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

learn more… | top users | synonyms

3
votes
0answers
21 views

Create an optimised path between nodes avoiding polygons entities

I have nodes as a shapefile representing seaports. I have the linear cost of shipping for every pair of seaport (specific shipping cost to go from one node to another node). I want to find a way to ...
1
vote
0answers
30 views

Finding point on line closest to other point: unexpected results [closed]

I'm basically trying to do the same thing as outlined here: Finding the point closest to a point on a near feature However, the results I'm getting with the queries suggested in the accepted answer ...
1
vote
0answers
18 views

How to write postgres source in virtual layer in Qgis 2.1x

In Qgis 2.14, I am trying to create a connection with my postgres database using virtual layer. But in the virtual layer window, how should I write the parameters in source field ? I can't find any ...
4
votes
1answer
54 views

Is it possible to create a round map frame in QGIS Map Composer to create circumpolar maps?

Does anybody know if it's possible to create a round map frame in QGIS Map Composer to create circumpolar maps?
0
votes
0answers
9 views

what can I use to export my maps to .gws format [closed]

I need to convert my data into .gws format. I am using Windsim and the only format it takes for map data import is .gws files. Is this possible with ArcGIS or with QGIS??
-1
votes
2answers
43 views

Merge layers with different geometry

I need to merge two different layers but they don't have the same geometry, in particular one contains points and one is a polygon (province). Is it possible to do so by converting them to the same ...
1
vote
1answer
36 views

Two inner polygons touching and covered by two different outer polygons

I need to create a topology where 1 and 2 touch but don't overlap, a and b touch but don't overlap, and 1 covers a and 2 covers b. Is it possible to achieve this? I've tried various snapping ...
3
votes
1answer
49 views

How can I work with time in QGIS

I would like to make a map displaying how several building uses have changed during the last decades. For example, this building was built in the year 1483 as a monastery, in 1880 it turned into a ...
2
votes
1answer
23 views

Raster rotation on QGIS

How can I rotate a raster layer (global land-mass) to make the 180 deg longitude the center of the map (using QGIS)? 'rotate' function in R is simple but not accurate. Raster has 'longlat' projection ...
1
vote
2answers
38 views

QGISimported CSV points are not visble

I am trying to import CSV file and get no reported errors but there are no points visible. If I click on "zoom to extent" nothing happens (even if I move away from the location of the points before ...
-1
votes
0answers
24 views

Indoor path finding

I am working on an interior geolocation project on Android with Indoor Atlas SDK, and I needed a way to map precise points on the map to LatLong. After trying to code an algorithm that converted x,y ...
4
votes
2answers
52 views

What's the correct syntax to use Processing gdalogr:merge from python?

I am using gdalogr:mergein Python console in order to merge to rasters (.tif) But I don't really understand the first parameter, where I have to put two variables. I get the following error: ...
2
votes
3answers
122 views

How to count classified points in polygons?

is there a way to merge the attribute table of a csv file into a the attribute table of a vector? Join is not the answer for me because in this way the plugin GroupStats that you suggested me to use ...
2
votes
0answers
27 views

QGIS Function Editor/ Python question

I'm currently using the layer_property(layerName,'source') to produce a list of copyright statements for the Print Composer by putting that in an if() statement. However, that isn't very flexible as ...
5
votes
1answer
67 views

QGIS clip vector layer to current map extent

I wonder if there is a way to simply clip a vector layer in QGIS (2.14.1) to the current map extent. Clipping algorithm needs another 'clipper' vector layer as input and 'save as...' saves a vector ...
3
votes
0answers
18 views

QGIS create raster from csv and find raster index [duplicate]

I have a csv with about 2 Mio. entries with X and Y coordinates WGS84 and many attributes. The X and Y coordinate are the south west coordinate of 100 meter by 100 meter grid over a country. But the ...
4
votes
2answers
47 views

How to get layers in x number of subgroups?

I have a project which has dozens of groups and subgroups. E.g.: Main_Group > Sub_Group_1 > Sub_Group_1A > Layer_1A > Layer_2A How can I access ...
1
vote
0answers
27 views

Eclipse PyDev has quit recognizing QGIS objects

I followed the instructions for setting up Eclipse with PyDev to start creating QGIS plug ins found here: http://docs.qgis.org/testing/en/docs/pyqgis_developer_cookbook/ide_debugging.html after doing ...
2
votes
0answers
46 views

Classification and measurement of feature basing on scan [closed]

It`s not entirely a GIS question, however maybe somebody can help. I need to automatically classify and then measure area of certain elements on image. That image is a scan of a thin wood slice and ...
0
votes
1answer
17 views

QGIS algorithm parameter: <ParameterString> [duplicate]

I have been working with the algorithm gdalogr:warpreprojectand have failed several times in the parameter in the title. Now, the problem is solved. It was about the EXTRA parameter. I read 3 books, ...
2
votes
0answers
46 views

Deployment of optical fiber QGIS Python

The subject that I’m working on is the deployment of optical fiber . I have a shapefile which represents a country containing homes. And I have another shapefile representing an infrastructure plan of ...
1
vote
0answers
13 views

Median and Mode estimations in the QGIS Modeler?

I would like to know if there is anyway in which I can combine the available tools in QGIS in the Modeler to estimate median and mode values from a raster (DEM) using polygons. I know the zonal ...
1
vote
1answer
25 views

QGIS Script Editor to get operations between raster and float number

I am looking for developing python codes mainly for working with raster data, in particular satellite imagery from Landsat. I need to write a script (into the QGIS Script Editor) to make operations ...
4
votes
0answers
26 views

Automatically style raster using unique values in QGIS?

In ArcMap, it is possible to automatically calculate the unique values for a raster and then apply a different style to each unique value (see 1st image). However, in QGIS, I have to manually add ...
4
votes
2answers
114 views

Double classification for symbols in QGIS

I am using QGIS version 2.14.1 (Essen). I have symbols that I have classified according to certain value from one of the columns in my shapefile. Furthermore, I was wondering if it is possible to do ...
9
votes
3answers
139 views

How to refresh the attribute table of a layer after editing the table in the DB-Manager?

Is there any way to refresh the attribute table of a layer after editing the table (e.g. add a column) in the DB-Manager?
-1
votes
0answers
19 views

Raster Math By Polygon [closed]

I have a 1 band raster image that I would like to modify based on its intersection with a polygon layer. Each polygon will have a slightly different modification. Can i do this using the raster ...
4
votes
2answers
111 views
+100

How to render layer into png in a standalone application?

I would like to use standalone appliction to apply .qml style to a layer and use QgsMapRenderer() to save it as image on a hard disk. The are a lot of questions like mine at this site and it seems ...
3
votes
1answer
44 views

Topographic Position Index unexpected result in QGIS

I am using Windows 7 enterprise and QGIS version 2.12.2 Lyon. Have found an unexpected result when I use QGIS to generate a topographic position index (TPI) raster from a 30m by 30m DEM. I find a ...
3
votes
2answers
54 views

Label and symbol with condition in layer properties under style tab

I have forest areas. I want to put tree.svg with condition. Layer properties-> style-> background -> shape ->svg Something like this: if (myfield<1300 , then show, ...
0
votes
2answers
34 views

Trouble getting shapely to run

I downloaded the GDAL complete Framework von Kyngchaos which also includes the GEOS Framework and shapely for python. I can import shapely without a problem, but when I try to perform some "geo ...
2
votes
1answer
52 views

Coordinates calculation using QGIS

I am quite new to GIS software. I use QGIS. I have a question that might be trivial. I would like to derive the coordinates (Y and X) for an area. Just to make an example: I have two regions A and B. ...
4
votes
1answer
101 views

Cannot locate GRASS plugin in QGIS 2.14.1 on Linux

I am trying to load the GRASS plugin in QGIS but it is not shown in the plugin manager (no matter if I turn on experimental and deprecated plugins). Under processing / options / providers GRASS GIS 7 ...
2
votes
1answer
25 views

Polygon rendering issue in map composer, QGIS 2.8

Since a picture is worth a thousand words, let's go straight to the point. This is what I get in QGIS main window (and what I'd like to get in QGIS' map composer): And this is what I actually get ...
0
votes
0answers
25 views

Find neighbouring polygons along with line

I am working on Village mapping. I have 2 layers, roads & fields (polygon). I need to achieve Nearest Neighbor analysis as, find out those fields along with roads (all road touch land parcels in ...
1
vote
0answers
30 views

QGIS 2.14 - Saving Lat/Long csv file to ESRI Shapefile Error [duplicate]

I have a csv file that I bring into QGIS 2.14 with standard lat and long formatting. The file displays fine but when I try to save it as an ESRI shapefile I get an error: Export to vector file ...
-3
votes
2answers
45 views

Postgres error: fatal role “username” does not exist [closed]

I by mistake installed PostgreSQL twice, uninstalled one, and now I am trying to create a new PostGIS connection in QGIS but receive the following error when testing the connection: fatal role ...
2
votes
1answer
31 views

In QGIS 2.14.0 The measuring tool is set to Meters even after changing it to feet in settings

I need to measure some lengths in feet, in previous versions I could change the units in the drop down window and it would stay on feet now it reverts back to meters, if you take focus off the measure ...
2
votes
0answers
36 views

Load an (updating) point layer from Access: Problems with pointslayerfromtable algorithm

I'm a python dummy user and in general a QGIS dummy user. I'm using 32 bit QGIS 2.14.1 Essen version. Referred to the post How to load an (updating) point layer from Access? ,i try underdark solution ...
1
vote
1answer
31 views

Creating a customized scale bar in QGIS

I want to create a scale bar in QGIS that also includes the scale written out as text - like 1:20 000 or 1:10 000. I would like it to appear just under the scale bar itself. Can this be done ...
1
vote
0answers
18 views

QGIS individual symbol rotation

I've digitised some symbols in QGIS (2.14.1) as a new Shapefile point layer. I want the symbols to be rotated to different angles. I've worked out that I can have a data defined rotation field in my ...
2
votes
0answers
24 views

How to programatically populate a field_4 after choosing values from other fields

I'm working with QGis 2.8, editing the attribute table of a SHP file, named "myTable". I need to populate field_4 with the conditions listed below: For 1 to n (it runs across records of myTable) ...
0
votes
0answers
19 views

How to change center of map in QGIS?

Is there a way to change the central meridian of a shapefile in QGIS? The file I'm working with is an unprojected world map. Right now, part of Russia appears on the other side of the map, next to ...
1
vote
1answer
26 views

Colour a polygon depending on the number containing of point feature

I have 2 different shape files, polygon and points.I am using QGIS 2.14 as a software. The points are distributed inside of the different polygon shapes. I try to do a categorized map using different ...
3
votes
1answer
44 views

Rule based polygon fill in QGIS

I'm really quite new to QGIS, I want to style polygons fill with raster imagws based on a attribute contained in the property table. What do I have to write in the description in order to get for ...
1
vote
1answer
32 views

How to load vector files from file path in QGIS?

We have around 500 files in different folders. For QC purpose, we've selected 25 files(we have the list of files/path in excel) out of those 500. Is it possible to open all those 25 files(it might be ...
3
votes
1answer
100 views

Automated count for attribute table elements

I need your help for extrapolate from an attribute table the number of elements divided for categories in an automated way (it's not possible to count them manually cause the number is quite huge, ...
3
votes
3answers
105 views

How can I delete Shapefiles in QGIS?

In the Browser it's not possible to delete Shapefiles. In ArcMap you can delete Shapefiles easily within the Catalog. How can I delete Shapefiles in QGIS without minimizing the QGIS-Window, navigating ...
3
votes
0answers
40 views

Changing colours in SVG symbol using QGIS?

I am using QGIS version 2.14.1 (Essen), and I have imported a traffic cone symbol in SVG format to represent some of my data. I was wondering if it was possible to change the color of this symbol ...
1
vote
0answers
21 views

Offsetting polygon borders where they share border in QGIS?

Say you have 2 polygons with different coloured borders, where the borders are shared the colour is problematic. How do you offset/separate them in QGIS 2.10.1?