers
662 views
PostGIS convert geography(Point,4326) to GPS
I got a database with a column of type geography(Point,4326), the data contained looks like 0101000020E610000092E057F66EF73140930035B56CBD4840. How can I convert it to GPS coordinates?
5
votes
1answer
135 views
Given 2 LINESTRINGs with common point, how to extract common point?
I have 2 LINESTRING geometries. I know both share a common point. Using PostGIS for Postgres, what is the cleanest way to extract the common point?
Example with illustration:
How do I extract the ...
2
votes
1answer
197 views
How to create a point table from a remote csv file?
The current approach that I am using to load a csv file into a PostGIS enabled database on a server is the following:
-- create table
CREATE TABLE points(
id int,
lat double precision,
lng double ...
4
votes
1answer
265 views
Is it possible to create a point within a Polygon (not a centroid)?
Is it possible (without writing Python code - sorry I'm not a developer) to create a point layer from a polygon layer but ensure the point is within the polygon? The ftools centroid tool is cool but ...
3
votes
2answers
2k views
How to calculate new point coordinates from distance and angle?
I want to calculate the coordinates of a new point.
What I have: The source point coordinates, the distance (meters) and the angle
For example: I want to create a point within 100 meters and 45 ...
4
votes
3answers
1k views
How do I retrieve start and end point coordinates with Python/arcpy?
How do I retrieve start and end point coordinates with Python/arcpy for a polyline feature class? I expect to pass a segment identifier to a subroutine and have it pass back start and end coordinates. ...
0
votes
2answers
254 views
Handling points in openlayers
I have a several hundred points that I am showing on a map. At the moment, my method of adding the points seems inefficient. I create an array using the following approach:
var features = [new ...
2
votes
0answers
339 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
186 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 ...
6
votes
4answers
594 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 ...
0
votes
0answers
79 views
Move or snap all annotation created from point layer
Et geo is a very good tool, I got angle from nearest line and i snapped all points to another line buffered with an exact position from the road ( 10 points 1:1500) some manual calculation was needed ...
1
vote
1answer
226 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 ...
7
votes
2answers
617 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
598 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
1k 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
245 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
462 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
330 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
635 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 ...
3
votes
1answer
255 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?
2
votes
0answers
51 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
4answers
2k 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 ...
0
votes
0answers
129 views
Plot data on a map [closed]
I've a data set contains three variables: longitude, latitude, population (in USA). I need to plot these data on a map. I use the following code (it works fine):
map("state", xlim = range(lon), ylim ...
7
votes
3answers
440 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
333 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
110 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
64 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
739 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 ...
7
votes
4answers
2k 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
808 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 ...
1
vote
1answer
219 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 ...
8
votes
1answer
331 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
125 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 ...
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 ...
3
votes
2answers
377 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
547 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
185 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 ...
4
votes
3answers
2k views
How do I convert a polygon into a point?
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
179 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 ...
6
votes
4answers
642 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
1k 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
506 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
228 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
322 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).
2
votes
2answers
148 views
How to modifiy how selection highlights are displayed?
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 ...
