QGIS is a cross-platform GIS application licensed under the GNU General Public License.

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3answers
330 views

How do I use SQL in the field calculator to populate a new column?

Courtesy of Geofabrik I have a "places" point shapefile which includes in the attribute table a column named "type". As can be seen in the attached image the column contains fields such as "city", "...
3
votes
1answer
499 views

How to count and rasterize polygon overlaps in QGIS?

I have a large number of polygons that are overlapping. I'd like to create a heat map and plan on using raster calculation to do this. My plan: to give each polygon a raster value of 1, and adding ...
7
votes
2answers
567 views

How to load a raster layer at the top of the QGIS ToC?

The following code inserts my new_layer just above the active layer in the QGIS ToC. new_layer = iface.addRasterLayer(...) Instead, I'd like my new_layer to be inserted at the top of the QGIS ToC. ...
3
votes
1answer
57 views

Is there a way to force QGIS to use scaleable markers for map prints?

The implementation of scaleable vector graphs in QGIS is very cool, however, when svgs are used for point pattern fill of polygons, these markers are obviously rasterized, blowing up the filesize of ...
1
vote
1answer
257 views

How to create path based on waypoints?

I am trying to map flight paths and compare historic paths with current ones (so I later need to perform some calculations as distances between them). For this task I am using QGIS on OSX 10.9.1 As ...
1
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1answer
69 views

Using QGIS, features are suddenly placed 7.5 thousand kms off correct location

I've been counting an muskrat dens on lakes with aerial photos by creating a feature in a separate shapefile. I checked my progress after doing about 80 small lakes and suddenly, half of the lakes ...
3
votes
2answers
227 views

How to edit overlapping lines?

I am trying to edit bus routes in QGIS. Multiple bus routes can run on the same street. When I want to change one bus route, I select one of them, then I enable editing mode. With the Node tool, I ...
2
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1answer
122 views

How to know the date when an image has been capturing on Google Hybrid QGIS?

How can I know precisly the date of different Google Hybrid pictures used in my project in QGIS?
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0answers
119 views

How to get the color of a vector layer in pyQGIS?

I have see this topic (How to change the color of a vector layer in pyQGIS?) but I'm looking for get the color not to change. How I can resolve my problem ? Thanks
2
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1answer
1k views

How to make GRASS and SAGA tools capable to use in QGIS?

I installed QGIS, GRASS and GDAL by OSGeo4w package, and as I finish the installation, I want to use GRASS tool, I face this problem: But I already installed GRASS and SAGA, how to make those tools ...
6
votes
1answer
2k views

QGIS python - identify and highlight features programatically

In QGIS there is an option to select features of a selected layer using a "identify feature" tool. Then the feature get highlighted in a different color and attribute dialog is poping up. like that i ...
7
votes
1answer
4k views

How to draw polygons from the python console?

I've been visiting and revisiting the page on geometry handling in the PyQGIS Cookbook: https://www.qgis.org/en/docs/pyqgis_developer_cookbook/geometry.html but can't seem to figure out how to get the ...
2
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0answers
111 views

QGIS: rotatable markers with offset from point

Im wondering, if its possible (in QGIS), to set a rotatable marker with offset from point, like in my example below. Any suggestion?
0
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1answer
300 views

Get list of CRS in QGIS by python?

It is possible to get list/dictionary of "Recently used coordinate reference system" from QGIS by python? Or get list of all "Coordinate reference systems of the world" also from QGIS by python.
0
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0answers
369 views

QGIS, how to change the centre point of a global map?

I have two global maps I want to show on one map in Qgis, however they each have different centre points, i.e. in one the atlantic is in the centre, and in the other the pacific is. How do I get them ...
1
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1answer
312 views

Problem with import CSV files to QGIS 2.0.1

I have a problem with import CSV files to QGIS 2.0.1. I have a file with WGS84 coordinates it looks that: Nr;Longitude;Latitude 1;18,06,23.66;54,83,12.50 2;18,08,81.30;54,73,09.30 3;18,23,47.62;54,83,...
3
votes
1answer
349 views

How to programmatically set a rule-based renderer in QGIS?

These days im in a process of developing a plugin , which highlights/change color of set of features in a vector layer depending on some calculation. i found nice article about QGIS – Rule based ...
0
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0answers
21 views

Why cant i buffer vector points imported from csv? [duplicate]

I ve imported a csv file with adresses of stores in longitude and latitude. I ve saved it as a shapefile and i can see the points on a map. Now i m trying to buffer the points to end up with ...
2
votes
1answer
705 views

How to select polygons by distance to a single polygon in another layer?

I have a shapefile A with a group of polygons, lakes. Now I want to select the polygons(lakes) that are within a specific distance to a polygon in a second shapefile, B, with the polygon a city. In ...
1
vote
1answer
169 views

How to install QGIS 2.0 on Ubuntu 13.10?

How can I install new version of QGIS (2.0)? When I try with the indication of the official web site of qgis, terminal write me that the last version of qgis (1.7.5 wrowclaw) has several plugins that ...
4
votes
2answers
927 views

How to get the file paths of the loaded layers in a QGIS plugin?

I am very new to GIS, QGIS and Python so please bear with me. I am using QGIS 2.0 and I would like to develop a QGIS plugin that would display the raster layers of the main window in order to allow ...
0
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2answers
58 views

How to get rid of artefact rectangles in QGIS Print Composer?

when inserting a map on the canvas of print composer and moving that map around, quite often, there is a rectangle that cannot be deleted. This rectangle is positioned at the initial place, where I ...
4
votes
2answers
5k views

How to perform SQL queries and get results from QGIS python console?

I'm writing a python script using QGIS API. I have to get results from postgres database table. The table has geometry field and other non-geometry fields. I want to perform SQL queries on non-...
3
votes
1answer
437 views

Get geometry column back when counting points in polygon using PostGIS

I have two PostGIS tables: earthquakes and borders, which contain point data on earthquake locations, and polygons of countries in the world respectively. I want to try and count the earthquakes ...
2
votes
2answers
2k views

How to resize symbols in the QGIS Print Composer legend?

I am trying to map a count data type via graduated symbol against a chloropleth and the legend is too big. The circles of the graduated symbols are the actual size of their corresponding values in ...
1
vote
1answer
141 views

Problems with connecting QDateEdit and QTimeEdit widgets to corresponding Field in QGIS Layer (shp/spatialite)

Could anybody give me a hint how to connect the QDateEdit and the QTimeEdit widgets with a field in a QGIS layer (shp or spatialite). The fields in the QGIS layers are from datatype "date" (dd.MM.yyyy)...
1
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1answer
62 views

Problem with QGIS unable to access virtual drive

After a motherboard failure I have had to reinstall QGIS Dufour on a Windows 7 laptop. As I share data with a desktop machine I use LiveDrive briefcase as a virtual drive. With all versions of QGIS I ...
0
votes
1answer
354 views

Polygonize(raster to vector) [closed]

I have been install QGIS 2.0.1.when I use Polygonize (Raster to vector)for convert jpg to shp I get error message such as: C:\windows\123.exe is not recognized as an internal or external command,...
2
votes
2answers
2k views

How to limit decimal places of coordinate values in GEOJSON file using QGIS 2.0.1-Dufour

Using "QGIS 2.0.1-Dufour", I try to convert a vector layer into GEOJSON file using "Save As" sub menu. I get the GEOJSON file, but the coordinates of points have values up to 15 decimal places. How ...
1
vote
2answers
469 views

Draw great circle rays from a single point along specific directions

How can I draw great circle rays starting from a single given point P (for example, from coordinate [34 N, 116 W] in this map) and along directions D1, D2, ... (for example, 30, 45 and 135 degrees) in ...
7
votes
1answer
542 views

How can I get Google Fusion Tables to work in QGIS?

I am using GDAL/OGR 1.10 and QGIS 2.0.1. I am trying to load a google fusion table into QGIS using the method mentioned in this blog post. The only difference is that I am not declaring a email and ...
1
vote
1answer
136 views

How does the tolerance influence QgsGraphBuilder and tieing of points?

I am developing a script which uses OpenStreetMap data to calculate the distance (over the road network) between each building and the nearest hospital. To do this, I mainly follow the official ...
2
votes
1answer
557 views

How do I set the projection and coordinate system for a TIFF file?

I have a topographic map of California (obtained from CAL-Atlas) as a TIFF file. I tried importing it into QGis, but it displays the map using a pixel based coordinate system rather than latitude/...
7
votes
3answers
1k views

How to count the number of lines connected to a point?

I have a water network which and I need to install elbows and Tees (T). When 2 lines connect to a point, I want to install an elbow, when 3 lines connect, I want to install a Tee. How do I get ...
2
votes
2answers
401 views

Terrain Accessibility map using GIS (ArcGIS or QGIS)

I need to make an accessibility map showing the walking distance based on the terrain and availability of road networks, could anyone point me in the right direction where i could learn to do so. ...
1
vote
1answer
818 views

How to find the polygons bordering a feature programmatically with qgis?

Is there a way to calculate the neighbors of a polygon with pyqgis for every feature? For example, the selected polygons relative to the one in the center: I found this solution, but it's a year ...
3
votes
3answers
307 views

keeping track of edited features QGIS

Does anyone know of a way to keep track of last added or edited features in QGIS? A kind of Editor Tracking tool.
0
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1answer
928 views

Custom forms and Python logic: attribute error [closed]

As a beginner to Python, PyQt4, AND QGIS, I am attempting to work with the custom forms feature in QGIS. At this point I'm not sure if my error comes from the code or the .ui. This blog gave me a ...
1
vote
1answer
64 views

How to automatically add identical new polygons to a layer?

I am seeking a way, using QGIS, to automatically add polygon features identical to others on the layer. In this case, they are water valves on a water network. Anyone know of a user-friendly way to ...
4
votes
2answers
1k views

Create A Maximum-Value Composite QGIS

I am looking to create a Maximum-Value Composite raster in QGIS I have three raster images: Oct 2012 Nov 2012 Dec 2012 All are in TIFF Format, Float32, EPSG:4326 - WGS 84 I want to stack these ...
0
votes
1answer
280 views

Why doesnt QGIS show the results from a WFS BBOX from a python script

I'm trying to figure out how to do get requests in QGIS using a bbox. I can get a bbox to clip a layer when I paste my uri into a browser but the EXACT same uri returns an empty layer in QGIS. A ...
0
votes
0answers
45 views

QGIS layer only displays when I uncheck on-the-fly transformation

I have a layer that covers the stats of Indiana that has the following Layer SRS: +proj=utm +zone=16 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs It will not display unless I uncheck the on-...
4
votes
2answers
746 views

How to compute area in acres in QGIS?

I am new to QGIS. I am creating a shapefile that will have several polygons. I need to have a column in the attribute table that will show the acres of each polygon. I have successfully done this but ...
2
votes
1answer
280 views

How can i add a north arrow in QgsComposition?

I'm trying to add an svg image of north arrow in QgsComposition using this code: mapRenderer = iface.mapCanvas().mapRenderer() theComposition = QgsComposition(mapRenderer) theComposition.setPlotStyle(...
3
votes
2answers
1k views

Creating square buffer in qgis

How can I create a buffer with square ends along a line segment in qgis? I've buffered lines using v.buffer in the GRASS plugin, but the -c option for square ends is not exposed in that interface. ...
1
vote
1answer
41 views

Plugins to guide inexperienced users: updating shapefiles and managing data

I am attempting to find a way to block adding features while certain attributes are not yet added. This would be useful in order to guide inexperienced clients and employees with the process of adding ...
0
votes
2answers
385 views

Latlng to UTM conversion with forced zone

I'm trying to convert a set of latlng coords to UTM but the points in the set are across two different UTM zones, 32T and 33T. This causes two near points like 44.51601173544275, 11.992860160820502 ...
1
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0answers
66 views

How to create a 1:n join and concatenate text attributes?

I have 2 polygon layers A and B. I would like to join the attributes from B into A for all the polygons from B that intersect A and for text attributes, i would like them concatenate. But apparently "...
0
votes
1answer
316 views

Automatically insert file path in QGIS table

I'm using R to create some plots that refer to specific values of some point in QGIS. Each plot is saved into a directory and for each point in QGIS I added a column with the path to the file. I know ...
0
votes
1answer
1k views

How to disable the Escape key for a dialog? [closed]

I may have found the solution to my own question but I have another problem. It turns out that the user can just hit "Esc" and close the form. How can I disable the escape key? I'm looking for some ...