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

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1answer
264 views

Combining multiple overlapping rasters - retain maximum value?

I have 40 overlapping raster grids (derived from flood modelling software) that I want to combine in such a way so as to retain only the maximum value in any of the given rasters at each grid location,...
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1answer
533 views

How Can I Create a Tin from Elevation Points in QGIS

I have a shapefile of points with values that represent elevation at the given point. I know that I can create a TIN from these points, but the fields in the TIN do not represent the elevation. Rather,...
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0answers
20 views

Does fixed classes exist in QGIS?

I'd like to create several images of voronois polygons in QGIS; each images having differents values joined to the voronois. I tried to load a qml style with the values I want to keep (8 classes : 0>...
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0answers
19 views

Overlapping polygons: how to sum attribute values for areas where multiple polgons overlap [duplicate]

I have what seems to be a fairly simple problem but I cannot find a solution. Any help would be much appreciated. I am working in QGIS 2.8.1. I have a shapefile of polygons, each of which has a ...
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1answer
90 views

Combine several rasters in QGIS

I have a problem combining several rasters into one big raster. Particular annoying is, that I had this problem once before and solved it, but I can't remember how. Unfortunately the other ...
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1answer
165 views

QGIS DB Manager - load as new layer not loading

After successfully running an SQL query on two tables and some results in 3 columns, I would really like to be able to display it in the canvas. Apparently, that function is not doing anything, not ...
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0answers
115 views

Editing data in QGIS Server via WFS in AutoCAD Map (2015)

I have a QGIS Server up and running. I can consult my layers using WMS protocol and edit them using WFS protocol in QGIS or lizmap web client for example, but I am not able to make it work in AutoCAD ...
3
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1answer
470 views

QGIS Join Attributes by Location not working from Python script

I have a shapefile with points, and a shapefile with polygons. I want to sum the attribute value of all points that are within a certain polygon, and I'd like to do this for each polygon in my dataset....
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1answer
49 views

What's the syntax to skip optional saga:catchmentareaparallel parameters?

In PyQGis, I want to use saga:catchmentareaparallel algorithm, in the parameters there is an optional arguments, and I don't want to use them, what is the value should i put on the argument? i try to ...
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0answers
77 views

Relative path in layer styles in spatialite

is there way to store default style in relative path in spatialite??it has layer styles table,and a column 'f_table_catalog'.and in this column pathes are absolute,In Qgis project options i set ...
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0answers
63 views

Algorithm for re-numbering duplicate feature IDs based on distance along line (PyQGIS and QGIS 2.8)

I've got something working for QGIS 2.8 using Python 2.7 on Windows 7, but I am missing an important part of the puzzle. I'm trying to develop an algorithm to number homes. I've now come to a point ...
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2answers
93 views

pyQGIS version of the arcgis tool dice

I'm using QGIS and I have some large features that need to be diced up into features with less vertices. If I were using arcGIS I could use the dice tool If I were only interested in lines I could ...
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1answer
44 views

How to convert GOES-R (15) IR image from gray-scale to brightness temprature

How do I convert satellite IR images taken by GOES-R (15) from gray-scale to brightness temperature? We can download the IR satellite images, and read its RGBA values. But how can we convert this RGBA ...
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0answers
53 views

How can I show a trip on a map, color-coded by how long the trip actually took?

I have a series of origin and destination addresses in a spreadsheet, with start times and arrival times for each. I'd like to plot them on a map, with a line between each origin and destination, ...
2
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1answer
125 views

How to clip a raster by extent using Processing from the Python console?

I want to clip a raster by extent in QGIS with the python console. Here is the description given in the documentation. You have to use the following input parameter: Input layer Nodata value (...
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1answer
75 views

Land cover modifications in different time periods

I have several shapefiles which contain buildings built in different periods from 1948 to 2013. My question is how could I see which buildings for example in were built 1948 but are missing in later ...
2
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1answer
304 views

QGIS Viewshed Analysis Plugin

Does anyoe have a link to or know of a list of raster formats the above tool can work with? I'm on QGIS 2.8 using the latest version of the plugin. I've tried a couple of different raster types and ...
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0answers
46 views

Opening *.lyr file in QGIS without access to ArcGIS for Desktop? [duplicate]

Is there a way to open a *.lyr file in QGIS without using ArcGIS for Desktop? I have no access to ArcGIS, so the solution explained in Adding Layerfiles (.lyr) to QGIS? is not an option. I have a *....
2
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2answers
440 views

Heatmap using Kernel density estimation

I have been trying to generate heatmap using kernel density estimation from python console in QGIS. This is command i'm using: processing.runandload("saga:kerneldensityestimation", "D:/test/Towns....
3
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1answer
112 views

How to add my own GRASS algorithms to Processing?

I need to use algorithm r.bioclimatic from GRASS in QGIS but I see that this algorithm don't exist in Processing Toolbox. A search a way of add this algorithm to Processing and in GRASS and Sextante ...
2
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1answer
790 views

Postcodes mapping

I am new to GIS. I have a list of postcodes and I have to make a map, basically to show distance from a specific area. Concentric ring pull type of map. I don't know how to get my postcodes into a ...
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0answers
31 views

QGIS hide the field in the feature properties form if the field's value is empty

When clicking on a feature with the tool and obtaining its properties, in the form that is shown, I would like to view only the fields that are filled (not empty). In some layers I have 50 fields but ...
2
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1answer
104 views

How to define map extents based on a feature's geometry?

There is a polygon geometry in my QGIS project which represents the extents of my map. Does anybody know how to use the data defined override to get the X/Y min and X/Y max coordinates of the polygon ...
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2answers
259 views

How can I import open street map power grid data into QGIS?

I wanted to download power grid network of Cologne city from following url http://www.flosm.de/en/Power-Grid.html But I could only download in jpg format. I wanted to import this in GIS as vector (*....
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1answer
123 views

How to install QGIS 1.8 plugin QGIS2KML?

I am trying to download QGIS2KML plugin. I went to Plugins → Fetch Python Plugins in the Repositories tab and pasted the url. It claimed that it was successfully downloaded, however, QGIS2KML was ...
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105 views

Use QGIS and Qt dialog forms

I have a QGIS project where there are plots with a attributes like name of the owner, address of the owner, cultivate, and so on. This plots are read from a PostGIS database. The future users of this ...
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2answers
307 views

To select the range of values using Raster calculator in QGIS

I am working on a project where, I need to give ratings for the range of values. I have the following ratings index ratings 0 to 4 4 5 to 8 3 9 to 11 2 12 to 15 1 I am ...
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0answers
72 views

Matching/snapping two shapefiles using node and snapping tools

I am trying to edit my shapefiles through QGIS 2.6.1 Brighton. I used the node tools to snap the necessary nodes to eliminate spaces between two shapefiles. However, while doing it I noticed that an ...
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1answer
211 views

Heatmap failing in QGIS (2.8.2-Wien)

I am super new to QGIS so I may be doing something really dumb, but it doesn't seem to work to create a heatmap in QGIS Desktop 2.8.2 (just downloaded this yesterday so I think it is the most current ...
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0answers
18 views

QGIS - “Error Entry Point Not Found” when launching QGIS 1.8 [duplicate]

I am trying to download QGIS 1.8 on my windows operating system. When I tried to launch QGIS 1.8 a dialog box appears, preventing me from launching the software. This is the error that is generated: ...
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3answers
269 views

How to search within a string to extract data from OSM other_tags?

I am working with OSM data in QGIS and I often need to query items in the other tags field. When I download the data using the OSM download plugin the other tags come in one field so are not easy to ...
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1answer
89 views

Add Attributes from polyline / polygon to polyline layer by best coverage

I have two polyline layers in QGIS containing information on a network and I need to transfer some attributes from the second layer to the master layer. Unfortunately their geometries are not equal, ...
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0answers
89 views

QGIS not interacting with iface from python class

So I'm working on something where i need to use threads from python console of QGIS. The following line of code adds layer successfully iface.addVectorLayer("D:\ArcGIS Misc\Atlas\points.shp", 'Points'...
3
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1answer
75 views

How to access CRS of shapefile in standalone script?

I'm trying to access the CRS of a layer and use this to create a grid. I followed the answer in this post which works great in QGIS but I would like it to work in a standalone script. Here is a ...
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0answers
60 views

How to “output to a raster file” in a standalone app based on a composition?

In a standalone app I want to create a print composer with the map, a legend and a scale bar. I try with different codes but without success. I search in several foruns but I didn't find an answer. ...
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3answers
202 views

GRASS convert raster to points

I have tried to convert a raster to points using this syntax: r.to.vect input=g_kelowna_merged@kelowna_mapset output=g_kelowna_points feature=point I have tried using the GRASS interface in QGIS and ...
2
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1answer
248 views

PyQGIS: how to delete layer from TOC when attribute table is closed?

I'm developing plugin where I want to be able to edit non-spatial table inside the attribute table dialogue. As it seems that the only way to do so is to add this table to the TOC first, I do so. But ...
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39 views

Total area of polygons over latitudes

I'd like to calculate the total area of several polygons along a north-south axis. A bit like this http://www.closr.it/canvas/1307/#/spot There is a similar question with R : Spatial graphing, ...
4
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1answer
161 views

Is there a good way to use Spatialite in QGIS?

I am somewhat disheartened by my experience with Spatialite databases in QGIS. In theory, it could be what personal geodatabases are for ArcGIS: a consolidated, portable format that keeps projects ...
2
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2answers
473 views

How to do a one-to-many Spatial Join/Query in QGIS

Does anyone know if it's possible to do a 'one to many' spatial join based on distance in QGIS? The "Join Attributes By Location" under ->Vector->Data Management Tools is very limited... Just to be ...
3
votes
1answer
133 views

Is it possible to define a custom CRS for a shapefile in QGIS that uses hundredths of a US foot?

I have several polygon shapefiles whose coordinates are defined as 100x their original coordinates projected from the Washington State South HARN State Plane in us-ft (EPSG 2927). I would imagine the ...
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1answer
126 views

How to downgrade from Processing 2.6 to 2.2?

I have QGIS 2.8.2 installed and Processing Toolbox 2.6. I want to test a thing and I need to install processing Toolbox 2.2 in QGIS 2.8.2. Is it possible? How can I do that?
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1answer
50 views

Installing Rectangle, Ovals, Diamonds plugin?

I'm using QGIS 2.6 on Mac and unable to find the Rectangle, Ovals, Diamonds plug ?
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0answers
91 views

Putting Labels at the center or inside a polygon layer in QGIS

How can I put labels at the center or at least inside a polygon layer using QGIS Lisboa (old version). I tried options provided on Layer Properties under placements but still my label just falls ...
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2answers
124 views

In QGIS plugin, How do I determine when layer visibility is turned ON or OFF (changed)

I need to update a vector layer's data when the visibility is turned back on. My update does not occur when the visibility is off. To what signal do I need to connect to catch the visibility change?
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1answer
100 views

Is it possible to change data (attributes) in the .csv of a data vector layer and QGIS automatically adopt this?

I have a .csv with data for 300 points: Each column on the .csv is a particular object and the cells define the amount that is available in each point. If I need to change this amount, is it possible ...
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1answer
391 views

How to create mask file (txt or netcdf) from shapefile using ArcGIS or QGIS?

I have a shapefile of el Congo River Basin dy area. Attributes information is just area. Actually I want create a mask with ones in the river basin and ceros outside to just used later in IDL or ...
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0answers
25 views

Change GRASS module default parameter

I´m new to Qgis and GRASS. I need to change the default parameter skip of the module r.to.vect.lines, from its default value of 10 to 1.How can I do this? r.to.vect.lines [-v] input=name output=name [...
2
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2answers
238 views

Does a SRTM DEM image show details such as fields?

I'm working through the QGIS Training Manual where I have a step to get ... ... raster images (SRTM DEM) which cover the region you have selected for your course. SRTM DEM can be ...
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1answer
344 views

Is it possible to connect a libreoffice database to qgis?

Is it possible to connect a libreoffice database to qgis? I developed a database for our exploration points and would like to connect it directly to QGIS instead of exporting to csv.