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

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39 views

how to add vectorlayer in a mapcanvas with a raster

I am working in c++/qt4.8.5 with qgis api 2.8.2 For my application I had to load a raster in a mapcanvas, then with different action I had to add pint , line or polygon Is there a simply way to do ...
1
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0answers
133 views

QGIS Intersect returns empty layer

I'm following these instructions from the FCC: https://transition.fcc.gov/form477/Geo/finding_census_blocks_in_qgis.pdf Everything works just fine up until step #6, where the Intersect tool is used. ...
2
votes
1answer
99 views

How to get the center line between two linestrings

Where is the track of a ship when it is shipping always in the center of the English Channel between the coasts of Great Britain and France? I started with 2 linestrings and I created a lot of ...
1
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0answers
72 views

Spatial correlation using QGIS?

I'm looking into performing a spatial correlation test of 2 matrices to see where they overlay. To do so I need to create a grid layer of 2.2km2 around the coordinate points. I've tried the vector - ...
1
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1answer
53 views

I am using QGIS 2.6.1 but i dont know how to split a state into two states? [closed]

I have a .shp file of the states but my file is older one and after that one state in India converted into two different states so how can I separately show both the states on the map using QGIS. I ...
2
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1answer
354 views

Shapefile/vector layer not appearing in QGIS

I have a shapefile (calling it 'new.shp' for discussion's sake) that won't show up with other layers. If a fresh file is started and I bring in new.shp, it will appear, but any other layers imported ...
3
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1answer
474 views

Using GPS tracking with QGIS and Panasonic Toughpad

I'm using QGIS with a Panasonic Toughpad FZ-M1 with inbuilt dedicated GPS. I can connect okay to the GPS using View --> Panels --> GPS information. Satellites and signal strength show up, but no GPS ...
2
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1answer
143 views

Problem with Distance Matrix in Qgis 2.83

I want to calculate the distance of archaeological sites to the nearest river. Following this question Calculating the minimum distance between points and polygons in QGIS I extracted the nodes of ...
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1answer
39 views

Query across layers of SHP files?

I would like to query features from a SHP vector that intersect with features from another vector. Pseudocode: "Name" IS intersects( countries) How would be the valid query composed?
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2answers
35 views

Putting result of selection of plots in frame of QGIS?

I have made a plugin for QGIS in pyQt. Then I can make a query from a PostGIS database and I get the plot or bunch or plots results of that query in a layer. This layer is overlapped on the top of a ...
2
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0answers
56 views

How to copy elements and attributes?

I need to copy many elements (and their attributes) from a shape file and paste to another one. If I use copy/paste functions it paste only the polygons but not the attributes, How can I solve it?
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1answer
72 views

How to re-render only a single layer on a mapcanvas?

In my application I have a mapcanvas that contains several layers. some of layers need to be updated or rendered again because data has been changed ( like the geometry or some attributes ) Is there ...
2
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1answer
76 views

pyqgis traversing subgroups and group layers

I am trying to find the name of subgroups using pyqgis. I have been trying to use Playing with subgroups I am however unable to traverse and get the names of the subgroup. I have tried the code on ...
2
votes
1answer
418 views

How connect points with lines in QGIS?

I need to connect points with lines in QGIS. I am in this fresh out so I'm not sure how to do it and I need a little bit help with this. I read several posts i and tried to do something about it but ...
1
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0answers
100 views

WKID issue when adding raster layer from ArcGIS “mapserver” to QGIS via REST

QGIS docs here describe how to do this. I am trying to add a layer from this MapServer: gps.digimap.gg/arcgis/rest/services/JerseyBaseMap/MapServer When I try the following command from the Python ...
2
votes
1answer
159 views

Grid or True North In QGIS

With Qgis general settings and changing nothing on the preferences window, which north system (true north or grid north) will be activated ? Would it be determined by selection datum, for instance ...
3
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1answer
284 views

D3 javascript and GeoJSON: lines in Stockholm map very strange

All the code and shapefiles that I'm using are available in this GitHub repo. I'm trying to draw a map of Stockholm with D3. The shapefile looks ok in QGIS: However, drawing the GeoJSON produces ...
3
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2answers
153 views

pyqgis add a picture

I am looking for a way to add a picture to my map using pyqgis. Are there any examples of how to do this. I know it can be done using the classQgsComposerPicture. I am not much of a programmer so I ...
3
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0answers
70 views

How to calculate the area within a 4m clipped buffer derived from a raster

I am using QGIS 2.8.3. I started by classifying my area into habitat types using the semi-automatic classification plugin (SCP). Then I added points, and a 4m buffer around the points. So I could then ...
3
votes
1answer
87 views

When creating an expression in QGIS, is there a way to reference the next record and previous record?

I have a set of points from a GPX file, and would like to create a heatmap from them, with the points weighted on the amount of time spent at that point. I want to create a calculated field in QGIS, ...
2
votes
2answers
105 views

Problems installing QGIS on Windows Vista

I have tried several times on several windows vista machines to install QGIS (both versions 2.10.1 and 2.8) but with no luck. It seems to install fine without any errors but when the installation is ...
3
votes
1answer
372 views

cannot convert shapefile into GeoJSON

I have downloaded a shapefile of Stockholm (files on GitHub). I'm trying to convert the shapefiles to GeoJSON with the ogr2ogr command line tool. It does not work with the following error: Export ...
1
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1answer
92 views

Can I get rid of the borders around the colour boxes in QGIS Print Composer Legends?

If you look closely at a legend in the QGIS Print Composer, you'll see that each colour box has a hairline (1 px) border. How can I remove these borders? By playing around with the settings, I've ...
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0answers
19 views

Expression geomnearest not found

I have been making some new printer composers in a project I am working on in QGIS. I had implemented the use of expressions to create content for the title block, one of these is the geomnearest ...
1
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1answer
289 views

Delete (don't hide) text annotations in QGIS

I feel like this question should have a really simple answer, but I can't find it anywhere. I added an annotation to my map while experimenting with different buttons, and it wasn't at all what I ...
1
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1answer
173 views

Move feature in front

Is it possible to move feature in front of another? If I have smaller polygon and I draw larger polygon over it, is there a way how to move the smaller one in front? Is it possible in QGIS or better ...
2
votes
1answer
123 views

How to update a postgres/postgis table periodically with multiple data?

I have created a postgis table from point.shp with 5 fields containing 20 records. Now I want to populate the table with another 150 records keeping the previous 20 records so that the total records ...
1
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1answer
81 views

QGIS delimited text import CRS not being defined

I've recently updated to both the long term release and 2.10 versions of QGIS and the delimited text plugin has stopped working. Everytime I try to add a CSV file and say ok on the plugin it no ...
2
votes
1answer
81 views

Exporting only certain fields from a PostGIS table using QGIS Python

I'm trying to export tables from a PostGIS database into MapInfo TAB files, but only certain rows and columns. I have my rows exporting right, using a query, but I'm stuck on just getting the columns ...
1
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1answer
42 views

No export dialog on QGIS 2.8 and 2.10 with Mac OS X Yosemite?

I'm trying to work out the map making tutorial here: http://www.qgistutorials.com/en/docs/making_a_map.html When I try to export an image or pdf or even print the map I built in the composer, I ...
1
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1answer
54 views

2.10 program group option to open QGIS with GRASS

I have installed QGIS 2.10 on Windows 8. I cannot find the 'option' to start QGIS with GRASS - as has been previously answered. Have I possibly missed something in the install? Is this 'missing' ...
3
votes
1answer
58 views

Display or export gdal_translate exponential scaling equation

I have an GeoTiff raster that contains elevation information at each pixel. As OpenLayers 2 can't display GeoTiff, I convert it to a PNG image and have to apply an exponential scale so the resulting ...
2
votes
1answer
56 views

Plotting points on a map based on address text string of location

This may be a naive question, but I'll try anyway. I am working in QGIS, and I have a shape file with more than 2000 rows containing information about specific trees in a botanical garden; their ...
1
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0answers
15 views

Project do not open anymore because of a minidump [duplicate]

I have closed my project two days ago and this message appeared : minidump déposé dans C:\Users\wwf-adm\AppData\Local\Temp\qgis-20150903-171144-3780-1392-8fdd08a.dmp When I try to open my project, I ...
1
vote
1answer
81 views

Problem creating polygon in a layer

I am working in c++ qt4.8.5 and api qgis 2.8.2 c++. In my application I had to put polygon to define attractive zone. I found a great post in stackexchange (86812). I have based my on this post and on ...
3
votes
1answer
209 views

How to fix QGIS Plugins crashing with “NameError: name 'pyplugin_installer' is not defined”?

I recently switched to Windows 10 and therefor did a clean Windows and QGIS 2.10.1 Install. QGIS worked fine, I reinstalled all Plugins, that I used to have. No Problems. Today I switched on the PC ...
3
votes
1answer
128 views

Tilted projection in QGIS

I'm trying to add tpers projection as a custom projection in QGIS 2.10.1 In the Custom crs dialog I'm adding the proj.4 text: +proj=tpers +h=500000000 +lat_0=19 +lon_0=99 +x_0=0 +y_0=0 +a=6371000 ...
1
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0answers
38 views

How to best populate points within a polygon with a set of rules

I've got a polygon (a Circle) with a certain size. I want to put points inside it, as much as I can, but with a set of rules : Points can't be near each other, up to 500 meters. Points can't be near ...
1
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2answers
70 views

QGIS Processing Plugin Not Loading “RuntimeError: maximum recursion depth exceeded in cmp”

I am having serious issues with my QGIS program regarding the Processing Plugin. Upon start-up and if I turn on the plugin within the program. I have uninstalled and reinstalled the program. Have ...
1
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1answer
223 views

QGIS Generating a Lat/Long Degree Grid in Composer

I made a map in WGS84, which is positioned and referenced correctly. Now I loaded the map into the Composer and added a grid, with horizontal and vertical lines each 500 world units (m). When I ...
6
votes
2answers
289 views

How can I average point features spatially in QGIS?

I have a GPX file with track points and I want to average the points spatially to improve accuracy of the point feature. I can't just make a polygon and find its centroid as the number of overlapping ...
1
vote
1answer
53 views

How to create a specific svg file with data from a feature

I am working in c++/ QT4.8.5, with qgis api c++ 2.8.2 I have to display a dynamic icon for a feature. some of the data change periodically and in order to display the change i need a svg that can get ...
3
votes
1answer
96 views

QgsExpression using complex sql and python subsitution

I have a sql statement i am running in postgres fine and would like to transfer it to a QgsExpression mainly because I have loaded the layer in Qgis. My sql is: select column a,column b from table1 ...
0
votes
0answers
12 views

Tracing a raster layer in QGIS [duplicate]

I have a basic map I would like to trace into vector form in QGIS. The map is just a JPEG and has no coordinate reference data. Whenever I import it into QGIS, it ends up as a tiny speck at 0,0. How ...
0
votes
1answer
115 views

Qgis 2.10 unable to add a new feature in spatialite via sql function “GeomFromText”

Using Python code in my plugin the function in sql language "GeomFromText(POINT(X Y))" gives the following error: "OperationalError: no such function: GeomFromText" Plugin functions in previous ...
1
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2answers
92 views

Syntax error in parameter formula of field calculator funtion

I'm using a QGIS 2.8.1 in windows. Have some doubts with syntax when use string in python console. I want to use the field calculator funtion like: processing.runalg('qgis:fieldcalculator', input, ...
0
votes
1answer
60 views

messed up shapefile attribute table text

I have a .shp file from AutoCad imported to QGIS (using _MAPEXPORT > text in AutoCad) and this is what happens to text in attribute table - example: {\Fsimplex|c0;O\Fsimplex|c238;Š\Fsimplex|c0; ...
4
votes
1answer
263 views

Exporting Contours from QGIS into AutoCAD [duplicate]

I'm trying to export contour lines from QGIS into standard AutoCAD but I'm not having much luck. It does not seem to matter what type of file I select as the output during the contour creating (eg. ...
2
votes
1answer
50 views

How to reduce points by proximity

I got a layer with over 4 million points. The distance between the points are 1 meter. How can i reduce the data so that no points have less than e.g. 10 meters between them?
1
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0answers
72 views

Polygons within Polygons Spatial Analysis

I have a polygon layer of planning applications and I am wondering if anyone can give any advice and or has seen or written a blog post that might point me in the direction of creating relationships ...