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

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2
votes
1answer
188 views

QGIS: How to merge single polygons to multi part polygons by maximum distances?

I have a polygon layer with a land-use class and ID for every polygon. How can I merge polygons (into multi part polygon) which do not adjoin, but are not further than x meters apart from each other. ...
2
votes
1answer
318 views

QGIS: raster import “nan”

I've been importing raster files in ZMAP format using QGIS 2.4 and 2.6. Some of the files work fine but other files for some reason import a black image with nan as a default black and white value. ...
2
votes
0answers
61 views

Creating QGIS multi-layer Topo Map of Lorraine Region of France?

I have a project I'm working on where I need a QGIS multi-layer Topo Map go the Lorraine Region of France between Metz and Nancy as a starting point, but I don't know where to start. What I need is a ...
1
vote
1answer
212 views

Automatically select small polygons contained within currently selected large polygons - QGIS

I am using QGIS (2.4.0) and I am trying to identify regions in Australia that are close to working mines. For this purpose I have 2 layers: Layer 1 - 535 polygons defining the various regions across ...
2
votes
1answer
146 views

Problem or ERROR in converting from raster to vector!

I wonder if anyone could help me out, i am kind of a beginner at QGIS. I´ve built a DEM for a project that i am developing than i´ve made the slope raster with the terrain analysis,it seemed that ...
0
votes
2answers
104 views

way/tool to automatically generate polygons on map knowing polygon width and height and spacing

I need to create a large number of polygons (say 1000) on a georeferenced mosaic (from aerial photographies). I know polygons' height and width, and I know the spacing between them. I can also provide ...
2
votes
0answers
122 views

Finding the slope of a polyline in QGIS 2.2 Valmiera

I am trying to find the average slope of a water course. I've drawn in the water course as a polyline over a large number of contour lines (the water course is long with a very large catchment area). ...
2
votes
3answers
101 views

Need to extract OSM data for my area from 2 neighbor countries

I need to prepare offline background data for my area of interest which is located around border between Czech Republic and Germany. I need to convert the OSM data to spatialite and then to use in ...
4
votes
2answers
153 views

CRS reprojection

I am trying to change the CRS of one shapefile that is originally in NAD27 to WGS84 in Qgis 2.6. When I proceed to make the change, I still continue to see the file in UTM coordinates... I've tried to ...
0
votes
1answer
36 views

problem changing CRS of a shapefile [duplicate]

I am trying to change the CRS of one shapefile that is originally in NAD27 to WGS84. When I proceed to make the change, I still continue to see the file in UTM coordinates... I've tried to save the ...
0
votes
2answers
309 views

Displaying polylines in different color / Color gradient

Though i am using QGIS, yet I am not confined by tool (can use an entirely different tool or a plugin for QGIS) usage.. Only aim is to get the following: I am reading various shapefiles in QGIS and I ...
1
vote
5answers
1k views

Selectively removing whitespace from a string with SQL

I have two columns of adresses that I need to join. Column 1 has the adresses formatted as "Some Street 12 A" while column 2 has them formatted as "Some Street 12A." Ie. the last whitespace between ...
1
vote
1answer
94 views

QGIS GPS Information Menu Automatically Add Points

We are using a Surface Pro 3 with Windows 8.1 64bit, Bluetooth GPS, and QGIS (2.4 standalone download). We have opened a new QGIS project and are able to connect to the GPS unit within the GPS ...
1
vote
2answers
271 views

QGIS project with PostGIS layers freezes irregularly for minutes

I'm using about 30 more or less complex PostGIS layer in my QGIS project. Some of them are PlanetOSM layer generated with osm2pgsql. The Project loads fast (ca 5 sec). The canvas update by moving or ...
3
votes
1answer
135 views

Is it possible to subdivide scale bar segments in QGIS?

How can I subdivide the scale bar segments in smaller subsegments? I want to style my scale bar like this To make the question clear I edited the posting.
2
votes
2answers
1k views

shapefile for mumbai area or section wise

I am working on a project in which i need to plot data on Mumbai city map section wise or area wise but i am not able to get Shapefile for the same. Can anyone please provide me the link where i can ...
1
vote
0answers
179 views

QGIS 2.4.0 seems to have issues with “Select By Location” for complex polygons. Are there alternatives?

I am attempting to use the "select by location" tool to select polygons from one layer that overlap with certain polygons in a different layer. Unfortunately this is causing QGIS to freeze. Doing a ...
2
votes
2answers
307 views

Highlighting features in qgis2leaf export

I have exported a QGIS map to Leaflet using the qgis2leaf plugin. I am looking for some assistance as to how to highlight features (polylines) when the mouse hovers over it. I just want the polyline ...
2
votes
1answer
48 views

Spatial join by categories in QGIS

I am using QGIS 2.4.0 and I have a vector layer which contains a remoteness indicator which is broken up into 5 categories. I would like to turn this into a layer that has these 5 categories collapsed ...
1
vote
1answer
312 views

PyQGIS export to JSON: writeAsVectorFormat and precision

In my QGIS plugin qgis2leaf I am exporting all layers as JSON into a JSON directory. Therefore I would like to enable the user to define the precision in the GUI. The normal "save as" dialogue in QGIS ...
2
votes
1answer
81 views

How to switch rule-based styles in loop?

I'm a working on a QGIS script that could activate/deactivate rule-based styles of the vector layer in a loop (one active layer per iteration). On the every iteration this scenario should: Activate ...
2
votes
0answers
240 views

How to open a second window in QGIS plugin from a button inside the main window

If I already created a qgis plugin, and i need to create a button inside that plugin that opens a new window, how is that possible? Qt creator won't add a slot unless there are a header file. I looked ...
2
votes
0answers
48 views

What does the Join button in the categorized style tab do?

I'm just studing gis, and I use QGIS. I have found in the layer properties some JOIN and don't understand how can I use It? Maybe someone can help me to undersan it, thank's!
1
vote
1answer
212 views

Why is the QGIS map composer grid showing unreasonable lat/lon?

I need to print a map with coordinates in the format of Degree, Minute and second. CRS is set to WGS 84 (EPSG 3857) for both layers and on the project properties it is set to enable transformation on ...
1
vote
2answers
554 views

QGIS georeferencer - GCP projection problem

In short, the problem is that when Geoereferencer is reopened with a previously edited raster, all the previously saved control points have moved off the image to a location thousands of kilometres ...
1
vote
0answers
59 views

Labels with buffers creates bloated PDF file in Composer

I know this question has appeared before, but the earlier questions appear to be linked to the old labeling engine. I'm running qgis 2.0, which I thought uses the new-generation labeling engine. In my ...
1
vote
1answer
109 views

What QGIS line styles work best with Garmin maps?

I am using QGIS to create some maps to load on to a GPS using the plugin. When I display the maps on the GPS the lines are very faint and I can not distinguish colours and some colours vanish ...
2
votes
1answer
367 views

Is there a way to change the QGIS default CRS?

I'm working in a UTM projection and bringing in dxf layers from a different program. The dxf files are all in the correct UTM coordinates already, but when I bring them in I need to change the CRS to ...
1
vote
1answer
40 views

How to coalesce frames with mencoder in QGIS Time Manager plugin? [closed]

I need some guidance putting the exported frames together from the QGIS Time Manager plugin. I saw your line about mencoder, so I downloaded it along with mplayer, but I'm not sure how to use them. ...
1
vote
1answer
83 views

QGIS vector line layer doesnt accept cyrillic letters

In QGIS 2.6 vector line layer doesnt accept cyrillic letters, how can i fix this? For polygon it it works fine but for line and point it only gives me set of question marks - ?????
1
vote
1answer
339 views

Why does one polygon disappear when merging in edit mode?

I want to merge some polygons into one using the merge tool. But when doing so, one of the polygons just disappears (see screenshot 2). Why does this happen? When I use the simplify tool before, it ...
2
votes
0answers
536 views

Along a line create profile/cross-section lines then extract elevation points from them

I know that maybe this question has got an answer, but I need to extract elevation data from a line of a defined length (p.e. 300 meters). Also I want the software (QGIS or ArcGIS) to draw this lines ...
1
vote
1answer
149 views

QGIS 2.4.0 CRS reprojection creates empty files and goes generally nuts

I consider myself an intermediate GIS user but keep running in a problem with the newest QGIS version I cannot fix and wonder if it may be a bug or if I am just too stupid. The problem mostly centers ...
2
votes
0answers
151 views

How to load all items from a template with pyQGIS in QGIS 2.6 [closed]

Since QGIS 2.6, the LoadFromTemplate method seems not work any more (or works differently?) This is my code to add items in my composer from a template : self.composition = ...
1
vote
0answers
77 views

Connecting points with lines [closed]

I have the centre of some buildings (polygons) and the road network of the area. The road network will be used as a pipe network as well. So I want to connect each building to the main transmission ...
4
votes
1answer
150 views

How to make QGIS abbreviate labels with a dictionary?

I'm trying to use qgis "expression dialog" for labeling a layer. What I'm looking for is an expression that permits to apply some abbreviation rules on the layer. For now i'm using this CASE WHEN ...
0
votes
1answer
335 views

Many ELSE statement in Expression in QGIS (2.6) [duplicate]

is it possible to have more than one ELSE in the CASE WHEN statement in the Expression builder in QGIS? For example: CASE WHEN "population" > 5000 THEN 'big' ELIF WHEN "population" > 1500 THEN ...
3
votes
1answer
673 views

Changing mouse wheel zoom settings in QGIS?

I'm having a problem with the mouse wheel zoom setting on my macbook trackpad. The zoom occurs far too quickly for any level of precision. I noted this comment in the dev log: 2004-08-14 [gsherman] ...
1
vote
1answer
123 views

QGIS - use atlas attribute with 'Like' command

Does anyone know how to use the new get Attribute function in conjunction with the "Like" command? I have a table with an Attribute "Sub_Region" and want to show the features that match the atlas ...
2
votes
0answers
159 views

Create “mean” line from multiple lines using QGIS

I have multiple lines features (also have them in multipoints...) representing similar path (mountain trails, in this case) with various GPS precision, resulting in many lines close to each other, but ...
0
votes
1answer
274 views

Building heights above DEM through field calculator

I have a series of building polygons which I would like to convert to a raster illustrating their height. I have the building heights but not their elevation above sea level datum. I have the ...
4
votes
1answer
754 views

“Singleparts to multipart” vs. “Dissolve”

It seems to me that the vector tools "Singleparts to multipart" and "Dissolve" do the same things. Can someone confirm this, please? Or do I overlook something?
7
votes
1answer
213 views

How to connect centroids of lines sharing the same intersection in QGIS?

I'm looking for a big help to accomplish the following task: I have this street network of the center of Turin (IT), composed by lines representing streets, and black points representing ...
2
votes
1answer
252 views

How to convert a RGB tiff into pseudocolor with GDAL etc?

In QGIS I have made a singleband pseudocolor image out of one of the bands from a RGB GeoTiff. I choose one band and then make a linear color interpolation (see attached image). I now want to do ...
0
votes
0answers
86 views

ArcGIS Online : 'Unable to import this shapefile (a is undefined)'

After saving a shp file from QGIS I get this error adding the shp to ArcGIS Online: 'Unable to import this shapefile (a is undefined)' I tried saving in different projections (WGS1984 (EPSG:4326), ...
1
vote
1answer
160 views

Adding items to DEM in QGIS

Working with QGIS and Grass I would like to produce a ZTV. I have the bare land DEM happily ready to go but would like to add buildings and woodland to the calculation. Can anyone please point me in ...
0
votes
2answers
1k views

How to get image pop ups in QGIS?

I have a map of an area and georeferenced photos. I need to be able to bring the pictures as points and then be able to click at a certain point and an image pop up.
1
vote
1answer
199 views

In qgis using python, how can I get multiple pixels from a raster based on a vector point file

I just started working with qgis, and for the life of me I cannot figure out how to solve this problem: I have several points of interest, these are stored in a shape file (just simple points). I ...
4
votes
3answers
842 views

SVG from QGIS to Illustrator CC gets wrong stroke widths

When I export SVG files from QGIS using the Print composer the stroke widths become a lot wider when importing into Adobe Illustrator. It seems like the stroke width in the SVG translates differently ...
0
votes
0answers
47 views

saga:slopeaspect curvature

I'm using windows 7 on 64 bit and using Qgis 2.6.0.I'm trying to process some Tifs from the console using the processing toolbox and saga:slopeaspectcurvature. This is pretty much how my code looks ...