A coordinate-based data model that represents geographic features as points, lines, and polygons.

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2answers
11k views

How to clip a line layer based on polygons with QGIS?

I have a line layer and a polygon layer. Both files have the same SRS. I want in a new shape file only the lines covered by the polygons. I tried in QGIS the Vector -> Geoprocessing -> Clip ...
3
votes
1answer
4k views

How do I find vector line bearing in QGIS or GRASS?

How can one extract the bearings from a set of lines in a vector file? I'm trying to find the bearings of several straight vector line segments (simplified contour lines, actually) and can't figure ...
3
votes
2answers
245 views

restrict quantity of features displayed with OpenLayers

I have 14000 point vector features in the map. Displaying them all is very slow (renders at like 1 fps in chrome). How can I tell Openlayers to only display a subset of them, for example features ...
3
votes
2answers
393 views

Is it possible to add house numbers using the Mapbox Street Vector Tiles source in Tilemill2?

Title says it all. Does anyony know if the house number is included in Mapbox’ vector tiles, and if so how to access it for styling? Thanks for any advice!
3
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1answer
1k views

Creating a radius of influence around points

I have a vector file of points. What I need to do is create a circle with a radius of 12km round each point. Would it be possible to then find out what percentage of my total map is covered with ...
3
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2answers
1k views

Creating seperate layers out of one big polygon shape by using attributes

I try to explain may problem. I have a big polygon shape (> 200 fields). I have the owners of these fields in a column. I need the seperated shapes for each owner. Is there a tool to do that? Is it ...
3
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2answers
3k views

How to subtract Geometry Point Polygons in OpenLayers?

I have two json arrays, one for background polygon and one for other polygon. And from them, I got two polygon layers. backgroundLayer = new OpenLayers.Layer.Vector("Background Layer", {styleMap: ...
3
votes
2answers
127 views

Obtaining OS MasterMap time series data

I am trying to do a research project on changes in Land Cover in a London borough over time. I have access to OS MasterMap data through Digimap (the service that provides this data to universities in ...
3
votes
2answers
139 views
+50

Convert vector point data (shp) to raster (tif) using QGIS

Overall Question: How can I get the rendered tif image to keep the modifications seen in the image produced by map canvas? I am writing a standalone Python script. I have simplified my code below ...
3
votes
2answers
362 views

Can't export customer's shapefile to latitude and longitude

I'm very new to this application so bear with me. I hope that I am missing something very elementary. I have a shapefile supplied by my customer. I need to get the latitude and longitude for each ...
3
votes
2answers
373 views

Merging raster and vector not working

I have 1 vector layer (counties) and 1 raster layer (population density). I have tried merging these two, so that I can examine population density within a county, but I have had no luck. It just ...
3
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2answers
121 views

vector layer, no more editing is allowed

I have a polygon vector layer with already 529 objects but without any attributes so far and now I get the message that shapefiles without attributes are treated as write protected. What can I do to ...
3
votes
2answers
731 views

How to set the color of a feature depending on attributes with PyQGIS?

I'm trying to set the color of a vectorlayer feature depending on the feature attributes with PyQGIS. How do you acces the attributes of a vectorlayer feature?
3
votes
1answer
311 views

Halo in OpenLayers (Line, Vector)

How to make a halo around the line of one pixel? For example, line (vector) hase blue color and its frame (one pixel) the black color. Thanks!
3
votes
2answers
69 views

Using Buffer tool in QGIS?

I am using the Buffer tool in QGIS to put a 30 Meter buffer around a number of points. When I do this the buffer ends up taking over the entire map. enter image description here
3
votes
1answer
11k views

Add feature manually to a vector layer in ol3

I'm trying to add a layer manually to a vector layer with javascript. I can't seem to determine why this is failing: http://jsfiddle.net/Kieveli/f4t6n6v1/4/ I've tried sane coordinates like 16,22, ...
3
votes
1answer
871 views

Save map in raster format from QGIS using compression

Is there a method to save a map in raster format from QGIS using compression? For exemple from "Export map" in ArcGIS there are many options to compress the images depending on the file type (tiff, ...
3
votes
2answers
313 views

Interpolation on set of points in QGIS

Is it possible to perform Interpolation in QGIS with input as a vector layer which has a set of points collected following a specified path?
3
votes
1answer
135 views

How to change the color of vector layer of QGIS in api?

I'm using QGIS-2.4.0 api to develop app in C++. When I add a vector layer to the app, the vector map's color would be random. I used QgsFeatureRendererV2 to get the geometry type of the layer, my ...
3
votes
1answer
144 views

Calculating distances from points to the centre of cells

I am using QGIS 1.8.0 (using older version because I need the Qmarxan plugin which is not available for 2.4.0). I have a study area that has a vector laying of "planning units", or cells over the top ...
3
votes
1answer
352 views

Show alternating contour lines

Is it possible to show only every other counture line? And how do you do that? (Im new to QGIS Lisboa 1.8.0, but even newer to QGIS Dufour 2.0.1, but have used ArcGIS a bit a while ago, and also ...
3
votes
4answers
1k views

High resolution and high detail vector GIS coastline product needed

What is the absolute best vector GIS coastline product available globally? I know of a great product for Africa (page 13 of this PDF http://rmgsc.cr.usgs.gov/ecosystems/docs/...
3
votes
1answer
234 views

Converting map image to GIS

I’m very new to GIS, and I’ve been reading a lot of manuals and information, but I thought I’d ask a couple of questions here. One of my major hobbies is drawing maps of a completely imaginary ...
3
votes
2answers
1k views

Drawing pie charts with vectors on OpenLayers?

Is anyone got any examples of drawing pie charts with vectors as markers on OpenLayers ? Cheers,
3
votes
3answers
230 views

How can I draw squares in PostGIS layers at different angles?

I am trying to draw two squares on a 45-degree angle and then merge them using PostGIS to edit. QGIS can draw squares but only on a perpendicular plane (eg, 0, 90, 180), and I need to be able to draw ...
3
votes
1answer
465 views

MapServer Symbol with Two Colours

I'd like to symbolise a point dataset with a square (or circle) using two colours. This is useful for displaying values collected on both sides of a road (for example). I created two symbols, a ...
3
votes
1answer
605 views

Measurement units not returned in project CRS units

I am attempting to calculate area of country polygons using the field calculator. The layer in question is unprojected WGS84, but I have set the project CRS to World Equidistant Cylindrical (Sphere),...
3
votes
3answers
851 views

How do I draw on a vector map in GRASS?

I have a vector map that has two lines. I want to have the two connected. Is there a way for me to draw a line to connect the two? I am using GRASS gis by the way. The two lines that I want to connect ...
3
votes
1answer
67 views

How do I fill a combobox in QGIS with only points vector layers?

I'm new to writing plugins in python for QGIS. I've been searching on internet for a while and wrote the code below. Even though it fills my combobox, all layers (rasters, vectors of all geometry ...
3
votes
1answer
375 views

How to reproject all the vector files in a folder to a particular projection using ogr2ogr?

We have a folder with all sorts of vector files like tab,shp,dxf. Many of the files are in different projection. I would like to convert all the files to EPSG: 4326 and eventually the non-shapefiles ...
3
votes
1answer
372 views

D3 missing zoom Choropleth + Raster

Following this example and Choropleth from Mike's site I am trying to get: image + vector + choropleth = my map As you can see I lost the zoom capability on the vector layer. I have been trying ...
3
votes
3answers
210 views

Plotting Geo Points with “by arc centered at” Instructions

A recent Supreme Court decision redefined the legal boundaries of California along the Pacific Ocean: http://www.theverge.com/tldr/2014/12/15/7397085/supreme-court-california-boundaries-map I am ...
3
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2answers
165 views

Pyqgis How to merge all the active layers? or layers in the registry?

I was wondering if there is a way to merge multiple layers. I actually would like to merge all layers in the registry programmatically, all of them are point layers and have the same fields. I have ...
3
votes
1answer
392 views

Where to get the modern Constellations as a vector File?

Does anyone know where I can get a vector version (shapefile/TAB) of the modern star constellations for the entire sky? Wikipedia has a SVG - https://en.wikipedia.org/wiki/File:...
3
votes
1answer
175 views

Add more info in the attribute table after executing “Line intersection” in QGIS

I have executed the "Line intersection" tool on a road shapefile. This is under Vector > Analysis Tools > Line intersections. I get an output with attribute table having just two columns: type_1 ...
3
votes
1answer
698 views

Openlayers vector layer don't draw well on chrome (single tile)

I have singleTiled layer in OL (using chrome). The layer don't draw completely unless I pan the map slowly to the south (here is example how the layer keep drawing itself each time I pan) : ...
3
votes
2answers
687 views

How to calculate distances between addresses and cities and coast line?

I am totally new to GIS, and so I apologize if my question is not clear enough. My basic problem is the following: I have about 160,000 Danish addresses with longitude and latitude for each address. ...
3
votes
1answer
225 views

How to calculate the percentage of a Line through Polygons?

I have a straight line which runs through a bunch of polygons, which don't have spacing between them (border to border). Is there an easy way with QGIS to calculate which polygons it passes and by ...
3
votes
1answer
1k views

adding polygon to database in openlayers

I want to add a polygon to the database. I used the following code. The problem is that I am to able to save in database. Whatever polygon I draw on map it gets save temporary and as soon as I reload ...
3
votes
2answers
232 views

Dissolve column based on attribute in another column

I have 3 columns within a polygon layer I'm working with. Column 1 = Landowner, 3 different values Column 2 = Parcel, N different values Column 3 = Management type, 5 different values I would like ...
3
votes
1answer
509 views

How to access the icon of a feature retrieved from text in a vector-layer?

I`m using OpenLayers to show POIs on a map. These POIs are loaded from a textfile and I`m using a Vector Layer to get it onto the map - works great. Now I want to use the cluster strategy to have ...
3
votes
2answers
2k views

How to query which features of all vector layers intersect with a given bounds?

I am writing a Openlayers map app, and wondering whether there's a better practice to query which features of which vector layers intersect with a given bounds.. It's certainly not a good idea to ...
3
votes
1answer
971 views

Why is Openlayers KML-layer undefined when using permalink

I am working on Openlayers to dynamically load KML tracks on map. I want it to load filtered KML everytime map is moved or zoomed based on viewport and zoom level. I got it working with code below, ...
3
votes
2answers
554 views

Assigning RouteIDs to polyline feature class in ArcGIS Linear referencing?

I have a Linear Referencing Route System in ArcGIS Geodatabase format (polylines with M values) and a separate polyline feature class of short segments (called TMC) that do not have RouteIds currently....
3
votes
1answer
1k views

Openlayers Add features performance for 3000 lines

We would like to implement the function of Addfeature in openlayers to draw lines and push them onto a vector layer, and overlay this layer onto open street map or google map. Those lines are draw ...
3
votes
1answer
4k views

Reproject a vector layer (EPSG:27700) using WFS onto a googlemaps background (EPSG:900913)

I have the following HTML-javascript code and i have problems reprojecting the vector layer (WFS) from EPSG:27700 (British National Grid) to EPSG:900913 (googlemaps). I managed to project the WMS ...
3
votes
1answer
78 views

How can I merge two adjacent polygons which borders are not touching each other

I want to merge adjacent single polygons which are apart from each other. Important note: I cannot use ArcGIS, I need to do this programatically, in any language (R, Python, Ruby, PostGIS) doesn't ...
3
votes
1answer
36 views

List group of line segments that are not connected to any other lines

In the image below, the system of lines includes 6 segments. This connectivity gives the appearance of an "island" as the internal segments are connected to each other and are not to the outside world....
3
votes
3answers
69 views

Projection offset between layers: OSM, GeoJSON

Don't know why there is an offset: The coordinates of the points that appear on the example were gotten through google's geocoder from some Rosario, Argentina directions. I have checked the lats and ...
3
votes
1answer
57 views

Polygon made by colour difference

I need to analyze differences (historical) in coverage of some species (seagrass Posidonia). Although its a marine species, subject area is very shallow and even from common satellite and aerial ...