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

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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 ...
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13 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
13 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
5 views

QGIS 2.8 Error 1: Can't Load reauested DLL

Greetings, I am attempting to run the Topographic wetness index tool in QGIS with Windows 7. When I run the tool, I get this error: SAGA execution console output C:\PROGRA~1\QGISWI~1\bin>set ...
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0answers
20 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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12 views

QGIS2WEB white screen on export/preview

I got another question for ya guys about QGIS2WEB. When I export the 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 ...
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1answer
20 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 ...
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1answer
28 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
17 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
13 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 ...
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23 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
15 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 ...
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1answer
28 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
46 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
31 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 ...
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1answer
34 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 ...
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1answer
24 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 ...
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2answers
35 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
13 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
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1answer
63 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
21 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" ...
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0answers
18 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 ...
2
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1answer
40 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 ...
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0answers
39 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 ...
2
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1answer
63 views

How to create multipe labels on polygons?

Is there any tool or function to create muliple labels on polygons? I've already created point geometries which refer to the polygon geometries but QGIS gets slower and slower with every new ...
2
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0answers
20 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 ...
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1answer
40 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 ...
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1answer
29 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
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1answer
61 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= ...
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0answers
28 views

Error: GRASS 7.0 and QGIS 2.8.1 in Linux Mint from the ubuntugis-unstable

I have installed GRASS 7 and QGIS 2.8.1 from the https://launchpad.net/~ubuntugis/+archive/ubuntu/ubuntugis-unstable (Trusty 14.04) in Linux Mint 17.1 64bit(sudo apt-get install postgis libgdal1h ...
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0answers
22 views

Maps with numbers and postcodes using QGIS?

I have a list of UK postcodes and a number of participants in a survey. I would like to map the first three letters of the UK postcode and I would like a shape....a circular shape for example which ...
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2answers
31 views

QGIS2Leaf Plugin installation error “cannot import name AlgorithmDecorator”

I have been using the qgis2leaf plugin and succeeded in creating interactive maps, adding legend, photos, etc. But suddenly I noticed that the OSM base layer has disappeared and the polygons are not ...
2
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1answer
57 views

How to create a sequence for a table which was created by selecting data from another table?

I have created a new table by selecting data from an existing table: CREATE TABLE polygon2 AS SELECT gid, geom FROM polygon1; CREATE SEQUENCE polygon2_gid_seq; SELECT SETVAL('polygon2_gid_seq', ...
2
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1answer
33 views

Qgis2leaf doesn't show layers with scale-dependent visibility

When I add layers to the QGIS2LEAF dialog box it accepts it and opens up the preview in my web browser, but when I starting looking for the layers, in this case points for campgrounds, I dont see any ...
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0answers
22 views

QGIS 'Clip raster by mask layer': Problem loading output [on hold]

I'm using QGIS 2.8, currently developing a python plugin and at some point I have to execute consecutive processing algorithms. When it comes to loading the layer created by GDAL algorithm 'Clip ...
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0answers
20 views

QGIS Wien 2.8. Openlayers plugin doesn't work [duplicate]

I have installed the latest version of QGIS wien 2.8. Windows 8.1 downloaded the stand alone version from official QGIS website. I had to uninstall the latest one I had because Openlayers plugin was ...
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1answer
16 views

Getting NULL-values when point sampling USGS (SRTM 1 Arc-Second Global) grid (QGIS 2.8.2)

I use the Point Sampling Tool in QGIS to transfer gridvalues (of DEMs) to point features. This goes well with grids from f.i. MapMart (SRTMHARRIS_DEM), but I get only NULL-values when using grids from ...
2
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0answers
25 views

QGIS : transformation types in geo-referencing

Im a beginner in geomatics. I try some images georeferencing in QGIS. I would like to understand what is happening behind the different transformation types (linear, polynomial, Helmert...). What I ...
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0answers
27 views

ArcGIS and / or QGIS and UAV tech [on hold]

I see it has been almost a year since the last "UAV and GIS" question was asked here. Finding some incredible youtube videos recently showing remarkable results doing UAV and GIS together here and ...
4
votes
2answers
108 views

Meaning of GCP in QGIS

Im a geomatics student, During a geo referencing with QGIS, a .Points file is saved. I open it with Notepad++ It is written under this form : mapX,mapY,pixelX,pixelY,enable ...
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0answers
14 views

Error in merging two raster files (precipitation) in QGIS

The newly computed geotiff shows the extent of both raster layers, but only the data of one. If I use identify features tool it gives me only the values of the visible part not of the other part. I ...
2
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0answers
34 views

Why value relation doesn't work when I delete and connect reference layer?

I'm trying to connect reference table (domain) with data(text) to my vector layer (id's) using value relation. I have database in Oracle connected. It works fine, but when I delete the reference layer ...
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1answer
31 views

trigger postgis and dump qgis 2.8.2

I created a trigger that checks if geometry is valid on insert and update. create or replace function check_geom() returns trigger as $$ begin --insert a polygon IF st_isvalid(new.geom) = 'f' ...
2
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1answer
44 views

How to perform viewshed analysis with Dutch AHN files?

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. ...
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0answers
20 views

QGIS Spatialite Views problems

I am trying to wrap my head around spatialite views in QGIS. However there are severe limitations that make it very cumbersome: Spatialite views in QGIS do no update, if the corresponding tables in ...
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1answer
27 views

How can I create polygons for a 3D map from a DEM in grass/qgis

I have a SRTM 30m DEM of my area. I want to create a physical 3D terrain map from it (from felt, 3D printer, you name it). I have two questions about this process: With grass r.contour I created ...
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0answers
14 views

How to export from WINSTAR to ArcGIS [on hold]

I have data in a very old "winstar" type of format. However, currently I only use ArcGIS for Desktop and QGIS. Does anyone have an idea on how I can import this old-fashioned winstar stuff to ArcGIS ...
2
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1answer
33 views

How can I copy non-blank values to a new column from different columns in the same layer in QGIS?

My data: n1 n2 n3 NEW_COLUMN 11 null null null 33 null null null 55 My desired result: n1 n2 n3 NEW_COLUMN 11 null null 11 null 33 null 33 null null 55 ...
2
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0answers
11 views

Remote sensing Classification and texture analysis compared with QGIS zonal statistics

Some back round: Using Geomatica to analyse suburban spectral signature in Las Vegas. Ran a texture analysis on all band images. Combined texture bands with original image bands to run an unsupervised ...
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0answers
14 views

Toggle layers on print composition

I want to use QGIS to make several views of bold colors for one same map. I've been using the layers in order to keep one on top of another. How could i make a composition on the print composition ...