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

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2
votes
2answers
12 views

QGIS: several layers - query

I need GIS in a research-project to calculate the potential of different energy ressources. I used GIS (ArcGis) a few years ago - now we use QGIS in that project and it feels like I am a beginner ...
1
vote
0answers
4 views

QGIS graphical modeler: how to automatically enter parameters in r.drain.coordinate tool

i am carrying out a cost least path analysis and i am using QGIS. The processing tools i am using are: r.cost.full and then r.drain.coordinate Considering i have more than 1000 layer to process ...
2
votes
1answer
72 views

QGIS suddenly very slow generating atlas on PC?

I have been using happily QGIS for about 6 months, in the last week it has suddenly got much slower when generating an atlas using print composer. I am running QGIS 2.10.1 on a PC laptop (Windows 7, ...
1
vote
0answers
5 views

Unexpected behaviour using ST_Equals() with QGIS

Let's say there is a table 'polygon_a' and a table 'polygon_b'. Each table contains three polygon features. The polygon features are spatially equal. CREATE TABLE polygon_a ( gid serial NOT NULL, ...
4
votes
3answers
55 views

How to select specific rows of polygons from a grid in QGIS?

I have a polygon layer. I would like to select every second row of the polygons but not manually. Is there an expression to select every second row as seen on the picture with Select by expression in ...
2
votes
1answer
162 views

Create a PLSS quarter-quarter grid using QGIS

Is there a way to create quarter-quarter sections (of the PLSS township/range/section grid) using QGIS? I've already found http://ianbroad.com/creating-quarter-quarter-section-grid-python/ but using ...
2
votes
0answers
12 views

qgis2web problem with lots of data

A few month ago I was able to make a polygon map of population: http://supermap.hostei.com Today I opened the same QGIS project and tried qgis2web again. The plugin interface had responding ...
1
vote
2answers
33 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?
4
votes
3answers
741 views

Remove Holes Existing Within a Single Polygon for a specific area in Qgis

I have a shapefile that consists of a single polygon. I have gaps within the polygon that needs to be eliminated, but only the ones that are less than 200m2. I tried different ways but none of them ...
3
votes
1answer
49 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 ...
1
vote
1answer
36 views

QGIS Shapefile edited by multiple users

I have a Vector layer containing 36000+ line Objects with a large number of attributes that is currently saved as Shapefile on a server (local network). Multiple users access and edit this Layer ...
1
vote
0answers
24 views

Problem in polygon division using the union tool from QGIS

I am trying to overlay two polygon layers using the union tool from QGIS, to then compute the areas from the resulting polygons. However, in the resulting layer some polygons are not divided as ...
5
votes
1answer
243 views

Grass NVIZ has no output in QGIS 2.8.1 ubuntu 14.04

I am trying to use the Grass7 NVIZ algorithm from the QGIS 2.8.1 toolbox, on ubuntu 14.04. I have enabled Grass7 in the QGIS processing preferences. I have compiled Grass7 from source, and Grass ...
4
votes
1answer
335 views

Debugging errors of SAGA interpolation algorithms in QGIS 2.0 Processing

I encounter recurrent problems with the geoalgorithms that perform interpolations. No matter technique I use I end with the following errors. As state in OGR tab QGIS is unable to open a file in C ...
2
votes
2answers
42 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 ...
4
votes
2answers
31 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 ...
3
votes
2answers
109 views

How to create in QGIS shapefile a field that automatically returns the current date

I'm digitizing a shapefile in QGIS and I need to create a field that returns automatically the current date.
4
votes
1answer
52 views

Problem Editing a Vector Layer QGIS

I have a vector layer which I need to load and edit (add several attribute columns). I am doing this without opening QGIS, so within a python script. I have the following piece of code for the layer ...
3
votes
0answers
13 views

Thematic map exported using QGIS2Web is extremely laggy

I have made a world thematic map and added layers of data for creating graduated color scheme on the country level. I need a interactive map as an output which shows values when user hover over any ...
2
votes
0answers
18 views

Write userID to field automatically every time an object is edited

Currently every user has to put his/her useriD in a field after every change made to an object in the database. This takes time and can be forgotten easily. Is there a SQL-Command giving back the ...
1
vote
1answer
762 views

Can QGIS open a SDF file created by HEC RAS?

I used the "export GIS data" option in HEC RAS and got a SDF file. Is it possible to open it in QGIS?
0
votes
0answers
7 views

Open Street Map Base Map on QField

I am using QField on an Android tablet, I would like to know if I could use a web mapping service like open street map as a base map. Without having the actual file stored on the tablet?
1
vote
1answer
14 views

Is there a possibility to simply display the next element on a layer?

I have to check all the elements on a layer and I'm looking for an easy way to go through all of them. One option would be to open the attribute table and just always click on the next line and then ...
1
vote
1answer
38 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 ...
4
votes
3answers
7k views

How to merge many individual KML layers into one?

I'd like to open a USGS KML file of bedrock geology for an entire county, but there are over 2,000 individual polygon layers. Does anyone know if there is a way to merge all of these layers together ...
4
votes
1answer
59 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 ...
2
votes
1answer
14 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 ...
1
vote
0answers
18 views

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 ...
5
votes
1answer
665 views

QGIS won't install on Mac OSX, during install says “The Installation Failed.”

I have installed the requirements: GDAL Complete 1.11 framework package Matplotlib Python module and I've made sure these requirements are properly installed by checking library/frameworks and ...
1
vote
1answer
51 views

The ecw files are not visible in the qgis browser (or qbrowser as executed in console). Is this a bug? Or is there sth i need to setup?

version: 2.4.0-1ubuntu2 I'm following a web tutorial at lynda.com about QGIS. In one of the first videos I see there's this preview of raster files. There's the .dem files and the .ecw files among ...
1
vote
1answer
41 views

How to see the 'example provider' in processing toolbox of QGIS?

I would like to create my own provider with the processing toolbox. I see the example provider in my folder C:\QgisWien\bin...\algs\ExampleProvider. It seems to be a good start but unfortunately, I ...
0
votes
1answer
219 views

QGIS web client installation: this.projectSettings.capability is undefined

I am trying to debug my configuration of QGIS web client. I have the same problem illustrated here (the GIS-Browser appears but it keeps loading map for the two sample projects ). Yet following the ...
4
votes
1answer
2k views

Can the units of the measure tool in QGIS be changed?

All, I'm trying to do some error-checking with some rasters I'm creating, and want to measure line distances on the map in feet, rather than meters - which is what the measure line tool seems to be ...
0
votes
0answers
28 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 ...
11
votes
2answers
2k views

Is there a QGIS equivalent of the erase tool in ArcGIS?

Is there a QGIS equivalent of the Erase tool in ArcGIS for Desktop?
2
votes
1answer
37 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 ...
3
votes
2answers
429 views

Plotting X, Y coordinates generated from MySQL database in QGIS

Currently running QGIS 1.8.0 on Mac OS X 10.8.4. I can plot points on a map using the "Add delimited text layer" plugin to get x-y coordinates from a text file. However, I'd like to be able to ...
1
vote
1answer
32 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 ...
2
votes
1answer
54 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 ...
0
votes
0answers
21 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 ...
4
votes
1answer
67 views

New field names after joining 2 tables in QGIS

When joining two files (A.csv and B.shp with a common unique ID) in QGIS the new fields in B.shp (from A.txt) include the name of the field + the name of the file where it comes from (A). For example ...
2
votes
1answer
44 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 ...
1
vote
2answers
36 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 ...
2
votes
0answers
19 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 ...
2
votes
2answers
201 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 ...
1
vote
1answer
38 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 ...
2
votes
6answers
637 views

How to export attribute table with start and end coordinates of lines to Excel?

I am working in QGIS. I have a georeferenced line layer and I want to export the attribute table and the coordinates of start and end points of my lines to Excel. Can I do this with QGIS?
1
vote
2answers
37 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 ...
1
vote
1answer
16 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 ...
1
vote
1answer
41 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 ...