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

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Python error when using r.reclass on raster with no CRS

I have a set of GRID data (directory of .adf files) that I'm trying to reclassify in QGIS. I'm using the GRASS r.reclass function to try to reclassify the layers, but GRASS keeps failing and ...
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3 views

Creating groups containing slopes of a specific range

I have a basic knowledge of QGIS and can do everything I need to do to achieve my requirements except the following. I'm trying to graphically show areas of land that contain a set of specific slope ...
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1answer
16 views

Enabling preview in QGIS recent projects?

after installing qgis on win 10 I am missing the map-preview in the recent projects window as I had under win7(see screenshot). where is the setting to enable this?
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31 views

Which is better for measuring actual ground elevation, NED or SRTM?

I know that NED DEM layers are created using mainly Lidar point clouds and that the SRTM derives its data from shuttle-based radar. I have both of these loaded into QGIS and can see that over my study ...
2
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1answer
15 views

Retrieve available PostGIS connections in PyQGIS

Can I retrieve the available connections to PostGIS databases in PyQGIS? I would like to provide a list of available db-connections, and subsequently a list of tables within the ui of my plugin. I ...
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16 views

Calculate obstacle accountability area in QGIS

Still being new to the whole GIS world, I am trying to calculate a regulatory takeoff obstacle accountability area for a given runway. For my case, this is defined as an area as follows. At the start ...
2
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1answer
51 views

How to create a shapefile from xy in .csv file?

I find many difficult to create a new shapefile in a new project following those steps. I think the .csv file is correct (there are only: ID, X coord, Y coord) but when I would create the shapefile ...
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0answers
11 views

Qgis slow on loading project

Is there any work around to mitigate the amount of time QGIS takes when loading projects that have large tables from postgis layers . I have tried to turn off this large layers so they are not in use ...
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16 views

QGIS How and where to save Vektorlayer for fastest access/performance

I am fairly new to working in Q-Gis in a local network, please tell me if I missed some information crucial to answering my question. I have a Vectorlayer containing 36000+ line Objects with a large ...
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1answer
43 views

Update column in .shp from .tab with QGIS

Is it possible to perform in QGIS an "update column" on a .shp table with data from a MapInfo.tab having one field apparently in common? One of the greatest uses of QGIS (for me) is the availability ...
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1answer
14 views

Raster update error when saving heatmap in QGIS

I am using QGIS and I recently added a delimited layer and all my coordinates appear fine , however when I add a heatmap I get the error "Raster update error: Could not open the created raster for ...
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15 views

Icon for plugins in own repository

Does anyone know if there is an opportunity to add icons for your own plug-in in its own repository? like this not like this with green puzzle other illustration I spied on how to implement ...
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1answer
25 views

Is there a way to create a presence/absence matrix of polygons per cell in a grid using qGIS?

I'm working in QGIS with species distribution polygons and I want to know how many cells in a grid does the polygon overlap. I've tried creating random points within the polygon and then used ...
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0answers
20 views

Qgis becomes unresponsive when adding layers

Qgis suddenly won't allow addition of vector layers when running on PC (Lyon 2.12.1). I've reinstalled it, no help. I've recently changed to Windows 10 from 7, otherwise nothing much has changed on ...
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1answer
36 views

Style file with QGIS

I created a very good symbol layout for a current map. I will be creating similar maps just different regions and want to keep the symbols and markers that way they are. The new data will have same ...
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2answers
26 views

How to calculate area in sq m - troubleshooting projection issues in a global dataset in QGIS

I am using QGIS version 2.12.3. I have 3 polygon shapefiles: A, B and the intersect of A and B, which we can call C. All I want is to add a field to the attributes table of each shapefile giving ...
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1answer
40 views

snapping line nodes to points

I have a dataset of manholes and pipes; I want to snap the lines start and end nodes to the manholes if they are within a specified distance. Been trying to find away to do this using PostGIS or QGIS ...
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2answers
27 views

How can I handle NULL values in a color ramp? [duplicate]

I'm mapping areas in QGIS 2.12 based on average pricing, using area polygons (PostGIS) joined with a CSV data table that doesn't have values for areas that didn't have any sales. I'd like to color ...
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1answer
24 views

Locating and adding state layers to a QGIS map.

If I wanted to add layers for a state (Indiana) in a program like QGIS so I could produce several maps (Infrastructure, Water Resources, Mineral Resources, and HAZMAT concerns), how would I locate and ...
2
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1answer
34 views

Get the same coordinates for points after downloading a .osm file

I downloaded a .kml file that contains bike stations which I know the coordinates (latitude and longitude). So I got a layer that contains points corresponding to the stations. Then I downloaded the ...
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15 views

How to select within a distance using QGIS [duplicate]

With QGIS 2.12.3, I have two projected EPSG:2927 point shapefiles, A and B. I would like to create a selection of A points that are within 100 meters of any B point. This is easy in Arc, using the ...
2
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1answer
25 views

QGIS Atlas pages with different raster base layers?

Is it possible to enable raster layers only for specific Atlas pages, without using multiple map Windows? Unfortunately, there is no way to set transparency of raster layers by an expression ...
2
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1answer
23 views

Excel Tables as Labels or Annotations

I would like to take excel tables and place them in a label or annotation so that I no longer have to copy and paste them into the figure layout as picture objects. I know this isn't possible in ...
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1answer
16 views

Error when using viewshed analyis plugin with merged shapefile

I am using Qgis 2.12Lyon and try to run a viewshed analysis to show the intervisibility between several points in more than one shapefile. I have a digital elevation model (.tif) which is projected ...
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0answers
7 views

QGIS Server - I can't update QGIS layers that don't have a geometry field via WFS

I am using some layers that are data only (no geometry field). These tables are related to other geometric layers, as you can see in the config below : When trying to publish in WFS these "no ...
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2answers
33 views

How to turn a point layer into classified proportional circles in QGIS 2.12?

I'm trying to style a point layer representing cities around the Mediterranean following these two rules : The points should be represented as proportional circles, following a classification in 5 ...
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15 views

Looking for real examples of using GIS in logistics and transport systems (maritime, auto, rail) [on hold]

As mentioned in title I'm looking for real examples of using GIS in logistics and transport systems. To be specific I'm trying to find any articles or books with detailed explanation of achieved goal ...
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0answers
15 views

How to get a multi-attributes vector from an SRTM raster in QGIS?

I split an SRTM raster into 3 different raster files representing the altitude, the slope and the exposure, using QGIS DEM analysis tools. How can I output a single vector file with the 3 attributes ...
3
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1answer
41 views

How to create a fishnet/grid along a polyline or polygon

I am trying to generate a fishnet/grid along a line/polyline or polygon boundary in ArcGis 10.3 or QGIS. While it is totally intuitive and easy to generate a box-standard grid, what I am trying to do ...
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1answer
36 views

QGIS: getting NULL values when using “Join Attributes by Location” of lines and polygons

I'm using QGIS 2.12.3-Lyon. I have a polygon layer (~130k square polygons with some small overlaps) and I have imported a road network from OpenStreetMap (via Geofabrik, ~141k road segments) for my ...
2
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0answers
30 views

How to select a WMS layer style in QGIS

WMS standard allows specifying a list of styles for each WMS layer. The users can then use the style name in the URL query parameter "STYLES". If the styles are not specified, "default" is assumed. ...
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26 views

QGIS Modeler different results by calculate the $area

When I use the graphic modeler,add a field and calculate the area, the sum of the area of all records is different to result which I get by calculation in the fieldcalculator. The result in the ...
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1answer
16 views

QGIS Plugin 'make' error on Windows

Creating QGIS plugin via PluginBuilder and compiling resources via simple 'make' works straightforward under Linux (SuSe 13.2). Under Windows 'make' (3.81) produces an error: ...
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1answer
25 views

creating a transparent layer background in QGIS

I have created a heatmap in QGIS to cover my point data and I have saved it as geoTiff so that I can import into tilemill, which I managed to do but my background is black .In QGIS however I want ...
2
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1answer
20 views

QGIS - Installation issue Windows 7 64 bit

I am currently trying to install QGIS but it has been on the same point of the installation for almost 30 minutes. I don't know if it is simply taking a long time to create a folder, but it seems as ...
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0answers
17 views

Reclassification of CORINE map using R

I am trying to reclassify the CORINE map for Hungary to 4 classes in R. but after reclassification, when I import the asc file to QGIS it loads it empty. Am I doing something wrong? ...
3
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2answers
53 views

How to select the most populated neighbourhood of each town in the country using QGIS?

I have data from a national census with population for each neighbourhood, grouped by municipality and town, in the country. I want to select the most populated neighbourhood of each town (there's a ...
2
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0answers
22 views

Spatial Join Hangs on Two Specific Shapefiles in QGIS 2.8

I have successfully done spatial joins with QGIS many times. However, with two shapefiles QGIS hangs or never seems to complete. (I’ve let the process run for over two hours.) I’ve tried all the ...
1
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1answer
29 views

Creating DEM from topography map in QGIS [duplicate]

For my geology diploma project I need to create DEM from topography map my professor gave me to use as a base map. The map is georeferenced. My idea was to draw lines over the izolines of the map, ...
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0answers
30 views

ST_Intersection between MultiPolygon tables leads to gaps, missing intersections

I am trying to intersect two MultiPolygon tables, which are in the same UTM projection, and calculate the area of their intersections. I am getting some surprising results when I examine the ...
2
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0answers
17 views

QGIS Download getting stuck, NSIS error? [on hold]

I need to edit a DBF file, and I tried to install QGIS at http://www.qgis.org/en/site/forusers/download.html. However, none of the standalone installers work. I tried installing 32/64bit, ...
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2answers
36 views

Changing point data coordinate system without moving points in QGIS?

I made a mistake regarding coordinate systems and lining up two layers. I have a raster with elevations in EPSG:2949. I created a point data shapefile and entered about 600 hundred points manually ...
2
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0answers
44 views

Create a layer, edit and save. Where are my features?

I created a layer (e.g. point) in QGIS with QgsVectorLayer from memory: mem_layer = QgsVectorLayer("point?crs=epsg:32630&field=id:string","TempFile","memory") ...
3
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0answers
43 views

Modifying CSV file in QGIS before joining it to shapefile?

I've imported a Delimited Text File that I want to join to a shapefile. Unfortunately, the join field has a ' character before the actual string. I wanted to delete that character, but I can't ...
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0answers
16 views

Recover failed raster calculator operation QGIS

Users can recover their raster calculator algorithms via the "results" panel in ArcMap (i.e., analogous to viewing one's "history"). Is there a similar function in QGIS? In other words, is there a ...
2
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0answers
21 views

How to calculate best path between 2 points from a DEM in Qgis?

I'm analyzing the roads and paths of a region by calculating how effective the communication is in the region. First I calculated the shortest paths between the points using the actual road map. Now ...
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57 views

How to use more cpu while processing in qgis

I'm trying to do some clip process with a quile large layers but the process is too slow. When I see the task administrator, just around 28% of the cpu is being used. I've tried with 32-bit and ...
3
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0answers
34 views

How to create a shapefile having Voronoi diagrams from the shapefile of an existing region?

I have a shape file of a region and I want to generate random sub regions of that shape file using Voronoi class of scipy.spatial package of python. But I am a newbie to GIS. I found out about Voronoi ...
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1answer
32 views

How to import a Composer Template into QGIS Print Composer?

How can I import a .qpt file into Print Composer (Composer Manager) in QGIS. I've tried saving it in the composer_templates folder but to no avail.
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3answers
119 views

How to create one shape file with categories?

In my QGIS 2.12.3 I want to create shape files of different lakes. I know how to do it one by one and this way, each lake gets a different color. But it should also be possible to create one ...