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

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12
votes
8answers
13k views

Extract raster values at points

How can I extract values from a raster by points. I prefer not in Arcgis. I prefer in Qgis or Mapwindow or other open source gis.
1
vote
0answers
34 views

How to assign a grid of point data to corresponding grid of polygons

I'm using QGIS 2/12.3 I have a point layer with modelled data on a 1km grid, each point has a value (0-5, modelling temperatures) and lies at the centre point of a 1km grid square. I also have a ...
0
votes
0answers
18 views

Create Point Layer from Raster [duplicate]

How would I create an evenly spread Point layer (Qgis), where each Point is located in the middle of a raster cell from a given raster layer?
4
votes
1answer
53 views

tweepy psycopg2 creating points, coordinate system SRID confusing

I am using tweepy and psycopg2 to extract tweets and input them in a postgres table. When I try to insert the point of the tweet I succeed in creating a point in the geom column I create. I however do ...
6
votes
1answer
93 views

Categorising Point Clusters

I have a point dataset of solar farm locations. The points are grouped according to which substation they feed into (see below). I would like to test the hypothesis that electrical output ...
1
vote
1answer
40 views

Make given number of points at evenly spaced on line in QGIS?

I have a shapefile lines representing historical flight paths of aerial photography. I have the number of photos taken for each path and the number of the first and last photo, plus the ID of the ...
0
votes
0answers
78 views

GeoServer SLD Filter rule before PointStacker transformation

I'm trying to apply a filter rule in an SLD, before applying the GeoServer PointStacker transformation (which groups points that are too close to distinguish their icons). This transformation is ...
3
votes
1answer
128 views

Nearest distance between point layer and line layer, QGIS

I have two layers , line and point layer. I need to make line layer which connect all points to nearest line features? Is someone made a plugin for qgis? This is very important tool which missing in ...
2
votes
1answer
537 views

Invalid join selectivity error in postgis 2.1.3

I have 2 tables, one for points and one for polygons. I want to find points falling within theese polygons, so I quered: select p.id, l.id from points p inner join polys l on st_contains(l.geom, p....
2
votes
1answer
62 views

Selecting many maximum points within polygons

I've got a point layer with three values such as high, age etc. and polygon layer with many forest area. What I want to do is to select the 100 maximum (highest) points in every polygon. I can't do ...
10
votes
5answers
19k 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
1answer
42 views

Calculating distance between points from table of UIDs [ArcMap]

I have a .dbf file containing pairs of point feature Unique Identifiers (UIDs), and need to calculate the straight-line distance between each of these pairs. The XY coordinates of the individual ...
1
vote
0answers
28 views

Build network based on shortest distance between points

Is there a way to build a network based on the shortest distances between each point of a point layer. I have occurrence data from species (as points) and want to estimate whether there are one or ...
3
votes
1answer
894 views

How to generate random points with minimum distances between points in multiple polygons

I am looking to create random points for a random stratified survey. There are three different categories being surveyed; for each, I have a single shapefile, each containing a number of polygons. I ...
1
vote
1answer
131 views

How do I assign elevation labels to a custom set of points in QGIS?

Im trying to create topographic surveys using georeferenced images from a drone and a DEM/orthomosaic which has been created using Photoscan. I've managed to create contours and label them with ...
1
vote
0answers
35 views

Create Point - measure distance to point layer- accounting for terrain [closed]

How can I - select a point / location- they pass us a location, that will be a point from one of a series of preexisting layers (which may include lat long or mailing address, but not generally. ...
1
vote
2answers
62 views

Changing point data coordinate system without moving points in QGIS?

I made a mistake regarding coordinate systems and lining up two layers. I have a raster with elevations in EPSG:2949. I created a point data shapefile and entered about 600 hundred points manually ...
0
votes
0answers
14 views

How do you add an image to a point location in ArcGIS 10.3?

I have a set of point locations (groundwater wells) and a graph of groundwater elevation for each location. Is there a way to show the graphs at their respective locations on the map, without having ...
8
votes
3answers
4k views

Label points at regular intervals using ArcGIS for Desktop?

I'm working with lines on roads represented by a large number of sequencial points. Since labeling all of them would make the points impossible to identify, I'd like to know if there is a way to label ...
7
votes
1answer
219 views

How to connect centroids of lines sharing the same intersection in QGIS?

I'm looking for a big help to accomplish the following task: I have this street network of the center of Turin (IT), composed by lines representing streets, and black points representing ...
6
votes
1answer
141 views

How to group 10k points into closest pairs?

I was first faced with a problem of grouping 1000 pairs into unique pairs to minimise the total distance - since this was a small number I solved it using linear optimisation: Part 1 - Basic/Naive ...
2
votes
2answers
314 views

how can we save vector layer as a file in openlayers

Im using mapserver + openlayer for GIS API and im new to GIS. I'm done with drawing line, point and polygon features in openlayer. but not being able to save it in some shapefile afterwards i got to ...
2
votes
1answer
56 views

Polygon data to Point Feature Data

Using ArcGis 10.0. What I am looking for is a way to get point features that are placed in a polygon to have the same "Address" value. This is the same as the "Spatial Join" feature, however, I am ...
12
votes
3answers
14k views

Converting Polygon into single or all Points using QGIS?

I want to convert polygons into points using QGIS. I know how it's done in ArcGIS Desktop.
1
vote
1answer
62 views

Correct Projection for calculating centroids of a group of points?

I have a long list of points covering all of North America for which I would like to calculate the centroid (by grouping points based on the "Name" column). My approach is to take the WGS84 co-...
4
votes
2answers
200 views

Oil and gas well symbology for geoserver

I need to symbolise an oil and gas well dataset in geoserver. I have the dataset symbolised in ArcMap using the standard esri well symbols. Is there an easy way to convert this esri layer file into ...
0
votes
2answers
46 views

remove certain points from point shape file

I have a point shape files with 9674 points.The attribute column has three fields: X, Y and value. Out of these 9674 points, I want to remove 1700 points based on X and Y values (I know the X and Y of ...
6
votes
1answer
430 views

Is there a “Disperse Markers” tool for QGIS?

I am using ArcGIS, but either I would like to use QGIS and maybe want to switch completely later. A have a point overlapping problem, as a result of geocoding of addresses. I have not found any ...
2
votes
1answer
479 views

Getting null values using Point sampling tool in QGIS 2.0.1

I would like to obtain the information of a raster layer at some points. Apparently the Point sampling tool does the job. I have used this tool, and all the raster values extracted at specific points ...
2
votes
2answers
3k 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 ...
5
votes
1answer
422 views

QGIS 1.8 fails to rotate point geometries with rule-based style

I have to do some visualizations in QGIS (1.8.0) and up to now I've been very happy with the new Dialog "Layer Properties -> Style", using the rotation-field to rotate Point-Geometries visualized by a ...
3
votes
2answers
926 views

How to do a Point to Polygon analysis with multiple variables in QGIS?

I have a database of almost 10k crimes, which are divided in to 10 categories and plotted on a map I also have a database of 12k addresses, which are also plotted on the map. I aim to perform a ...
1
vote
1answer
105 views

GeoDjango - save two Point fields, one for geography and one for geometry

Most of the explanations I've read for geography and geometry seem to suggest that one must only use either geometry or geography, and that the only way to use both is to cast/convert between one and ...
7
votes
4answers
5k views

How to extract POINT from a [LINE|MULTILINE]STRING

I'd like to create a vectorLayer in QGIS to display all the points that form a LINESTRING or a MULTILINESTRING stored in a PostGIS DB. I think that I need to transform all points of LINESTRING (or ...
6
votes
2answers
171 views

How to speed up this script in QGIS?

I am a new in PyQGIS, I want to create a Point layer from a raster layer. In table of point layer created, there is 3 fields by name of "X_coord", "Y_coord" and "Azimuth", each point in Point layer ...
0
votes
1answer
58 views

Select by Location using first points of polyline

I am trying to select a point from a point layer that intersect a polyline layers firstpoint and using arcpy. I am getting an error "ExecuteError: ERROR 000622: Failed to execute (Select Layer By ...
3
votes
1answer
93 views

Adding hover pop-up notes to map Arcmap desktop 10.3

I have a layer of points defining a variety of geologic features overlying a global map. I would like the user to be able to hover over a point and see a description of that feature. Hyperlinks ...
1
vote
1answer
216 views

Error when trying to plot legend for geom_point with ggplot2

Here's some mock code to go along with my problem: #read in libraries library(ggmap) library(sp) library(raster) library(ggplot2) #read in country shapefile, project, fortify for mapping with ...
2
votes
0answers
150 views

“Geometry cannot have Z values” exception in ArcGIS Engine

I'm trying to put a list of point features (selected points) into a new FeatureClass. but when I add them to my FeatureClass I get the "Geometry cannot have Z values." exception on the line "buff....
2
votes
4answers
2k views

Finding center point of MULTILINESTRING using PostGIS?

How to find the center point of MULTILINESTRING, which lies on the multiline? I am using SQL in PostGIS
0
votes
1answer
517 views

Try to load GeoJSON object with OpenLayers 3

I'm a bit new to working with OpenLayers 3. I'm trying to load a GeoJSON object in OpenLayers 3 but it display the center only point[0,0], which not even in my GeoJSON object, where I'm going wrong. ...
1
vote
1answer
32 views

inserting value from raster into overlaying point field

I am using ArcGIS 10.3 for Desktop. I am using an etopo bathymetry map and would like to determine the depth of ~50k points in another layer. I am sure there is a simple tool for this but I am ...
0
votes
1answer
74 views

Changing default point symbol?

I am trying to change the default point layer symbol to a set one. For example I have a fire hydrant point layer that is represented by a default point symbol when I import it into my map. Is there ...
0
votes
0answers
3 views

Retaining Raster Point Data Using wms [duplicate]

I have a single band raster being served via geoserver wms. When I view the raster through geoservers built in openlayers viewer I get different point value results than if I ask geoserver for a ...
1
vote
1answer
117 views

Finding and merging lines that touch in PostGIS?

I would like to select and merge segments that touch like in the image below. My table contains single segments with their own id (shown in the figure), I just want to isolate single "group" of ...
3
votes
1answer
79 views

Is it possible to create points that represent lines in QGIS 2.8.Wien?

I want to create points to represent lines from a line layer. This is similar to creating points to represent polygons. Does anyone have an idea on any useful plugin or the best way to do this?
1
vote
0answers
19 views

How do I generate a sampling path by numbering points?

I need to number points from left to right and then the next row of points the numbering must continue from right to left, then again from left to right the row thereafter - and so on, and so on. ...
2
votes
2answers
101 views

Extending line by adding point at end of it using QGIS?

I'm using QGIS 2.8 to modify a line. I need to add a point on one end of this line, and then move this new point further away, leaving the original end point in the same place. I can manage to create ...
2
votes
0answers
28 views

Adding attribute data together within multiple polygons in QGIS? [duplicate]

In QGIS I have two vector layers, the first is a set of polygons and the second is a series of points. Each point has a numerical attribute associated with it and is located within one of the ...
2
votes
1answer
172 views

Selecting features of vector layers based on another vector layer using QGIS?

I am using QGIS 2.12.2. I am using three vector layers (point, polyline and polygon shapefiles) of the region of interest. Any advice in making the selections from one dataset based on the other ...