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

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2
votes
1answer
26 views

Create points symbology with more than one parameter

In QGIS i would like to create symbology for points layer where the symbology will take into account more than one parameter (currently two). i.e.: My points layer has street names and house numbers ...
1
vote
1answer
341 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
303 views

How to create pop-ups with graphs on point layers?

i have a postgresql database which is refreshed all 10 minutes and i need to create graphs in pop-up with the data. When i click, a pop-up (or annotation ?) appears. How can i make it possible ? ...
4
votes
1answer
65 views

How can I create a QgsRubberBand with holes?

I tried to create a QgsRubberBand object with holes, but failed: rb = QgsRubberBand(iface.mapCanvas(),True) geom = QgsGeometry.fromWkt("POLYGON((0 0,4 0,4 3,0 3,0 0),(1 1,3 1,3 2,1 2,1 1))") ...
1
vote
0answers
14 views

How to refresh or update a vrt layer in Qgis?

When using the QGIS SpreadSheet Layers plugin, how do I update the SQLite query without closing and reopening QGIS? I cannot see a "watch file" equivalent. The plugin creates and uses a *.vrt file ...
2
votes
1answer
14 views

How to load stored composer from project file in standalone QGIS application?

I would like to load a .qgs file and get a composer from it, but I can't figure out how. Is there a way, or do I have to read the xml myself and individually set the appropriate values for the ...
9
votes
5answers
3k views

How to modify single Pixel values in QGIS?

I would like to modify a raster (pixel values) in QGIS. The plugins "value tools" can easily provide me with the value of the pixel of my raster. However I don't know how to modify it. I have found ...
0
votes
1answer
31 views

Point Sampler Python Error in QGIS?

I downloaded the point sampling tool for QGIS and I'm trying to run it. A few days ago it worked fine, but now it gives the following error: An error has occured while executing Python code: ...
1
vote
0answers
26 views

Remove inner rings from QgsGeometry polygon in QGIS Python

I am a QGIS python user. I want to iterate over the rings of a polygon to remove holes in the polygon, so: I need to iterate over the rings in a QgsGeometry polygon I need to detect the main ring ...
3
votes
0answers
64 views

How to develop a QGIS plugin to fully run spatial queries with PostGIS?

I am developing a QGIS plugin that fully runs spatial queries with PostGIS. I developed all spatial queries which need some adjustment. I am looking for some resources or documents to know how to ...
-1
votes
1answer
30 views

How to classify shapefile values in QGIS?

I would like to classify shapefile values using graduated style in QGIS, but instead of using the default mode of classification (e.g.natural breaks with values range 0-10, 10-20, 20-30), I would like ...
4
votes
5answers
134 views

GPS Track Editor to crop tracks with select by clicking start and end points

I'm trying to take a bunch of gps tracks of mountain bike rides and turn this in to a trail map. I want a single track for each trail. I'm looking for an editor that will allow me to select a ...
3
votes
2answers
66 views

Make a Qgis layer update from a changed data source

I'm trying to get layers to update automatically when their data source changes. I'm using R to write a shapefile with an attribute, and colouring according to that attribute in QGIS. I want to write ...
2
votes
1answer
32 views

How to launch Processing tool User Interface using PyQGIS?

I am trying to launch the UI of a processing algorithm using Python script but I cannot find a simple way for it (aside double clicking on it in the process toolbox of course). The plugin is a water ...
3
votes
2answers
608 views

How to customize the QGIS GUI using Python?

Is it possible to hide/remove/customize the default UI of QGIS from a Python plugin? I want to add my own menus and toolbars and remove some included by default in QGIS. If it's possible, which ...
2
votes
0answers
34 views

How to add a map created in QGIS to a Matlab plot

I am generating a number of plots in Matlab. I want to overlay these over maps I have created in QGIS. I thought the best way would be to import the maps as a geotiff into Matlab and then overlay my ...
0
votes
2answers
263 views

How to get image pop ups in QGIS?

I have a map of an area and georeferenced photos. I need to be able to bring the pictures as points and then be able to click at a certain point and an image pop up.
4
votes
2answers
1k views

How to automatically reload raster layers if source is changed in QGIS?

How to automatically reloaded raster layer if source is changed? (The path is the same but inside source file are changes) I use: qgis.utils.iface.mapCanvas().refresh() but layer not refresh. # ...
2
votes
1answer
158 views

How to print 2 maps in the same PDF page using PyQGIS?

I am trying to generate a one-page PDF document containing the following items: 1) On the left half, a full state map (say, New York State). 2) On the top right quadrant, a map that zooms in to one ...
1
vote
1answer
25 views

Align and reshape polygons based on surrounding polylines

I am trying to use a shapefile with polygons and I am trying to align it to a road network, that the polygons align themselves to surrounding streets. Is there a way to automatize alignments between ...
0
votes
0answers
19 views

Building Raster Attribute Table (RAT) in QGIS?

How can I build a Raster Attribute Table in QGIS 2.10 without using Python?
0
votes
1answer
31 views

Max Number of Feature Selection in ArcGIS and QGIS [on hold]

What are the limitations on the maximum number of features that you can select in ArcMap and QGIS?
0
votes
0answers
62 views

QGIS 2.8.1 crashes when connecting to Personal Geodatabase?

I have a problem connecting to a ESRI Personal Geodatabase. I used to be able to connect to the database using QGIS 2.6.1, but I did some editing to the database in Arc and after that I was unable to ...
1
vote
1answer
307 views

Adding MrSid to QGIS on Windows

I'm fairly new to QGIS and was hoping someone could help me load some MrSID photos into QGIS. I have read some posts and have installed the OSGEO4W Installer and selected the GDAL-MRSID Lib. I ...
1
vote
0answers
198 views

Load MrSID file in QGIS 2.2 on Ubuntu 13.10

Is there a way to do this? I have tried a number of the write ups on this, and it appears that libgdal-mrsid-src no longer exists. Is there any other workaround? USDA NAIP imagery is sent as MrSID.
0
votes
0answers
12 views

Module nziv not found in QGIS 2.10.1-Pisa

I want to use nviz in QGIS2.10.1-Pisa on windows 7 and I always get the same warning message : "Module nviz not found", whenever I click on it in the GRASS tools Modules list. I have tried to ...
0
votes
0answers
9 views

MrSID on QGIS 2.10 Ubuntu [duplicate]

i have Qgis 2.10.1 Pisa and GDAL 1.11.2, and i cant open MrSID (.sid) images en QGIS, i have lost three days trying to make it work, but i cant make it. My linux is 14.04 trusty tahr. Thanks ! ...
4
votes
3answers
643 views

How to find unique values of an attribute with python in qgis?

i look for solution to get the unique values of an attribute of a vector layer. what is the best way in python qgis to get the unique values of one distinct attribute? I work with qgis 1.8.0.
2
votes
1answer
128 views

QGIS 2.8 topological editing creating vertices

When using the node tool with topological editing enabled on a group of multiple lines, double clicking sometimes doesn't create new vertices. Instead, the line segment gets selected. When this ...
3
votes
4answers
1k views

Why do area calculations return negative values?

I have created a shapefile with some polygons and am now trying to calculate the area of these polygons. The original CRS was WGS84, I have reprojected it to WGS 84 / World Mercator so unit is metres. ...
0
votes
1answer
29 views

Is it possible to change the geometry without startEditing the layer

I am working in c++/QT 4.5 with the QGis 2.8.2 API. I had to change the geometry of features in a layer each second. Each second new data comes from the Ethernet connection, the application gets the ...
3
votes
4answers
1k views

Can I use QGIS with Qt5?

I want to use QGIS with Qt 5.But i don't know the exact relationship between Qt and QGIS.Will there some problems if i use qgis with qt5 or it will not depand on it...
2
votes
2answers
110 views

PostgreSQL trouble editing points / lines / polygons in QGIS

I have a problem with postgresql and QGIS : I can add points/lines/polygons and fillup field But I can't : delete points/lines/polygons modify points/lines/polygons (move or modify field) ex : ...
2
votes
4answers
312 views

How to convert a vector map to raster in Qgis?

I am creating a thematic map (vector data) with different classes. How to convert this vector map to a raster map, keeping the classification?
2
votes
0answers
16 views

What are the rendering options for timeline animations in QGIS?

I want to animate a shapefile that has a timeline (DATE) attribute using QGIS. The [TimeManager] plugin (http://anitagraser.com/projects/time-manager/) has been installed and provides sufficient ...
1
vote
1answer
13 views

How to add a point in a empty vetorLayer creadted in memory

I am working in c++/qt 4.5 and qgis api c++ 2.8.2 I had to create and empty vectorLayer and add Point I saw in the qgis cookbook that it is possible to create a vector layer in memory ,I did that, and ...
6
votes
2answers
82 views

How to bulk import gpx files to QGIS and merge into a single shapefile?

I am looking to create my own 'heatmap' of all the bike rides I have recorded using the app Strava in QGIS. I have over 450 individual gpx files and would like to merge the track points layers into ...
1
vote
2answers
56 views

How to show variable values in message bar in QGIS?

I know that I can write custom text to message bar with the QgsMessageBar.pushMessage() method. But if I understand the documentation right, there's no room for variables added to a string where they ...
-2
votes
0answers
18 views

what is the script for pdf file hyperlink for a diffrent polygon diffrent pdf in qgis [on hold]

what is the script for pdf file hyperlink for a diffrent polygon diffrent pdf in q gis.and whenever we open that file any computer that time they not say create again script and path.
1
vote
1answer
185 views

How to apply new WFS-Filter features like intersect

I was pleasantly surprised to find very much enlarged filter support in QGIS-Dev (1.9.0_Master). One application would be a WFS-Filter which combines $geometry and Intersect in order to load only the ...
1
vote
0answers
18 views

How to change programmatically the value of attribute in one of several feature in a vectorLayer

I have a vectorlayer that contains a lot of feature, I know that each feature has an unique Id Each of them has some propertie like coordinateX, coordinateY, color, name With a QTimer, each 2 sec I ...
1
vote
1answer
10 views

Building error on changegeometryvalues

I am working with c++/QT and c++api gqis 2.8.2 I want to change the geometry of a feature, I have this code : QgsVectorLayer * lLayer = mMapLayer.value(TRACKS); QgsVectorDataProvider * ...
2
votes
2answers
568 views

'QgsVectorDataProvider' object has no attribute 'select'

I want to create a tool layer in QGIS 2.4 that will select any vector features that intersect with that point. In my script I tried the following function: def selectFeature(self, point, button): ...
1
vote
1answer
16 views

How to register a broadcast on QGIS to start my plugin on start after loading plugins

I want to perform a default task when user opens QGIS but here I am building it as a python plugin so I want a signal or broadcast to call my plugin. I didn't build QGIS from source my plugin should ...
1
vote
0answers
15 views

problem with view of open layer plugin map and swiss national coordinate system in print composer

Mi projects are in the swiss coordinate system (CH0193+ / LV95) and I use Open Layers Plugin for the base map (google streets). In the normal window, this seems to work fine: As soon as I open ...
3
votes
3answers
1k views

How to extract X Y coordinates and RGB from pixels using python in QGIS?

I'm trying to white a Python plugin in QGIS (2.2) to get, for each pixel of a raster image, its X Y coordinates, as well as, its RGB (3 bands) values. At first I opened the raster file using: rlayer ...
1
vote
0answers
17 views

Output formats not showing in heatmap plugin (QGis 2.10.1 in ubuntu 14.04)

I just upgraded to QGIS 2.10 (using the debian repos) and the heatmap plugin doesn't show any formats in the dropdown menu. I'm able to open every raster format I have at hand and, of course, the ...
0
votes
1answer
22 views

Why doesn't fTools Line to Polygon work?

I am working new with QGIS (Version 2.8.2 / Window 8.2) and try to make Polygon from Line (see example picture 1) with the fTool LineToPolygon, but it doesn't work (see picture 2). I work with ...
0
votes
1answer
460 views

Can QGIS open a SDF file created by HEC RAS?

I used the "export GIS data" option in HEC RAS and got a SDF file. Is it possible to open it in QGIS?
1
vote
0answers
13 views

access the encrypted table in qgis

I have a vector layer in qgis connected to PostgreSQL database table. Suppose I encrypt the table column using pgp_sysm_encrypt or some other encryption in PostgreSQL Is there any way i can say ...