Questions tagged [qgis]

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

Filter by
Sorted by
Tagged with
4
votes
1answer
1k views

Failed to create memory layers in QGIS application on Linux

I have written a python class which reads properties of map layers from an XML file and creates appropriate memory layers. I have developed and tested this code with QGIS 2.8.2 on a Windows 7 machine (...
29
votes
5answers
18k views

Joining attributes from nearest point in QGIS?

I have two layers with points, call them A and B, each with different attributes. For each point in A I want to join all the attributes from the nearest point in B. Ideally this would also include ...
35
votes
5answers
7k views

Generalizing polygon file while maintaining topology in QGIS?

I have a polygon Shapefile, which I need to generalize. How can I generalize the poligons and ensure that there are no topological errors like "slivers". I already tried: Vector -> Geometry Tools -...
22
votes
5answers
14k views

Creating equidistant points in QGIS?

I am trying to create points (new layer) at specific distance along the road (existing layer) in QGIS. Creating Regular points every meter at county level using ArcGIS Desktop? gives solution for ...
12
votes
2answers
7k views

Understanding Join Attributes by Location in QGIS?

I wonder if there is somewhere an explanation for the parameters that can be set when running the Algorithm "Join Attributes by Location" in QGIS 2.18. I had a look here: Documentation QGIS Testing |...
12
votes
3answers
19k views

Generating DEM from contour Shapefile using QGIS?

I want to create a DEM from depth contours (shapefile) in QGIS. I've been trying to work out how to do this based on this previous question, notably from this link from that page, however I'm stuck, ...
26
votes
4answers
69k views

Converting vector layer to raster using QGIS?

In qgis in the raster menu there is an item "convert vector to raster". This behaves strangely - I do not understand how it is supposed to work. I can select a vector file, an attribute and an ...
11
votes
5answers
17k views

How to fill holes in polygons automatically?

Is there an option in QGIS to fill holes in polygons automatically by setting parameters e.g. maximum area, distance between borderlines? I want to delete/fill holes that a very "thin"/small.
9
votes
4answers
6k views

Show images related to features in QGIS?

Say for example, if there's a point data with old trees, then when you use the identify tool, you can see the photograph of the tree Or even one level further, the labels displaying these images ...
21
votes
4answers
33k views

Creating fishnet grid Shapefile in QGIS?

How do I create a fishnet shapefile using QGIS? The equivalent task of "Create Fishnet" in ArcGIS.
3
votes
2answers
11k views

How to reclass a raster with reclassify grid values in QGIS?

I'm new in QGIS and I'm trying to reclass a raster with reclassify grid values. I want to reclassify by table, however fixed table has only 3 rows and I need some more, but button to add is not ...
7
votes
2answers
7k views

How do I find vector line bearing in QGIS or GRASS?

How can one extract the bearings from a set of lines in a vector file? I'm trying to find the bearings of several straight vector line segments (simplified contour lines, actually) and can't figure ...
11
votes
3answers
2k views

Styling border to match fill in QGIS?

In the past I have just manually matched the color of the border to the color of the fill, but this can be time consuming. I am wondering, is there any way to have the program automatically match ...
13
votes
1answer
9k views

Accessing raster attribute table in QGIS?

I have some Python code that makes Raster Attribute Tables for GeoTiffs using GDAL. In ArcGIS I can see these attribute tables fine and they behave how I like (as classifications) but in QGIS the ...
38
votes
7answers
18k views

How to create svg symbols that have modifiable fill color, stroke color and stroke width?

I want to create some svg symbols for Qgis using Inkscape, those symbols must have attributes as described in the question. For the last two days, I have been experimenting as instructed by Sourcepole ...
50
votes
6answers
15k views

How can I switch line direction in QGIS?

Something that is hopefully pretty easy. I would like to be able to swap the direction of a polyline/line in QGIS. I made a custom tool to do this in MapInfo a couple of years ago, however I can't ...
26
votes
10answers
43k views

Converting KML to shapefile without losing attributes using QGIS?

I have a KML file with hundreds of points. To each point there is information, such as Name, Power, Age (it's a map of hydroenergy powerplants). If I import that KML file to QGIS, this information is ...
33
votes
2answers
7k views

Can QGIS preserve layers when exporting to PDF?

In ArcMap, when you export data to PDF it preserves the layering within the PDF so that you can turn on/off individual map layers (within the PDF itself). When I export from QGIS to PDF, I don't ...
30
votes
7answers
82k views

Creating new layer from selection in QGIS?

Is it possible to create layers from selection in QGIS? I am using QGIS 1.7.4-Wroclaw. To make it easier for others to see this, here are some pics. I used QGIS 2.0.1-Dufour. SELECT SAVE ADD
10
votes
2answers
5k views

Scale and Z factor have no effect on hillshade analysis in QGIS

I used an SRTM DEM to create a hillshade in QGIS 2.2.0. However, the resultant hillshade seems to be vertically exaggerated. Also, changing the settings for scale and z-factor does not have any effect ...
21
votes
3answers
57k views

Merging/Dissolving polygons by Common Attribute Field in QGIS?

I have joined corresponding Local Enterprise Partnerships table data into a polygon shapefile containing UK Local Authorities. How do I Dissolve or Merge the the Local Authorities polygons by ...
15
votes
1answer
9k views

Calculating distance to points in QGIS

Is there a way of calculating the distance to the nearest points in QGIS? In ArcGIS there is a function called Euclidean Distance, which can take an input vector or raster, and generate a raster of ...
12
votes
2answers
7k views

Georeferencing vector PDF/SVG/DXF linework using QGIS?

I want to create a small web application to visualize election results on a per poll site basis for my city. The result is going to be very similar to what has been done for Berlin here. Hopefully ...
14
votes
7answers
18k views

Georeferencing DXF using QGIS?

I have got myself a dxf which is built with units in the wrong scale. How do I upscale that in QGIS? Note it does open in QGIS, just in the wrong map units and location.
3
votes
2answers
4k views

Getting incorrect slope values from an ASTER DEM in QGIS?

I have a DEM layer from ASTER satellite and I want to get the slope information from it. I use terrain analysis > slope, but the output is so wrong. Why is that? Here is the DEM: And here is the "...
13
votes
2answers
30k views

Clipping line layer based on polygons with QGIS?

I have a line layer and a polygon layer. Both files have the same SRS. I want in a new shape file only the lines covered by the polygons. I tried in QGIS the Vector -> Geoprocessing -> Clip ...
9
votes
2answers
2k views

Why are heatmaps on qgis 2.8.1 produced in the wrong CRS?

I noticed that the heatmap calculation on the new upgrade version of qgis is given the raster map without any coordinate system. Have you got the same problem?
59
votes
3answers
72k views

Installing latest QGIS version on Ubuntu? [closed]

I am relatively new to Linux, so can you indicate the exact commands (step-by-step) that I need to type to get the latest QGIS installed on Ubuntu 14.04. I have tried to follow the instructions ...
27
votes
2answers
33k views

Converting point sets to polygon boundaries?

I'm trying to convert sets of points to their respective polygon boundaries. I think this is something like a Voronoi diagram or Convex Hull, but not quite. I'm sure there's a technical term for it, ...
44
votes
3answers
61k views

Converting ArcGIS (*.mxd) file to QGIS (*.qgs) file?

I recently tried to use QGIS and I wondered if you can convert a draft ArcGIS map (*.mxd file) into a QGIS project (*.qgs file). This would avoid thematize the entire project.
14
votes
2answers
12k views

Computing parameters for QGIS Affine transformation?

I have a vector floorplan (DXF) that I've added to a blank project in QGIS using the Dxf2Shp plugin. I've been reading tutorials and StackExchange threads, but I can't seem to find out how to "...
30
votes
3answers
36k views

Displaying only selected features on map in QGIS?

Not sure if this option ever existed, but the new QGIS version hides a lot of things somewhere else and this seems so simple that I'm kind of convinced it was possible to do this before. I have quite ...
11
votes
3answers
25k views

Opening Esri Personal Geodatabase (*.mdb) using QGIS?

Is it possible to open an Esri Personal Geodatabase (*.mdb; ArcGIS 10.2) in QGIS 2.6? Previous versions were right.
20
votes
2answers
11k views

Seeking QGIS equivalent of ArcGIS Erase tool?

Is there a QGIS equivalent of the Erase tool in ArcGIS Desktop? The Erase tool: Creates a feature class by overlaying the Input Features with the polygons of the Erase Features. Only those ...
18
votes
1answer
15k views

OpenLayers Plugin Error: latitude or longitude exceeded limits

I'm aware the 'traceback' OpenLayers plugin error has been dealt with before, so apologies for raising the issue once again. Unfortunately for me, the solutions posted were way over my head, e.g. ...
14
votes
5answers
24k views

How to calculate raster statistics for polygons?

how can I calculate sums, averages etc of raster-points (multi-band) per polygon of a vector-layer. I was told that this is called "zonal statistics". I tried that with QGIS first. There is a way to ...
11
votes
3answers
12k views

Splitting all lines in layer at vertices using QGIS?

I want to automatically split all lines in a QGIS layer at their vertices (like this). I've done a google search and found this article, which is quite close but the workflow is complicated. Because ...
34
votes
5answers
35k views

Converting .shp into .gpx using QGIS?

I would like to convert .shp into .gpx. Using GIS, I open my shapefile and I tried to "save as" gpx but it gives an OGR error: creation of field ObjectId failed (OGR error: Field of name '...
17
votes
4answers
22k views

Converting Polygon into single or all Points using QGIS?

I want to convert polygons into points using QGIS. I know how it's done in ArcGIS Desktop.
13
votes
2answers
23k views

How to enable projection transformation in QGIS

My QGIS project has two layers, one layer is retrieved by Google layer plugin which fetches the static Google map image whose CRS is +proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +a=6378137 +b=6378137 +...
13
votes
2answers
18k views

Getting tabular statistics from table using QGIS?

Are there QGIS tools that will allow users to get tabular statistics from their table? I kind of expected I would be able to just open the table, select the field I was interested in, right-click on ...
13
votes
1answer
19k views

Transforming polygon to linestring in QGIS?

I have a polygon, imported from a shapefile in QGIS. I would like transform it to a linestring instead so I can save it as a GPX file later. How can I transform a polygon to a linestring in QGIS?
7
votes
3answers
4k views

Iterating over layers and export them as PNG images with PyQGIS in a standalone script?

I would like to export specific layers as a png from a QGIS .qgs map. From the table of contents the script would first export the "boundary, climits, and Div1_Irrig_1956_0" layers as one png. The ...
12
votes
2answers
5k views

Raster generalization - buffers in rasters, expand pixels?

Is it possible to create buffers for pixels of raster files? Actually I need to expand the pixels classified as 1 (in white in the figure) with a spatial range of 1 or 2 pixels, in order to perform ...
5
votes
2answers
10k views

How to perform a slope analysis in QGIS? [duplicate]

I have contour information in the form of line features (see picture below) and I want to do a slope analysis in QGIS. Is it possible?
33
votes
8answers
57k views

How to determine the centroid of polygons?

I have a polygon vector and I want to quickly attain the centroid of this polygon for insertion in a text document. I am working with QGIS. I searched through other questions and although some are ...
20
votes
2answers
45k views

Create polygon layer from polyline layer

Our systems expect polygon shapefiles, representing a collection of non-intersecting and geometrically valid (multi)polygons. Specifically, farm fields. We often receive our representations of farms ...
28
votes
7answers
29k views

How to set all pixels with value <= 0 to “nodata” in DEM raster?

I have a DEM raster with pixel values between about 3000 and -0.0003. I need to set all pixel with a value of 0 and smaler (<=0) to "nodata" (for later raster calculations and to reduce the ...
6
votes
2answers
11k views

Nearest distance between point layer and line layer, QGIS

I have two layers , line and point layer. I need to make a line layer which connects all points to nearest line features? Did someone make a plugin for qgis? This is very important tool which missing ...
3
votes
1answer
6k views

Finding nearest line to point in QGIS? [duplicate]

Given a point and few lines, how should I go about finding the nearest line to the point? I am aware of Finding nearest line to point using ArcGIS Desktop (ArcObjects/ArcPy)?, but that is in ArcGIS ...