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

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3 views

Can I use the QGIS field calculator to populate foreign key on a child table based on querying nearest point?

I am using a PostgreSQL database in QGIS and I have two tables with a parent child relationship - table_Locality is parent and table_Surveypoint is child: table_Surveypoint has an empty column called ...
6
votes
2answers
259 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. ...
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1answer
24 views

How to create a text file containing layer names in QGIS?

My QGIS ToC contains layer groups and some layers that do not belong to any group. I would like to create a text file containing the name of those layers that do not belong to any group. Is there an ...
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0answers
50 views

Borderlines of states subdividing my GRID

![enter image description here][2]I just merged a map of a country with its states, so I went from having 1 feature (the whole country) to 32 features. Is there any way to have the borders of the ...
0
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1answer
74 views

How to know the real size of grid? [duplicate]

Im working with QGIS. When dividing a map with a grid I set in the paramters X=0.1 and Y=0.1. Could someone please explain what does that mean? I mean would the map be divided into 100mx100m squares? ...
0
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1answer
196 views

Polygon grid shape file for landmass

I am interested in generating a polygon grid shape file for the landmass of the world. What I have presently is two tables in postgreSQL. Table 1: Coastal area shapefile ...
1
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1answer
28 views

How to automatically create 10,000 sets of random points for further analysis in QGIS?

I'm using QGIS and would like to know if I can automate generating multiple sets of random points and mean distances? I have a data set consisting over 600 coordinate points for Mistletoe across ...
4
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4answers
3k views

Measuring the distance between lines and points in QGIS

Using QGIS - I have a vector of fault lines. I have point data in the form of a csv which I have also loaded into QGIS. I need to know how far each point is from the nearest fault line then enter ...
3
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1answer
30 views

How to display OSM relations (in QGIS) from osm2pgsql populated PostGIS DB

I have a PostGIS DB populated with OSM data (osm2pgsql, standart.style). Now I would like to display a hiking trail (http://www.openstreetmap.org/relation/51855). It would also be fine, if I just ...
1
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1answer
21 views

How to make rectangle selection on QgsMapCanvas?

I have this code for create and open raster map: if(QFile::exists(rasterFileName)) { QFileInfo myRasterFileInfo(rasterFileName); m_pRasterLayer = QSharedPointer<QgsRasterLayer>( ...
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0answers
17 views

QGIS algorithms do not work on copies of shapefiles?

I'm using QGIS 2.6.0. I'm trying to run various algorithms such as "SAGA/Shapes-points/remove duplicates" & "SAGA/Shapes-Grid/Add grid values to points" through the sextant toolbox. When I run ...
3
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2answers
162 views

Incorrect display of national characters from Spatialite in QGIS, Windows

I used this tutorial by underdark (thanks much :-) ) to convert my area of interest from OSM file (whole Czech Republic downloaded from Geofabrik.de server). Used OSGEO4W shell (saying "GDAL 1.11.0, ...
2
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1answer
16 views

Error converting a raster to polygons

When I am converting a raster using the polygonize tool, I get this error: ERROR 4: 'C:/Users/Vitor/Desktop/Cartografia EE_Portimo/COS RASTER/cos_raster_reeditada.tif' does not exist in the file ...
6
votes
1answer
5k views

Converting Shapefile to MySQL?

I have used Grass GIS imported a .shp file; I now want to export this file to MySQL. I understood that MySQL will contain the function of all three the files necessary in a Shape file system (.shp - ...
1
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1answer
27 views

Is it possible to create tiles with transparent background using Qtiles?

I had created the tiles from shapefile using qtiles plugin in QGIS and that shapefile layer is a label layer created using MMQGIS plugin. But the thing is I want that tiles with transparent ...
1
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1answer
25 views

How to compute tabulate intersection in QGIS?

I have a base layer of census data in census tracts (polygons). I'm looking to intersect those tracts with a buffer layer but I only want to include those census tracts whose area is over 50% within ...
1
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1answer
274 views

Is there a SWAT model integration for QGIS?

I am trying to use SWAT (Soil and Water Assessment Tool) for watershed management activities. It is a set of commandline tools and needs a complex set of input data some of which can be generated from ...
2
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0answers
15 views

Why does my “Zoom to selected rows” Shortcut not work in QGIS 2.6.0?

I´ve changed a shortcut, in this case "Zoom to selected rows". But now it stopped working. The new shortcut never worked and the originally as well is not working now. The icon gets activ when doing ...
0
votes
1answer
28 views

Got different cell sizes from a rasterised data

I'm trying to rasterize the Land cover data of Nigeria which was obtained from FAO database. During the process of rasterizing the land cover data, I used the following information which gave ...
3
votes
2answers
318 views

Problem operating LAStools in QGIS 2.6.1

I have a problem with LAStools in QGIS 2.6.1. I have never used QGIS to process LiDAR data before. I downloaded LAStools yesterday from the rapidlasso GmbH website. I unzipped the “lastools.zip” ...
3
votes
2answers
288 views

How to find out whether a photo is geotagged or not?

I use a android app called OSMTracker. This app records the GPS track and can take pictures and notes. Using JOSM software, the photos are shown exactly at their coordinates (location) but i cannot ...
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1answer
20 views

QGIS 2.6 : Programmatically setting key value pairs for ValueMap widget

Using QGIS 2.6 and Python 2.7 on Windows 7, I am trying to programmatically insert key value pairs into a ValueMap widget via a csv file. Issue is that some of the values are properly inserted and ...
6
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3answers
2k views

What is XYZ format in QGIS?

Basic question, but I have been asked to export data to an XYZ format. Is this the same as CSV files. I am using QGIS 1.8.0. So i am presuming i select the data I want to export, right click its ...
5
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1answer
206 views

Is it possible to have dynamic layer names in QGIS project?

I have a QGIS project with layers, based on PostGIS SQL queries that use current date. Since the data in the database changes, these queries return different data every new day. Is it possible to ...
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2answers
48 views

How to add 2 layers in qgis and display them at the same time

I added 2 layers in qgis using python but only one layer is shown on canvas. After clicking (anywhere on the canvas) both layers are displayed. layer = ...
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0answers
8 views

How to relate data values from two raster layers?

This is my second posting ! 1 Background I have a number of ASCII files containing a set of single values X, each set in a 1km x 1km grid – the start of each file looks like this: NCOLS 700 ...
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0answers
6 views

How to calculate interval areas in raster?

I would like to know if is possible and how can i calculate the areas from class intervals in one raster? All help is appreciated, Best regards
4
votes
1answer
35 views

QGIS batch shp transform

I have a large number of shape files in OSGB (EPSG:7405), with no .prj file that I would like to convert to WGS84 (EPSG:4326). Can you let me know if this is possible in Qgis and, if so, how, and, if ...
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4answers
221 views

Python script to open many small images in QGIS

I have access to about 1000 satellite images that covers my country. Each of them is associated to a smaller image that is used for browsing the real deal. I would like to write a script that will ...
2
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0answers
35 views
+50

filename of current style in QGIS using Python

I get the name of the current style file using layer.styleURI(). Then, I change the style file using layer.loadNamedStyle(different_filename). However, when I call layer.styleURI() again, it returns ...
1
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2answers
349 views

How to use the QGIS Linear Referencing Plugin?

I'm having trouble getting the Faunalia Linear Referencing Plugin set up properly in QGIS 1.8. I've gotten to the point where I can do the Calibration, but I get a few warnings about missing lines, ...
4
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1answer
257 views

Snap points to line and calculate chainage using Open source GIS

I have a line layer (representing a pipeline) and a points layer (representing valves) and I would like to calculate the chainage of the valves along the pipeline. I assume that I would first need ...
0
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1answer
19 views

Tools to export shps from Oracle database

What open source tools could be used to export shapefiles from an Oracle database. I have tried using QGIS but it does crash way too much.
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1answer
47 views

Why are color settings not saved when exporting to a new file?

I extracted with QGIS a municipality from a state map, then divided it with a grid. I don't want the borders of the grid features to be seen so I changed the color of the map and the color of the ...
1
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0answers
29 views

Connect to QGIS 2.6 Python Plugin function via button on custom feature form

I am trying to connect to a QGIS 2.6 Python plugin function via a custom feature form button. On my feature form, I'm attempting to do a few things : enable the updateButton only if the ...
4
votes
1answer
56 views

Dividing map into features with invisible divisor lines using QGIS?

I'm working with QGIS 1.8.0. Is there a way to divide a map with a grid but make the divisor lines invisible? I have a shapefile as the one in the left and I want it to see as the one in the right but ...
0
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1answer
58 views

QGIS 2.6 Crashed for my own plugin

I had developed a plugin that counts the number of features for a layer in QGIS 2.6. I am using Windows 7 os. It works fine when i loaded a layer. But when I remove that added layer and then if I ...
0
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0answers
15 views

How to get the same cell size after and before been rasterized [duplicate]

The following information were used for rasterization of the land cover of Nigeria but got different cell sizes. The input cell size and the measured cell size of the rasterized are not the same. ...
1
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2answers
42 views

Issue in the popdown box (QComboBox) in QGIS 2.6 Python plugin

I had developed a plugin that counts the number of features for a layer in Qgis2.6. When i load a layer say 'Airport' for first time and click the pop-down box in the plugin,it lists the airport ...
1
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0answers
16 views

QGIS and GRASS r.fill.dir processing times

I am new to the open source software and have performed analysis in ArcGIS in the past. I am learning as I go on this processes for OS. I am trying to calculate stream order (strahler) on a 1 gig ...
3
votes
2answers
671 views

How to debug 'Layer is not valid error' from Python plugin?

I'm trying to understand what goes wrong with a QGIS python plugin. Basically I'm trying to render a series of POINT. The query works fine, at least giving it by hand from inside PostGIS DB: "SELECT ...
4
votes
3answers
2k views

How to compute flow direction and flow accumulation with Qgis?

Any one who had made flow direction and flow accumulation on raster data for filled evaluation model i Qgis? Which tool and plugins are necessary, i haven't been able to find any guidelines on Google
1
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1answer
174 views

Making grid lines opaque so just lat/long coords on map border using QGISGDALPERF?

Can any one help me with adding graticules to my map? I have managed to add a lat/long grid over my map, however I want the grid lines to be opaque with just the lat/long coords on the map border - is ...
3
votes
3answers
67 views

Alternative to OpenLayers plugin for QGIS?

Are there any alternatives to OpenLayers plugin to have Google / Bing maps for QGIS projects? I need an high quality cartography (both aerial and street view) but OpenLayer plugin do not allow to ...
1
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1answer
70 views

How to add fields to shapefile from standalone script?

When I run the following script via OSGEO4W64 Shell, I receive the following error when trying to run the qgis:fieldcalculator algorithm: 'NoneType' object has no attribute 'mapCanvas' I read ...
2
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5answers
2k views

Where to find qgsaffine in the menu?

I installed the plugin qgsaffine but cannot find the entry in the menu bar. Where do I find this. Can anyone here help me with this? best regards desputin
1
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2answers
187 views

Integrate grid and polygon of municipalities keeping the biggest municipality per cell with QGIS (or another)

I have a 9x9 grid and a polygon of municipalities of an extensive area of Brazil. My goal is to have a field indicating the biggest municipality per grid cell. I've been trying with intercept without ...
1
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1answer
10 views

Open and split a 4 channel RGB picture

How can I split an 4 channel rgb pic in qgis? With the value tool I can see 4 channel. I tried to use the RGB to PCT tool but I always get an error (File "C:\PROGRA~1\QGISBR~1\bin\pct2rgb.py", line ...
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2answers
148 views

Where to find Metropolitan Statistical Area (MSA) KML data?

Hello GIS stackexchange, GIS is not my field, so I apologize if my question is very basic. I need this data for a odd job at work. I have been unsuccessful in finding the data from Google ...
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2answers
48 views

Merging shapefile layers not working in QGIS?

How do i merge different vector layers in to one shapefile layer In QGIS version 2.6