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

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4
votes
4answers
2k views

How to georeference Tiffs after manipulation in Photoshop?

I am exporting very high-res (7000x7000px) hillshades from ArcMap as tiff files. I am then doing some work in photoshop to the images. How can I easily georeference these tiffs after working on them ...
2
votes
1answer
200 views

Why am I losing part of my raster when I reproject?

QGIS 2.0 Working with tiff raster file. Reprojections are in WGS84 Mercator. Here is my problem: I am trying to use buffers or urban areas to analyze light intensity on a raster layer. I want 30 ...
3
votes
3answers
3k views

How to reproject WGS84 to a metric coordinate system with own reference point in QGIS?

I have GIS data in EPSG:4326 consisting of 2D points, linestrings and polygons that are all close (i.e. less then a couple of hundred of meters) to a certain WGS84 coordinate point. I would like to ...
1
vote
1answer
542 views

How do I get the vector output segmentation algorithms to work properly in QGIS 2.0?

I'm trying to run the Watershed Segmentation algorithm, specifically, but I have been receiving the same error message using any of the available segmentation algorithms. I'm new to QGIS and have been ...
2
votes
1answer
134 views

QGis draw over simple jpeg image

I'm pretty new to GIS, and since 2 months ago QGIS is a great tool to achieve very simple tasks, such open some shapefiles I find in the web and load that data on my website geoJSON formatted. Now I'...
1
vote
0answers
262 views

How to apply categorized symbols to polygon layer with PyQgis?

I'm fetching a polygon layer from postgres using the following: uri = QgsDataSourceURI() uri.setConnection("localhost", "5432", "mydb", "postgres", "xxx") uri.setDataSource("public", "my_table", "...
2
votes
1answer
329 views

Why is the map content not displayed when I reopen Print Composer?

I just updated from QGIS 1.7 to 2.0 on Mac. When I now open a project and create a map in the print composer the content of the map is lost when I open the project again later. The settings of the ...
0
votes
2answers
377 views

Unable to implement pgrouting(plugin) pgr_astar routing algorithm (shortest path) [duplicate]

I have been working on a project for indoor navigation. I made the floorplan of the building and road-map for routing purposes as shp files (using JOSM, making GeoJSON and then converting to shp file ...
1
vote
1answer
416 views

Problem connecting local POSTGIS in QGIS

I'm trying to connect to local POSTGIS database using QGIS. I'm using the POSTGIS Tutorial form Buondless (rif. http://workshops.boundlessgeo.com/postgis-intro/index.html). The context is the ...
0
votes
1answer
79 views

Fail to get heatmap from MULTIPOINT column of Spatialite layer in QGIS?

I got a heatmap from a POINT column of spatialite layer. But, when I made another heatmap from MULTIPOINT column, it was blank. What is the possible reason of this problem?
1
vote
0answers
239 views

Install PyQGIS in virtualenv

Is it possible to install PyQGIS in virtual environment? I want to use rendering capabilities in my own application which runs using virtualenv.
1
vote
1answer
75 views

Can't see map after renaming fields using Table Manager plugin

I'm quite the beginner at using QGIS and I'm not sure what I did. I tried renaming two of my columns/fields using the plugin Table Manager, and after changing the names, my map no longer appears. I ...
0
votes
1answer
104 views

Missing Georeferencer

I installed Qgis Master 64 bits on win7 64 16gb of ram and I am unable to locate the georeferencer. All other Gdal application are there, Gdal is active, but no georeferencer. I tried yesterday, ...
3
votes
1answer
87 views

Qgis creating point within complex shapes (with holes) [duplicate]

I'm looking for a tool to create a point in every polygon, that will be placed in the polygon. these are complex shapes with holes. the point must not put in those holes! the "plugin RealCentroid" ...
0
votes
0answers
43 views

QGIS Spatial join many points to single vector [duplicate]

I've got two shape files, one contains many point coordinates and the other vector shapes. There are many point coordinates contained within each vector shape. I would like to perform a spatial join ...
2
votes
0answers
277 views

how do i create clusters of nearby points?

I m trying to create clusters of nearby points (which would be the adresses of my customers around a store). Buffer is not an option cauz i need the zone to be limited by customers, so a polygone ...
2
votes
1answer
290 views

How to properly establish a PostgreSQL connection using QgsCredentials

I'm trying to establish a Postgres connection using QgsCredentials as described here: How to access user credentials in database connection? The only problem is that I cannot establish a working ...
0
votes
0answers
61 views

Rings not displaying on .TAB import to .SHP save

I have some strange behaviour happening when importing a MapInfo .TAB file into QGIS. One feature contains internal rings which are ok on initial import but do not show on the first .SHP save. I can ...
2
votes
1answer
5k views

Clip raster layer with *raster* mask layer in QGIS

Given two input layers 1. The clip layer - an arbitrary layer (though in my case it's a float 1 band geotiff) 2. The mask layer - a paletted raster in which every pixel is either NO DATA or a single "...
1
vote
3answers
330 views

How do I use SQL in the field calculator to populate a new column?

Courtesy of Geofabrik I have a "places" point shapefile which includes in the attribute table a column named "type". As can be seen in the attached image the column contains fields such as "city", "...
3
votes
1answer
494 views

How to count and rasterize polygon overlaps in QGIS?

I have a large number of polygons that are overlapping. I'd like to create a heat map and plan on using raster calculation to do this. My plan: to give each polygon a raster value of 1, and adding ...
7
votes
2answers
562 views

How to load a raster layer at the top of the QGIS ToC?

The following code inserts my new_layer just above the active layer in the QGIS ToC. new_layer = iface.addRasterLayer(...) Instead, I'd like my new_layer to be inserted at the top of the QGIS ToC. ...
3
votes
1answer
57 views

Is there a way to force QGIS to use scaleable markers for map prints?

The implementation of scaleable vector graphs in QGIS is very cool, however, when svgs are used for point pattern fill of polygons, these markers are obviously rasterized, blowing up the filesize of ...
1
vote
1answer
257 views

How to create path based on waypoints?

I am trying to map flight paths and compare historic paths with current ones (so I later need to perform some calculations as distances between them). For this task I am using QGIS on OSX 10.9.1 As ...
1
vote
1answer
69 views

Using QGIS, features are suddenly placed 7.5 thousand kms off correct location

I've been counting an muskrat dens on lakes with aerial photos by creating a feature in a separate shapefile. I checked my progress after doing about 80 small lakes and suddenly, half of the lakes ...
3
votes
2answers
226 views

How to edit overlapping lines?

I am trying to edit bus routes in QGIS. Multiple bus routes can run on the same street. When I want to change one bus route, I select one of them, then I enable editing mode. With the Node tool, I ...
2
votes
1answer
122 views

How to know the date when an image has been capturing on Google Hybrid QGIS?

How can I know precisly the date of different Google Hybrid pictures used in my project in QGIS?
0
votes
0answers
119 views

How to get the color of a vector layer in pyQGIS?

I have see this topic (How to change the color of a vector layer in pyQGIS?) but I'm looking for get the color not to change. How I can resolve my problem ? Thanks
2
votes
1answer
1k views

How to make GRASS and SAGA tools capable to use in QGIS?

I installed QGIS, GRASS and GDAL by OSGeo4w package, and as I finish the installation, I want to use GRASS tool, I face this problem: But I already installed GRASS and SAGA, how to make those tools ...
6
votes
1answer
2k views

QGIS python - identify and highlight features programatically

In QGIS there is an option to select features of a selected layer using a "identify feature" tool. Then the feature get highlighted in a different color and attribute dialog is poping up. like that i ...
7
votes
1answer
4k views

How to draw polygons from the python console?

I've been visiting and revisiting the page on geometry handling in the PyQGIS Cookbook: https://www.qgis.org/en/docs/pyqgis_developer_cookbook/geometry.html but can't seem to figure out how to get the ...
2
votes
0answers
109 views

QGIS: rotatable markers with offset from point

Im wondering, if its possible (in QGIS), to set a rotatable marker with offset from point, like in my example below. Any suggestion?
0
votes
1answer
300 views

Get list of CRS in QGIS by python?

It is possible to get list/dictionary of "Recently used coordinate reference system" from QGIS by python? Or get list of all "Coordinate reference systems of the world" also from QGIS by python.
0
votes
0answers
364 views

QGIS, how to change the centre point of a global map?

I have two global maps I want to show on one map in Qgis, however they each have different centre points, i.e. in one the atlantic is in the centre, and in the other the pacific is. How do I get them ...
1
vote
1answer
311 views

Problem with import CSV files to QGIS 2.0.1

I have a problem with import CSV files to QGIS 2.0.1. I have a file with WGS84 coordinates it looks that: Nr;Longitude;Latitude 1;18,06,23.66;54,83,12.50 2;18,08,81.30;54,73,09.30 3;18,23,47.62;54,83,...
3
votes
1answer
349 views

How to programmatically set a rule-based renderer in QGIS?

These days im in a process of developing a plugin , which highlights/change color of set of features in a vector layer depending on some calculation. i found nice article about QGIS – Rule based ...
0
votes
0answers
21 views

Why cant i buffer vector points imported from csv? [duplicate]

I ve imported a csv file with adresses of stores in longitude and latitude. I ve saved it as a shapefile and i can see the points on a map. Now i m trying to buffer the points to end up with ...
2
votes
1answer
697 views

How to select polygons by distance to a single polygon in another layer?

I have a shapefile A with a group of polygons, lakes. Now I want to select the polygons(lakes) that are within a specific distance to a polygon in a second shapefile, B, with the polygon a city. In ...
1
vote
1answer
169 views

How to install QGIS 2.0 on Ubuntu 13.10?

How can I install new version of QGIS (2.0)? When I try with the indication of the official web site of qgis, terminal write me that the last version of qgis (1.7.5 wrowclaw) has several plugins that ...
4
votes
2answers
916 views

How to get the file paths of the loaded layers in a QGIS plugin?

I am very new to GIS, QGIS and Python so please bear with me. I am using QGIS 2.0 and I would like to develop a QGIS plugin that would display the raster layers of the main window in order to allow ...
0
votes
2answers
58 views

How to get rid of artefact rectangles in QGIS Print Composer?

when inserting a map on the canvas of print composer and moving that map around, quite often, there is a rectangle that cannot be deleted. This rectangle is positioned at the initial place, where I ...
4
votes
2answers
5k views

How to perform SQL queries and get results from QGIS python console?

I'm writing a python script using QGIS API. I have to get results from postgres database table. The table has geometry field and other non-geometry fields. I want to perform SQL queries on non-...
3
votes
1answer
437 views

Get geometry column back when counting points in polygon using PostGIS

I have two PostGIS tables: earthquakes and borders, which contain point data on earthquake locations, and polygons of countries in the world respectively. I want to try and count the earthquakes ...
2
votes
2answers
2k views

How to resize symbols in the QGIS Print Composer legend?

I am trying to map a count data type via graduated symbol against a chloropleth and the legend is too big. The circles of the graduated symbols are the actual size of their corresponding values in ...
1
vote
1answer
141 views

Problems with connecting QDateEdit and QTimeEdit widgets to corresponding Field in QGIS Layer (shp/spatialite)

Could anybody give me a hint how to connect the QDateEdit and the QTimeEdit widgets with a field in a QGIS layer (shp or spatialite). The fields in the QGIS layers are from datatype "date" (dd.MM.yyyy)...
1
vote
1answer
61 views

Problem with QGIS unable to access virtual drive

After a motherboard failure I have had to reinstall QGIS Dufour on a Windows 7 laptop. As I share data with a desktop machine I use LiveDrive briefcase as a virtual drive. With all versions of QGIS I ...
0
votes
1answer
354 views

Polygonize(raster to vector) [closed]

I have been install QGIS 2.0.1.when I use Polygonize (Raster to vector)for convert jpg to shp I get error message such as: C:\windows\123.exe is not recognized as an internal or external command,...
2
votes
2answers
2k views

How to limit decimal places of coordinate values in GEOJSON file using QGIS 2.0.1-Dufour

Using "QGIS 2.0.1-Dufour", I try to convert a vector layer into GEOJSON file using "Save As" sub menu. I get the GEOJSON file, but the coordinates of points have values up to 15 decimal places. How ...
1
vote
2answers
468 views

Draw great circle rays from a single point along specific directions

How can I draw great circle rays starting from a single given point P (for example, from coordinate [34 N, 116 W] in this map) and along directions D1, D2, ... (for example, 30, 45 and 135 degrees) in ...
7
votes
1answer
542 views

How can I get Google Fusion Tables to work in QGIS?

I am using GDAL/OGR 1.10 and QGIS 2.0.1. I am trying to load a google fusion table into QGIS using the method mentioned in this blog post. The only difference is that I am not declaring a email and ...