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Questions tagged [qgis]

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

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158
votes
6answers
150k views

Installing File Geodatabase (*.gdb) support in QGIS?

I have spent around 2 days to find the way to open GDB (Esri geodatabase) in QGIS (or any other open source software) but still without success. I have downloaded the newest OSGeo4W installer and ...
45
votes
7answers
39k views

OpenLayers low resolution and/or shifts in QGIS print composer?

I'm having trouble with the OpenLayers Plugin of Qgis and the map composer: If I create an OSM-background layer and if I want to export this, the OSM-Layer looks perfectly all right in the normal ...
18
votes
2answers
10k views

Displaying world country shapefiles centered on Pacific Ocean using Robinson or Miller Cylindrical projection in QGIS?

I wish to display a map in QGIS (world country shapefiles) showing all countries but centered on the Pacific area. I am not familiar with Proj4, so is there any way this can be done in QGIS?
30
votes
5answers
37k views

Fixing geometry validity errors in QGIS?

I am working on ownership data at a US county level. I have one shapefile per county that contains thousands of tax parcels. I need to dissolve the polygons representing parcels owned by the same ...
18
votes
2answers
12k views

Problem with import qgis.core when writing a stand-alone PyQGIS script

I am trying to write a stand alone python script in windows 7 that uses qgis.core and various other qgis libraries. I have found an old question on this subject here: Writing standalone Python ...
25
votes
6answers
31k views

Joining multiple records to single feature using QGIS?

I'm trying to create a join/relate in QGIS where I have a shapefile of buildings and to that I would like to join a non-spatial table (.csv) containing people who work in each building. So I have ...
72
votes
4answers
156k views

Calculating polygon areas in QGIS?

How do I calculate areas of an area shapefile in square meters or in acres (ha)? I didn't find that functionality in the vector tools.
43
votes
3answers
55k views

Reprojecting vector layer in QGIS?

I have a series of layers of lines (shapefiles) in My Project. The CRS of some are different and to merge them they all must have same CRS. When I use Processing/Toolbox/Qgis_algorithims/...
53
votes
13answers
18k views

Seeking QGIS tutorials and web resources?

I wish to familiarize myself with the capabilities of QGIS up to and beyond QGIS version 3.0. Can you recommend some good web resources and tutorials that would show me QGIS' capabilities? I am ...
47
votes
7answers
94k views

Getting list of coordinates for points in layer using QGIS?

I've got a layer in QGIS that is comprised of points. Its attribute table doesn't have (show) the corresponding x and y coordinates for each point. Is there a way for me to extract a list of ...
29
votes
8answers
30k views

Georeferencing vector layer with control points using QGIS?

I have a non-georeferenced vector layer that I need to be georeferenced. With raster layers the task is easy and straightforward, but I have no idea what should I do with my vector layer. I have a few ...
28
votes
6answers
43k views

Changing CSV layer attribute value from text to number in QGIS?

I read in a CSV file for linking to a .shp file. All the variables that are just numbers came in as text. How do I change the text variables to numeric in QGIS?
135
votes
4answers
288k views

Adding Basemaps from Google or Bing in QGIS?

ArcGIS Desktop has the option of using basemaps from ArcGIS online. Does QGIS have any such options?
25
votes
7answers
36k views

Performing Raster Reclassification in QGIS?

Is there a way to perform a reclassify of a raster image in QGIS? In ArcGIS you can do that in Spatial analyst Tools→Reclass→Reclassify Any ideas?
24
votes
1answer
25k views

Understanding QGIS buffer tool units?

I have been trying to figure this out for a couple weeks now and have had no luck getting the buffer tool to accept anything but degrees as units of measure. I have found lots of stuff saying the ...
51
votes
10answers
52k views

Removing small spaces (slivers) between polygons? [closed]

I have a set of polygons representing administrative districts. The districts were digitized by hand, and there are small spaces (slivers) between polygons where the polygons should be touching. ...
57
votes
4answers
77k views

Clipping raster with vector boundaries using QGIS?

I am using QGIS. I would like to clip a raster precipitation layer using an admin boundary layer that is vector data. However the geoprocessing tools seem to be usable only for vector data. How ...
82
votes
3answers
186k views

Merging multiple vector layers to one layer using QGIS?

I've imported several shapefiles which where exported from a Mapinfo .tab. Several tab files are imported resulting in 20+ layers. Afterwards I want to export it to geoJSON; but I'm reluctant to ...
18
votes
4answers
13k views

Finding centrelines from polygons in QGIS?

I was wondering if there is a way to create centre lines from polygons in QGIS? I have a polygon layer, but ideally need the centrelines as a separate file.
37
votes
1answer
21k views

Defining new custom projections in QGIS?

I'm trying to define a projection in QGIS. I want to add North America Albers Equal Area Conic. From the spatialreference site I copied the proj4 line: +proj=aea +lat_1=20 +lat_2=60 +lat_0=40 +lon_0=-...
14
votes
1answer
27k views

Using Elseif Conditional Statement in QGIS Field Calculator?

I am trying to write an ELSEIF conditional statement in QGIS Field Calculator (version 1.8.0). I have used an example I found online: CASE WHEN val < 0 THEN 'negative' WHEN val = 0 THEN "neutral'...
34
votes
2answers
40k views

Creating DEM from contours in QGIS?

I have a shapefile with contours and their heights. Is it possible to make a DEM from contours in QGIS without using GRASS? I found Creating DEM from contours using ArcGIS Desktop? but the answer ...
43
votes
2answers
75k views

Selecting features within Polygon from another layer using QGIS?

I'm using QGIS 1.8 with a PostGIS database and I have three PostGIS-layers in QGIS a lines layer, a points layer and a polygon layer. What I'm trying to do is to select a polygon in the polygon layer ...
32
votes
5answers
56k views

Splitting shapefile into separate files for each feature using QGIS/GDAL/SAGA?

I have a polyline shapefile with about 20 kinds of roads. I would like to know how can I create automatically a vector file for each one. I am aware of how to do it using ArcGIS for Desktop - see ...
15
votes
2answers
11k views

Accessing `processing` with Python?

I want to access the explode lines function in Python outside of QGIS from a standalone script. What module do I have to load in order to use it? How can I access processing? from qgis.core import ...
12
votes
2answers
38k views

How to calculate polygon areas and perimeters using QGIS?

Using QGIS, if I load a polygon layer and make a new column, how do I fill that column with the: area of each polygon and another column with length of the perimeter of each polygon?
5
votes
5answers
8k views

Unable to install ECW support on lubuntu 14.04

I try unsuccessfully to install the ECW support (mainly to use ECW file in QGIS 2.2). We attempt to follow and adapt the howto provided by makina-corpus. My first supprise was the repository ...
13
votes
2answers
16k views

How to completely uninstall and remove QGIS 2.8.1 on Windows Vista?

I want to uninstall and completely remove QGIS installation from my computer(windows vista). I have uninstalled it and when i try to reinstall it says it is already installed on the system.
6
votes
4answers
7k views

Dissolving ploygons in QGIS or Grass to new polygons of defined population sizes?

I have a shapefile with 3800 polygons representing the smallest administrative areas in Ireland. Many of these, in rural areas, have tiny populations, under 100 people. In urban areas, all would have ...
37
votes
5answers
53k views

Smoothing/generalizing polygon in QGIS?

Is it possible to smooth or generalize a polygon in QGIS, perhaps by using a plugin like the generalizer-plugin for lines? I could convert my polygons to lines, smooth them and convert them back to ...
19
votes
7answers
35k views

How do I calculate the latitude and longitude of points using QGIS?

I'm trying to figure out how to calculate the lat/long of points using the QGIS field calculator. Is there an easy way to do this? I saw a previous related question, but it deals with a more advanced ...
36
votes
4answers
58k views

Loading OpenStreetMap data in QGIS?

In QGIS 1.8 I used the openstreetmap plugin to request data from the server, or open a .osm XML file, which produced 3 layers (polygons, polylines and points) in QGIS. This was great (give or take ...
44
votes
1answer
58k views

How to install a QGIS plugin when offline?

Due to various IT policies at my workplace, QGIS is installed on a machine that is not connected to the internet. I wish to install a couple of QGIS plugins on this system. I have downloaded the ...
65
votes
5answers
44k views

Building effective heat-maps?

Using ArcGIS, QGIS, Grass, and/or GVSIG: What are some of the tools and processes involved in building effective heat maps? What are the plugins involved? What are the major data requirements? What ...
18
votes
3answers
27k views

How to add Direction and Distance to attribute table?

anyone who can help. i just want to add direction (Bearing: i.e N 25 35 E) and Distance (Length: 125 meters) as my new field in polyline/line data. is there a plug-in to generate these fields? i tried ...
21
votes
1answer
9k views

Filtering features in other layers of QGIS Atlas?

I'm trying to use the QGIS Atlas tools to build student 'scattermaps', ie. display the school and the students that attend that school, for 215 schools. The schools layer is the coverage layer, and ...
16
votes
3answers
80k views

Changing projection of shapefile in QGIS?

How do I change the projection of my shapefile using QGIS? The default projection is set to EPSG:3003, I want to change it to wgs84 EPSG:32632. When I do a reprojection or I change projection in the ...
41
votes
8answers
45k views

Missing Processing Tools in Vector Menu of QGIS?

I'm missing all the usual processing tools in the Vector menu in QGIS 2.16 (eg vector overlay, analysis, etc). They do appear in the processing toolbox but there's no sign of them in the Vector menu. ...
5
votes
1answer
2k views

Raster incorrectly reprojected to OSGB(27700)

Ubuntu 12.04, QGIS 1.8.0, GDAL/OGR 1.7.3, GEOS 3.2.2 Open a Spatialite db with OS Mastermap poly layer (EPSG:27700); Add OpenLayers Plugin (1.0) from QGIS offical repository; Add a Google Satellite ...
9
votes
4answers
11k views

How to fix QGIS error “Entry Point could not be located”?

Today, after returning from vacations, I started my QGIS 1.7 and got this terrible message: Help, anyone?
48
votes
8answers
145k views

Importing DWG into QGIS project?

I have a lot of DWG files like basemap, and water and wastewater network. How do I import these files into my QGIS project?
49
votes
4answers
32k views

Making spatial view in PostGIS and adding it as layer in QGIS?

In PostGIS 2.0, I am seeking an efficient way to create a spatially enabled view that is viewable in QGIS. I followed the context of Part 2 of @Mike Toews answer to How to create a table from ...
40
votes
4answers
36k views

Joining non-spatial CSV file to spatial data (shapefile) using QGIS?

I have a CSV file which has postcode data in a field, but it is non-spatial e.g. no Easting and Northing. I have a shapefile with postcode in a field and some additional data. I want to join the ...
20
votes
6answers
33k views

Creating points in specified distance along line using QGIS?

I want to use QGIS creating points along the line, but in specified distance. I found two GRASS tools in SEXTANTE Toolbox: v.to.points v.segment I tried v.to.points, setting the maximum distance ...
15
votes
5answers
14k views

How to split a vector into equal smaller parts in QGIS or similar?

i want to divide a shapefile with many tiles into a lot of smaller tiles. I am searching for a smart solution, because manual edits are out of questions Anyone can help or know a nice function?
14
votes
3answers
46k views

Create buffer in meters?

I'm very new to the GIS world, so my problem could be very stupid, but I'm going to try anyway. Objective Given a list of coordinates in longitude/latitude, stored as a .csv file, I want to create a ...
14
votes
5answers
23k views

Reading ODBC connection using QGIS? [closed]

I have a co-worker who manages a large MS Access database that contains X & Y fields for various locations he tracks. We have previously exported the data to CSV and used the QGIS Delimited Text ...
10
votes
3answers
14k views

Installing ECW for QGIS in Ubuntu 12.04?

I have followed various online help guides on how to make ecw for QGIS 1.8 work in Ubuntu 12.04. I had it all working in Ubuntu 10.04 but since migration to 12.04 no such luck. Is there a guide that ...
5
votes
2answers
2k views

Calculating proportional area of polygon within another layer's polygon using QGIS?

I have two polygon layers, model and ntem, whose features overlap and intersect one another. I would like to calculate the proportion of the area of the model polygons which fit within each ntem ...
7
votes
2answers
12k views

Spatially joining polygon fields onto point layer in QGIS?

I have gridded depth points in CSV format that I'm trying to add other map data to, in additional columns. I've tried joining fields, hoping that I could link the Shapefile data to the csv, but when I ...