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

learn more… | top users | synonyms (1)

1
vote
3answers
205 views

How to prepare a multi-colored vector layer?

I need to present a multi-colored vector layer and something similar to below: I need to prepare the vector layer by making use with the data set available in my database. Inside my database, I ...
1
vote
1answer
97 views

Analyzing Raster Data From Vector Layer Buffer

I am using QGIS 2.0. I have satellite images of night-time lights all over earth. I also have a vector shapefile of country boundaries including the largest cities on earth. I want to use buffers to ...
1
vote
1answer
65 views

Calculate 2D line of site from line layer and polygon layer using ArcGIS 10

I'm trying to run an analysis where I need to clip a radiating lines layer by land features to get the maximum distance from the central point to the nearest obstacle. What I have is a large line ...
2
votes
3answers
214 views

How to get a bbox selection of huge shapefile as GeoJSON?

I have a 4.29 GB Shapefile from which I want to extract features as GeoJSON, defined by a bounding box. This should be as fast as possible, because I want to use it in a web application. My first ...
4
votes
1answer
88 views

Simple way to compare ranges and distributions of species, looking for correlation and differences between ranges

As a biology student just beginning with GIS, wondered if someone could give me an idea of what tools to go about using to compare the range of 3 species that have trophic effects on one another. I ...
3
votes
1answer
114 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
2answers
294 views

Is there a vector affine transformation tool in QGIS2?

In QGIS 1.8, I can transform my point layer with the plugin "Affine transformation". So, this plugin don't exist in QGIS 2.0. Do you know a method to simply translate (i.e : X -> X+30000) in QGIS 2 ? ...
4
votes
1answer
168 views

How to horizontally align irregularly shaped point symbol to vector layer in QGIS?

Fairly new to QGIS and searching a method to graphically align my point symbols in the direction of the vector. The symbol represents a water valve in an irregular shape in close proximity to a vector ...
2
votes
1answer
115 views

Handle a great amount of Markers with OpenLayers

My general Problem is to maintain a lot of markers. For the beginning I want to display all Bus Stops of Berlin, Germany and surroundings as Markers. I already got that I have to use a strategy like ...
1
vote
1answer
90 views

cannot click on points in openlayers

I use openlayers 2.13.1 along with Geoserver and PostgreSQL I have a code for a vector layer , in my openlayers like so //style for layer var style_d = new OpenLayers.Style({ 'fillColor': ...
2
votes
1answer
143 views

graduated labels in QGIS

I've searched on Google but haven't found an answer. The QGIS Dufour GIS provide an enhanced vector-styling interface but is it also possible to graduate the labels like it is possible for the ...
0
votes
1answer
836 views

Draw order (zIndex) of OpenLayers polygons and points in the same layer

My question is similar but slightly different from this one: http://stackoverflow.com/questions/5003349/openlayers-vector-features-z-indexing I have an OpenLayers Vector layer which contains polygons ...
2
votes
1answer
296 views

Creating buffers that will not overlap in QGIS

I am dealing with a .shp with a number of points in it. The distances between points range from ~300m to 5km. I wish to create a 1 km buffer around each point with as little overlap as possible. Each ...
2
votes
0answers
156 views

QGIS: How to reverse vertex ordering in polygons

I am working with an Oracle spatial connection in QGIS through which I am accessing and editing a vector layer. I find that when I edit a geometry, the vertex ordering is reversed (to clockwise in the ...
2
votes
3answers
189 views

Generating a polygon tile index from multiple vector datasets

OK. well this is silly, in that there is no way it should be as difficult as it has been for me to find information regarding how to generate a polygon tile index from multiple vector (contour) tiles. ...
0
votes
0answers
209 views

How Can i create a Vector layer from selected features qgis

In my qgis plugin i select dynamically features from a Vector layer. and currently i create a new layer from selection on combining all feature into a new feature: theField = QgsField self.theString ...
0
votes
0answers
137 views

how do I add attribute features to an attribute table which already exists?

Using Verson 2.0, downloaded as normal. I have an ESRI shapefile of my road map for 2006. I have a paper map of roads for 1969. I want to see what roads have been built between 1969 and 2006 (none ...
4
votes
1answer
420 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
247 views

Comparing 2 polygon shapefiles for differences [duplicate]

I have 7 shapefiles, each representing a year, all containing lots of polygons (c. 500,000). My aim is to take any 2 of them and compare how they have changed in terms of size and shape of polygon. (i ...
4
votes
1answer
124 views

Suggestions for vector format for contour map

I've been trying to create a contour map of a DEM and I've been running into some technical problems. I want to avoid artifacts, so I'm using a DEM of the entire area. This means the size is rather ...
0
votes
0answers
76 views

Calculating vector statistics in GRASS

I have a points layer, each of points have an year attribute and I want to count how many points in each year. I use GRASS-GIS and its v.univar function: v.univar -e map=mod14_hmao column=year ...
1
vote
1answer
105 views

OpenLayers, Get clustered point's val

I'm working on a map with WMS overlays and a lot of markers, my problem is when I try to calculate the average of points clustered, I've found how to differentiate the behaviour and the label text ...
2
votes
1answer
3k views

OpenLayers Vector Layers: adding and removing features VS. redraw/refresh

I am currently using addFeatures and removeAllFeatures in my code to get the desired results and this is working OK. However, I have been asked to ensure that the vector layers are not being ...
1
vote
2answers
262 views

Splitting discontiguous vector feature in QGIS

I'm a QGIS novice. I'm trying to correct a map of Europe in QGIS, and it's incorrectly assigned Corsica to Germany. I can't seem to split Corsica off of Germany because when I use "split features" to ...
1
vote
1answer
3k 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 ...
2
votes
3answers
421 views

Ordnance Survey 1 km Grid

I am wanting to get a copy of the OS 1km Grid layer. I have found these previous questions: Ordnance Survey grids - download or generate? and Ordnance Survey Grids But neither provide the ...
4
votes
1answer
382 views

Loading a multipoint shapefile in R

This issue has only been raised in the community once, two years ago, to the best of my knowledge. I think it's high time to raise the issue again! readOGR, from the rgdal package, cannot handle ...
0
votes
2answers
558 views

How to Resolve Inconsistent OpenLayers vector position Over Google map [duplicate]

I have an OpenLayers map with a Google base layer and an OpenLayers vector layer on which people can draw their own bounding boxes using the DrawFeature control. I have found that, as you zoom in, ...
6
votes
2answers
516 views

Convert points to lines with Python GDAL

I have a dictionary with points. The points are derived from a raster (see image below). The points are not sorted and are not in order. The dictionary looks for example like this: pointDict = {0: ...
4
votes
2answers
172 views

Problem overlapping shapefile and vector in R

I want to plot a shapefile over a raster file in R but I can't make them overlap perfectly: the raster appears to be rotated of few degrees counter-clockwise. Is it a problem with the projection? ...
1
vote
1answer
236 views

Openlayers Vector Event Popup with Textbox

The Openlayers map here: http://www.dassh.ac.uk/demonstrations/valmer/demo5.html has an event to add a vector layer, plus creates a textbox on the page below. Ideally I'd like the click event to add ...
-1
votes
1answer
1k views

Retrive data from database in openlayer GIS

i am using this code but it shows nothing, whats wrong with this code. <!DOCTYPE html> <html lang='en'> <?php $conn_string = "host=localhost dbname=postgis_21 user=postgres ...
4
votes
1answer
613 views

GDAL polygonize lines

I have a raster file containing roads (left image). I polygonize the raster file with GDAL (see the script below). In the end I like to have vector lines. However GDAL only gives me something like ...
5
votes
0answers
149 views

Convert Graphics to Vector in QGIS

I am wondering if there is a way to convert a graphic produced from symbology in QGIS to a vector layer (ie: shapefile). I have a point layer with bearing direction in the attribute table. Following ...
0
votes
0answers
225 views

How to convert Raster to points in MapInfo?

I wanted to convert Raster data to point data in MapInfo.Does there any tool to convert? can anyone help me?
1
vote
1answer
85 views

Raster Data to Polygon [closed]

I need to "translate" raster information to a set of polygons. The raster to polygon tool will not work. I created a fishnet with the same resolution of the raster and converted it to polygons. I now ...
1
vote
1answer
399 views

Openlayers Vector Layers eventListeners: how to specify different data without defining multiple layers

I have a map. It has two origins, and two destinations. The code for one origin is here: vectors_origin = new OpenLayers.Layer.Vector("Origin", { eventListeners:{ ...
8
votes
3answers
543 views

Create interactive map with no server

I have managed to build a great web mapping application using tiles created from GeoWebCache and a custom gridset, but I now need to add an overlay to the base maps. The only interactivity I need is a ...
2
votes
1answer
315 views

How to change layer transparency without changing border lines?

I have a raster image of elevations. I have added a vector shapefile that contains local political divisions. I want to keep the elevation colors, but I want to keep the black lines representing the ...
1
vote
1answer
61 views

Decoding Mapbox grid response

Can anybody give me insight into the grid json structure that Mapbox returns for use with overlays on tiles. What is the significance of !,#,$? Thanks in advance.
0
votes
2answers
850 views

Using OS Mastermap SLDs in QGIS

In an answer to a question asked by @Canningmister, @tjmgis posted an excellent answer Styling OS Vectormap Local in QGIS? about making OS SLD files work in QGIS. As an amateur user who uses QGIS to ...
1
vote
0answers
68 views

How to auto-fill a new point vector in a vector layer?

When I work in-situ I manually add points in my shape-file. I would like that when I add a new point some attributes would already filled with values calculated programmatically. E.g in my first ...
3
votes
4answers
408 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 ...
2
votes
1answer
343 views

pyQgis in stand alone script, vector loading error

I am trying to use the Qgis functions in a stand alone Python script. I m running Mountain Lion OS, 2.7 Python & the Qgis 2.0.1 Dufour. My main problem is that I cannot get started - I cannot ...
1
vote
1answer
85 views

map can only have one feature, after user click

I'm using openLayers 2.13.1. I have a map wih a vector layer and Editing tools. I want the map to have only one feature even if the user keeps adding. So I want the new feature to automatically ...
1
vote
0answers
73 views

Problem in removing dangles in road network [closed]

Im using qgis2.0 , In a given road network i have to remove dangles, for that what should be the tolerance to be added generaly. please help me resolve this issue
0
votes
2answers
291 views

MapServer: How to display and style a Text layer?

I'm trying to display a text layer using MapServer, but I'm kind of confused how to get it to display properly. When opening the .TAB file in a GIS application (in this case, MapInfo Profressional) ...
7
votes
2answers
571 views

What does vector tiled map mean?

I'm working on an application that renders geoJSON into OpenLayers map. The idea is about not having PNG images downloaded from external services (OSM or Bing) but having geo information in geoJSON ...
1
vote
0answers
51 views

Delete polygon underlap?

I am editing a layer in QGIS with severe polygon overlaps. Is there a way to delete the underlapping portions (i.e. the invisible parts) using QGIS? If I import the layer into GRASS using the ...
1
vote
2answers
290 views

Decrease resolution of vector shapes (polygon) i.e. reduce size and number of points in outer ring

I'm trying to get a kmz export down to less than 3 megabytes and am wanting to do so by reducing the number of points in my polygons' outer rings. I've seen this concept in action when it comes to ...