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

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3
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1answer
1k views

Transform polygon to equivalent circle, QGis

I have a polygon and I'd like to find the radius of an equivalent circle from a particular point within the polygon. The polygon would have a large (infinite) number of points evenly distributed ...
2
votes
1answer
95 views

Concatenate or group by values using spatial join in QGIS?

I have a layer (SQLlite) of city lots and would like to accomplish the following: For each city lot, concatenate the list of unique lot id's which are bound within a radius of 30m from the given ...
2
votes
2answers
48 views

Split Vector Points/Polygons by Vector Grid and assign to relevant grid

I have 3 vector shapefiles (1: Point, 2: polygon, 3: vector grid) that I would like to combine so that the points and polygons are 'assigned' to the relevant grid cell within which they are contained, ...
2
votes
1answer
39 views

Actions undertaken in QGIS somewhere stored as Python code in a history file?

For practioners that are not willing to study all the methods for each class, it would be helpful if every action that was made within the QGIS interface can be looked up afterwards in a history file ...
2
votes
2answers
46 views

Assigning colour to QGIS vector layer fields?

I have a vector layer with a field called "dBM". through query builder, I am hoping to change change the colour of the point depending on the value of "dBM". e.g. "dBM" more than 20 ----> ...
2
votes
0answers
35 views

How to calculate shortest path from points in one layer to points in another layer via roads, in QGIS

I'm a new user of QGIS (and have experience using ArcGIS but zero programming skills) and I'm looking for a way to calculate the shortest path from addresses to subway stations via a network of roads. ...
2
votes
2answers
66 views

Merge single points to multi point geometry

Is it possible to transform a point shape file in single part geometryy to a shape file with multi point geometry based on a attribute. e.g. in the shape are 50.000 records in 700 categories, now i ...
2
votes
2answers
75 views

Is there a call in pyqgis that clips a layer similarly to the Geoprocessing Tool?

I've loaded two shape files using pyqgis like so: data_layer = QgsVectorLayer("lines.shp", "highways", "ogr") clip_layer = QgsVectorLayer("polygon.shp", "highways", "ogr") As the names of the ...
2
votes
1answer
37 views

Issue rendering polygons at global scale when using the Robinson coordinate reference system in QGIS 2.10

I am trying to create a map using the Robinson coordinate reference system (EPSG:54030) in QGIS 2.10, on Mac. I used the 'on the fly projection' feature in the Project Properties. My base layer is a ...
2
votes
1answer
54 views

Why would an SVG output from CartoDB look “squished” when the map doesn't?

I have a map of zipcodes in San Francisco that I plotted on CartoDB.The CartoDB view looks about like I expected: But when I had CartoDB generate an SVG, the proportions are way off. I took the ...
2
votes
1answer
59 views

OpenStreetMap heavily pixellated when loaded in QGIS and standalone application

I am loading an OSM street map into an application I am building. I load it as a raster layer via an XML document with the OSM GDAL data. My problem is that the map appears heavily mangled and ...
2
votes
2answers
198 views

QGIS How to label individual sides of polygon

Using native QGIS layer property definitions, I have successfully labelled each polygon in my layer with its area and perimeter. Never satisfied, I now wish to label each side of each polygon with ...
2
votes
2answers
70 views

Is there a QGIS equivalent of inline variable substitution in ArcGIS?

I am working through some analysis in QGIS and need to iterate through a layer of points and buffer each point and then export to a new layer. I want the new layer names to have the values from a ...
2
votes
0answers
47 views

Importing ArcGIS Vector Layer “drawingInfo” to apply to QGIS layer style?

It is possible to import vector layers in GeoJSON format either directly from an ArcGIS MapServer URI, or from a local JSON file sourced from such. ArcGIS JSON has a "drawingInfo" key (example below). ...
2
votes
1answer
90 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 ...
2
votes
1answer
166 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 ...
2
votes
1answer
175 views

How to group points in QGIS?

I need to group 400 points in 10 groups with 40 points each. The goal is to get the 40 points geographicly together like this: Any idea how to do this with Qgis Pisa?
2
votes
1answer
54 views

QGIS Treat null as zero in raster calculator

In QGIS - I have an irregularly shaped raster - I wish to clip an irregular area out of it (call it raster A) with that area set to null. I masked the area (vector polygon) I want to remove and used ...
2
votes
1answer
122 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 ...
2
votes
1answer
105 views

Relation Reference to simulate filtered drop-down lists

I have a layer of Land Uses that has a 3-tiered classification system (basically so that it can be broken down for different uses by other people). I have managed to create Project Relations and use ...
2
votes
2answers
128 views

Pipeline connectivity

I'm trying to find a way to determine pipeline connections located downstream a critical facility and score how far those connections are from the facility. Any Thoughts?
2
votes
2answers
184 views

How to convert CSV file in VRT

Im a geomatics student. For the treatment I would like to make, I use the gdal executable in QGIS file, with a DOS command. I have a csv file like this (test.csv) : X Y -5.48 42.81 -4.78 ...
2
votes
1answer
99 views

Processing algorithm fails from Python script

I'm trying to write a Python script performing a geoalgorithm. What is surprising me is the following: I first test the algorithm by QGIS (2.8) interface. In my case, the GRASS interpolator ...
2
votes
0answers
89 views

How to change the symbology of selected features in QGIS

In QGIS selected features are normally highlighted in a different color to draw user’s attention on the selection. The default color can be changed programmatically. As a nice to have my standalone ...
2
votes
1answer
209 views

Performing viewshed analysis with Dutch AHN files in QGIS?

i downloaded the new (dutch hight data) AHN files, and was trying to perform a viewshed analysis at some point near UTRECHT. The plugin (grass plugin) works ok, i tried it before with a dem map. ...
2
votes
1answer
69 views

QGIS feature subsets are incompatible with table joins. Bug?

When using QGIS 2.8.2, I am unable join a table to a layer that has a feature subset (Layer Properties > General > Feature Subset). For example, creating a feature subset on a layer prior to joining ...
2
votes
0answers
50 views

Generate ID for the grid of points from top-left corner down [duplicate]

I have a grid of points extracted from a raster. I need to give them a new ID value to be able to join values from it to another grid in rotated system of coordinates.The automatically generated ID ...
2
votes
2answers
203 views

QGIS joins 2 FIELDS

I have an excel with 4 columns (Region; District; village; number of cases) Have a shapefile with dots for villages with many columns including (Region ; District ;Village) I want to plot the cases ...
2
votes
3answers
178 views

An Overpass query for OSM ways; both part of a relation and also a specific tag?

How do I construct an Overpass query to find data on Openstreetmap which is both part of a relation and has itself a specific attribute? Specifically: I'm wanting to find sections of cycle route (in ...
2
votes
2answers
551 views

QGIS 2.8 starts with an error and I am not able to run Python console

I have installed QGIS 2.8 - Wien on Linux Red Hat 7. Unfortunately when I start the application I got this python error: {Couldn't load plugin 'processing' from ['/usr/share/qgis/python', ...
2
votes
0answers
80 views

How to make a model with more than 2 input layers for buffering and merging?

Would it be possible to add more inputs to Buffer and Merge? From what I can see there is a limit of two input layers per both. As far as I know this is possible in ArcGIS's Model Builder but from the ...
2
votes
0answers
92 views

Is there any way to set a processing extent for QGIS:Voronoipolygon?

I was playing around with the QGIS:voronoipolygons command line function from QGIS and noticed that there was no option for setting the processing extent. This causes QGIS to pick the minimum extent ...
2
votes
1answer
859 views

Can we avoid using SIP library when writing standalone QGIS python script

I wanted to write a small custom python script using QGIS functionality. So I started with the QGIS documentation on the custom application section. After having some troubles with the import ...
2
votes
2answers
258 views

How to use `layer.getFeatures()` in a standalone script?

I am following the QGIS Cookbook and this post where it concerns reading attributes from layers. I would like to exploit this method and implement it into a standalone script. Essentially, I want to ...
2
votes
1answer
381 views

GPS Live tracking with qgis android

I have a Tablet 10.1 notes on which I installed QGIS Android (v. 2.8) and a Garmin GPS 62 stc. So I tried to do the "live GPS tracking" by connecting through the USB cable the GPS to Tablet. Next, ...
2
votes
2answers
217 views

What is the “best” way to automate the GIS slope and aspect algorithm?

I am currently obtaining slope and aspect of roofs using ArcGIS as follows: Mosaic several Lidar .asc files to new raster Extract by mask using Mastermap building outlines to get hold of just the ...
2
votes
3answers
121 views

How do I use the field-calculator in QGIS to return the name of a country from a different shapefile?

I have a shapefile that consists of a list of archaeological sites with the x and y coordinates. I have an Natural Earth shapefile for the countries of world. I was wondering how I go about ...
2
votes
1answer
141 views

Polygon centroid coordinates update error

After a week of unsuccessful fighting I'm forced to ask for your help. I have created a table 't_excavations' with fields 'id_excavation', 'geom' (MULTIPOLYGONE), 'longitude', 'latitude' CREATE ...
2
votes
1answer
97 views

Euclidean direction

i'm trying to calculate the euclidean direction, in ArcGIS its very easy using the Euclidean Direction tool of Spatial Analyst but in QGIS i don't find how to do it. Any tips for this in free ...
2
votes
0answers
91 views

QGIS 2.8 Raster Layers Moved [duplicate]

I recently downloaded QGIS 2.8 and opened an existing project in it to check how it handled it and make any changes required. This project includes several raster heatmap layers. My problem is that ...
2
votes
1answer
573 views

Split polygon into several smaller polygons in QGIS

I have a layer of polygons depicting response boundaries, I would like to break each of these polygons into a number of sub-polygons. As this is for an exploratory project, the polygons themselves ...
2
votes
2answers
103 views

In QGIS how do I edit/save data which has no geometries?

In QGIS I can import data tables (CSV in particular) which have no inherent geometry (and no lat/lon columns) into QGIS. There doesn't seem to be any obvious way to manipulate that data (edit/save). ...
2
votes
1answer
187 views

Combine Shapefile with address information

I downloaded a UTM32 shapefile (.cpg, .dbf, .prj, .shp, .shx file, where other available georeferences are GK3 and TM32) that shows the exclusive division of Germany in its municipalities. Above, I ...
2
votes
1answer
226 views

Layer properties dialog in my QGIS plugin

I am developing a plugin which should display some information like geometry of the layer, feature count etc. Now those are currently displayed in QMessageBox.information. I want it to be displayed ...
2
votes
2answers
93 views

How to disolve lines from same layer?

How can I dissolve lines from the same layer so there are no borders in the junction? For example, a crossroad shouldn't have any border (not as seen in the picture). Can you help?
2
votes
1answer
94 views

How does the QGIS construct class intervals?

I'm using graduated style of a point layer to assign a colour ramp to symbols (squares). I assigned manual values to class intervals specifying classes to be: 0.60 - 0.80 0.80 - 1.00 That is, in ...
2
votes
1answer
693 views

QGIS Google Maps Coordinate System

I have some Points in Shapefile with BC Albers Coordinate Syetem and I need to Project them to Google Maps Lat and Long. I tried to do this by using WGS 84 / Pseudo Mercator EPSG: 3857 and ...
2
votes
1answer
112 views

Coloring multilinestringzm M values in QGIS

I have output from a geophysical technique that produces X,Y,Z and scalar value for millions of points, which have been stitched together appropriately (by networkx if it matters) into ...
2
votes
1answer
324 views

How to scale SVG symbol based on zoom level in QGIS?

I am wondering if there is a way to scale SVG files I have stored as blob in a Spatialite database according to the current zoom level in QGIS. My hope is to have the SVG icon resize itself when the ...
2
votes
2answers
273 views

QGIS equivalent for ArcMap join for purpose of distances from points to polygon?

It is relatively easy to calculate distances from points to a polygon in ArcMap by doing a join and selecting the option for creating a field containing the minimum distance information. i.e. it ...