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

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264 views

Removing pseudo-nodes using QGIS Sextante plugin?

I have a road network (vector) that i'm interested in carrying out some space syntax analysis on. Predictably my GIS data is in a pretty terrible state. For example, there are a bunch of roads on the ...
2
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1answer
342 views

QGIS: raster image georeference and overlay

I've created a grid and points in QGIS which I used to survey. Using a test image at the moment and I'm trying to fit this image as an overlay within a boundary. When I insert the image it has a white ...
2
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2answers
170 views

Can the QuickOSM QGIS plugin be used with Overpass QL (rather than xml)?

The QuickOSM plugin for QGIS can support users with the generation of new Overpass queries (for beginners on Overpass like me). It does this using the xml query language. I'd like to also be able to ...
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1answer
61 views

Extracting regional data from vector file in QGIS

In QGIS, I have a random points data (coordinates) with assign values I have plotted it in QGIS with CSV file and now I want to extract the specific region data. How would I do this? Please guide me.
2
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1answer
69 views

QGIS: regular points tool numbering

I've made a regular grid and regular points for a grid, I want to set this inside of a boundary so I have deleted the points outside the boundary. However, when I do this the ID still shows up ...
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0answers
31 views

problem when building a code under qgis 2.8 c++ api

i have this code QgsUniqueValueRenderer *lRenderer = (QgsUniqueValueRenderer *)pLayer->renderer(); QMap<QString, QgsSymbol*> lSymbolMap = lRenderer->symbolMap(); QgsSymbol *lSymbol = ...
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0answers
150 views

Cannot select linesegment in QGIS

Drawing a baseline in an attempt to make a grid. Have managed to draw baseline but cannot select using cad tools "select one linesegment" tool. Worked previously and I'm not aware that I'm doing ...
2
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2answers
108 views

Rotation field is missing in rule-based renderer in QGIS 2.6

I am trying to do rotation of point symbols in QGIS. I am working with rule-based renderer. In other types of classification there is a button advanced (for example in categorized renderer), where I ...
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1answer
66 views

How to convert/export a large number of attribute's information shapefiles to txt/csv format using a python script

I'm using the 2.8.1 Wien QGIS version. I have a large number (more than 5000) of shapefiles that I want to convert to a csv or txt files to extract, to tables, the atributte information. The ...
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3answers
154 views

What's the parameters of heatmap formula on QGIS?

I want to calculate the values by hand to know which parameters effect the result in the image, but i couldn't able to do that because i didn't understand it. I tried with 500 mt and 1000 mt radius ...
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0answers
37 views

Clip only works on some areas, and not on others, despite being from the same dataset

I have a shapefile of provinces (nxprovincias), and another shapefile of small, disconnected areas ("protected areas") that overlaps with the provinces. I want to easily calculate the total area of ...
3
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0answers
75 views

Printing a 1" scale from 2.8.2 Print Composer

I'm working on a small-scale site survey in qGIS, and for engineering purposes I need to print physical copies of the map that can be used with an engineering ruler. Basically, I need a way to print ...
3
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2answers
423 views

Inverted shading with polygons in QGIS 2.8

Is there a way to modify the style of a poygon .shp file so that everything except the polygon is rendered as shaded? EDIT: see these images if you have trouble understanding. I am going for the ...
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0answers
67 views

Problem running intersect vector processing with line shp file and polygon shape file

I have been trying to run intersect on two shp files, one is line, the other is polygon. Although processing appears to take place and a new shp file is created and added, nothing is visible. I have ...
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1answer
45 views

How to get the upstream average of a raster data layer that falls into a river network?

I have a raster layer of a network of rivers and a raster layer of data I want to extract. For each pixel of the rivers, I need to know the upstream average of the data layer that falls into the ...
3
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3answers
56 views

Why does Georef'd image show as a large black area

Using QGIS2.4.0 I just added 2 maps to an existing project. Both are scanned images of pre-1800 plans. One is a jpg file, I georef'd and added to QGIS no problem and plan displays in the project. I ...
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0answers
72 views

Snapping feature nodes doesn't work after feature creation (filter involved)

I've experienced a strange behaviour during editing mode: I have set a filter to 2 features (polygons), part of on of my PostGIS layers: "name"='A' OR "name"='B' After that I have created a new ...
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0answers
42 views

Batch processing ( offset of font marker) in QGIS

I have a group of layers with type linestring. Every line consists of simple line and marker line (font marker). I have a batch file(csv) with offsets of font markers. Do you know if there is any ...
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1answer
255 views

Spatial Query: The query from “LayerName” using “FID” in field not possible

In QGIS Wien, I am performing a spatial query with two layers (points and buffer areas) and receive the following error when creating a new layer with intersecting features: The query from "LayerName" ...
1
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1answer
110 views

QGIS for geophysical surveying?

I need to make 30x30 and 20x20 grid layouts with co-ordinate points in the corners. These points then need to be relayed to a GPS to be able to set the grids out in person and then survey them. The ...
1
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1answer
89 views

Visualising Multiple Routes from pgrouting in QGIS

I am able to Visualise the Single Route from Source A to Target B by the following code in QGIS SQL "id" in ( SELECT id2 as id FROM pgr_dijkstra( 'SELECT id, source, target, cost FROM ways', ...
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1answer
297 views

Layers with the same CRS in QGIS do not line up

I am busy with a project where I have to layer a .dxf and a .kml file but the layers are not lining up. The .dxf file's coordinates are completely wrong and the scale also does not appear to math up ...
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2answers
386 views

How to select features containing specific text string using an expression in QGIS

I need to style a survey parcel polygon shapefile, based on whether the polygon is a mineral claim or not. Unfortunately, the only information on whether a polygon is a mineral claim or not is ...
2
votes
1answer
133 views

Calculating area using dissolve and merge but getting shapefiles with empty attribute tables in QGIS?

I have a shapefile of a country with the 29 provinces. I also have shapefiles with the areas which are protected from construction (there are 4 categories for protection, within 4 shapefiles. Some of ...
2
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0answers
75 views

From track+waypoints to elevation profile with waypoints

I have a track and waypoints (1) imported in QGIS. I want to calculate the closest point from every waypoint to the track (2). Then, I want a table with data that allows me to draw an elevation ...
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0answers
69 views

Creating random points using QGIS?

Has anyone else had any issues using the random points tool in QGIS? When I try using it I'm selecting the option to use a value input field. The tool starts but then freezes once it gets to the 10% ...
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1answer
147 views

QGIS2WEB white screen on export/preview?

When I export my QGIS2WEB project it goes through, but when it loads up in my browser after the export is done all I see is a white background with the zoom/minus feature in the top left hand of the ...
2
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1answer
64 views

How can I save a QGIS project with hyperlinks?

I have already created an hyperlink project using actions, it works, when I click on one point of my shapefile it opens a photo, but when I re-open the project, the action is gone and I have to create ...
2
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1answer
105 views

QGIS Plugins & Tools that replicate Select ArcPy Tools

I developed a complex python application for road generation from GPS Devices that uses a few Arcpy Tools. I want to try and replicate this Applications functionality using a freeware like PyQGIS ...
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2answers
226 views

QGIS2WEB Error when exporting to Leaflet/OL3

I am having all kinds of problems with the QGIS plugins fr exporting my map to Leaflet or OL3. Whenever I try to preview my project I just get a white screen with nothing. Then when I try to Export to ...
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0answers
58 views

How to create displacement vectors in QGIS using GPS points with different dates?

Is there a way to calculate and visualize displacement vectors in QGIS ? I have DGPS points taken at the same place (ground control points), but their position moved over time as they are located on a ...
2
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2answers
290 views

PostGIS - How to calculate linestring length from WGS84 after transforming from OSGB 36

I am having problems getting lengths from multilinestrings after transforming data from EPSG:27700 - OSGB 1936 / British National Grid to EPSG:4326/ WGS 84. I'm doing this conversion to import a ...
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0answers
27 views

line from min to max of a digital elevation model

I have some geometries as multipolygons and a dem (digital elevation model). I need a line from the max value to the lowest value of the dem for every multipolygon. Is qgis a tool i could use or do i ...
1
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1answer
66 views

Update points coordinates directly on the map using QGIS?

I have many locations or points overlapped each other, so is there a way using QGIS that I can update locations directly on the map using QGIS features, please let me know as I'm new to GIS.
2
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1answer
71 views

Update GPS coordinates to overlapped locations? is there a quick way to do so? I'm using QGIS?

If I have two many locations overlapped each other, and I want to update their coordinates to make the view clear and be able to spot the locations? How can I do this easily? I have more than 512 ...
1
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2answers
123 views

How to get ST_MakeLine ready for QGIS?

CREATE VIEW new_line AS SELECT point1.gid, ST_MakeLine(point1.geom, point2.geom) FROM point1, point2 WHERE point1.gid = point2.gid; It's possible to load the layer but QGIS says 'There is no entry ...
1
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1answer
136 views

find the population density of some points in qgis/postgis

I have the tiger census data of population density in each block group. I also have a different kind of data: traffic accident data, where an accident has a lat/lon pair. My goal is to find the ...
1
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1answer
37 views

How do I enable lineweights for my symbology?

I imported an OSM shapefile of roads data. In the layer properties, I classified the roads based on type (motorway, trunk, residential, etc.). I can assign colors but cannot assign lineweights. I can ...
2
votes
2answers
281 views

QgisInterface.addVectorLayer Error

I am Esri-trained, trying to move into QGIS using Python. Simply trying to add a vector layer in Qgis returns the below error: TypeError: QgisInterface.addVectorLayer(QString, QString, QString): ...
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0answers
104 views

QQIG/SAGA “merge shapes layers” algorithm removes underscores/pluses from layer names

I have a bunch of layers that are named layername_number+number that I want to merge. I need their names as source attribute so I used the "merge shapes layers" algorithm found under SAGA in the ...
2
votes
1answer
335 views

How to export the map in very high resolution

I made a map in QGIS. Now I want to export the resulting image (layers upon layers) for further processing in GDAL. The print composer only lets me export an image up to a fixed size. If I try to ...
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0answers
78 views

qgis atlas : problem with scale bar

Good afternoon, I'm working with qgis 2.8 (windows). I 'm abble to generate maps thanks to qgis atlas. But i have everytime a problem about the scale bar. When i generate atlas with "fix scale" ...
3
votes
0answers
143 views

MMQGis plugin error

I am using QGIS 2.8.2 and I'm trying to geocode some addresses, but when I run it, I get this error: An error has occured while executing Python code: Traceback (most recent call last): File "C:/...
2
votes
1answer
326 views

different way to build qgis python standalone application

There seems to be 2 different ways to start a Python QGIS standalone script. The official tutorial is using : from qgis.core import * # supply path to where is your qgis installed QgsApplication....
3
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0answers
82 views

Drawing “proportional” buffer using QGIS or GRASS?

I'm working on aquatic vegetation and have a shapefile representing floating vegetation in a lake. By some studies, we know that submerged vegetation extends for a certain extension based on floating ...
5
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1answer
128 views

How to create multipe labels on polygons?

Is there any tool or function to create muliple labels on polygons? Edit: Meanwhile I've created a point layer for label placement using the refFunctions plugin. geomwithin('polygon', 'label') ...
2
votes
0answers
188 views

QGIS, faulty Zonal Statistics calculations in case of empty polygons

I run QGIS 2.10 on a 64-bit Debian system and am currently trying to do some basic raster vector statistics. However, I found that when applying the Zonal Statistics plugin, I end up with completely ...
0
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1answer
188 views

How can we export shapfile to svg format using Pyqgis

I am doing a project where i have to export file from shapefile to svg format using Pyqgis. i have read some articles regarding simplesvg plugin but i don't know how can we achieve the same task using ...
1
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1answer
58 views

How to restrict panning in QGIS to a given extent

I'm going to build a QGIS standalone application. According to the requirements full extent equals to the extent of a predefined rectangle (say bounding box of a parcel). The application should start ...
4
votes
1answer
417 views

QGIS Export Shapefile

i am trying to export selected feature using pyqgis. till now i have tried these codes. after using this i can select feature but dont know how to export selected feature to new shapefile. canvas= ...