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

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188 views

How to colour contour lines in .shp file when the lines are not meeting in QGIS?

I am doing bathymetry analysis, where I would like to color the contours one by one in the case land is rising (or sea level going down). There is a comprehensive explanation about coloring contours ...
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0answers
72 views

How to calculate the area of overlapping buffers within a single layer

I am very new to GIS, so don't know if this is EXTREMELY easy or impossible. I have GPS coordinates for stores (about 15000) for which I have created a buffer zone around each store location ...
1
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1answer
73 views

Is it possible to set symbol layers always on top?

Is it possible to set symbols always on top, also if the layer with the symbol is drawn under another layer? Example: My layer order is like that: Streets (top) Buildings Landuse (bottom) The ...
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0answers
39 views

Why does the “calculate” button remain gray in Group Stats Plugin?

I'm trying to use the Group Stats Plugin. I found your tutorial and I wanted to post a comment but I have seen that it is not possible then I thought to write here. Unfortunately I can not use the ...
1
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2answers
249 views

How to resample a raster to higher resolution in QGIS?

I'm fitting a SDM using R. A requirement is that all environmental predictor layers have the same extent, origin and resolution. I have high resolution bathymetry data (25m) that I will resample to ...
1
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1answer
60 views

How can I convert SRTEXT to PROJ4TEXT with QGIS

I have a SRTEXT like this: GEOGCS["My Data",DATUM["Not specified (..... I want to get PROJ4TEXT of this STREXT. Can I get it from QGIS. Because I want to insert it in Postgresql SPATIAL_REF_SYS ...
1
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1answer
50 views

Attribute table in map composer is limited to 99 rows. How to change it?

I am using Qgis 2.2. I am about to create a cadastral index map, which are showing the parcels in specific gridcells, also there is an attribute table connected controlled by an atlas function. So by ...
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2answers
406 views

Using ST_split to split a line feature using nearby points

I have a line shapefile and a point shapefile, and the line has just one segment and its attribute table, the point shapefile has points near the line above, not on it and the close ...
1
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1answer
45 views

Why are some QGIS 2.2 bar graphs not displayed?

I created a vector layer containing all European countries and some double information about them. I'd like to show this information for every object in a bar graph. My problem is that the bar graphs ...
1
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1answer
847 views

TIFF to MBTILES conversion on a mac

I have a large number of tiff files (map tiles) along with tab and tfw file types as part of an Ordnance Survey download. This is for an offline iOS app. I managed to get the tiffs into QGIS with ...
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2answers
225 views

Where to find Metropolitan Statistical Area (MSA) KML data? [duplicate]

Hello GIS stackexchange, GIS is not my field, so I apologize if my question is very basic. I need this data for a odd job at work. I have been unsuccessful in finding the data from Google ...
1
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1answer
32 views

QGIS Custom CRS has some glitches

I am georectifying scanned versions of Survey of India maps, which are in Everest spheroid and india_nepal datum. The exact parameters are: +proj=longlat +a=6377301.243 +b=6356100.2284 ...
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0answers
54 views

Converting/clipping KML to shapefile in QGIS without truncating field information (data)?

While I am clipping KML file by using polygon shapefile in QGIS, filed information (data) are truncating .Anybody can suggest a solution for this one.The same data losing issue occurring, at the time ...
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2answers
261 views

Exporting to 2D (Arcview 3.0 compatible) shapefile in QGIS?

I need to run my shapefiles through a web mapping application which is incompatible with 3D shapefiles. At present I run them through the FME Universal Translator in Mapinfo, which enables you to ...
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0answers
21 views

Update joined tables fields when the mysql database is updated

Using Qgis i joined feature tables with tables from my mysql database. I imported the database 's tables as new vector layers. Is there any way to update the joined tables fields each time mysql ...
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0answers
331 views

QGIS GRASS plugin missing!

I just installed QGIS version 2.2.0-Valmiera on my mac with OS X. First I installed all required frameworks. QGIS is running, but the Grass plugin is not existing. In the toolbox the grass tools are ...
1
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1answer
41 views

Why does Points in polygon create empty PNTCNT column from OSM points?

I tried to use the Points in polygon tool in qgis 2.2.0 and it worked fine as long as I used my own points. When I tried to 'count' the points generated from OSM layers both from dowloaded ...
4
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1answer
142 views

Can I use a QGIS geometry in a Python PostGIS query?

I have a "Python Init function" for the attribute form in QGIS, which is called when I add a new geometry. I can access the geometry of the newly created feature like this geom = feature.geometry() ...
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1answer
195 views

Labels appear and disappear for no apparent reason using QGIS?

I'm going through the Alaska sample data tutorial for QGIS 2.2.0. Some of the lake labels appear and disappear at different scales when zooming. At 1:314,460 Becharof is visible, but Lower Ugashik ...
0
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1answer
57 views

How to put marker on vector layer with lat/lon on QGIS [duplicate]

I have a vector layer, and bunch of lat/lon values. I want to put markers on the vector layer for each lat/lon pair. I have never used QGis, would you help with it. thanks.
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1answer
181 views

Convert Road layer shapefile into a graph

I'm going to use Astar algorithm to find a path between two selected points.And I used the following code for that.Is there any way I could convert my Road Layer shapefile into a graph, which can be ...
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0answers
148 views

QGIS 2.2.0 GRASS not worked

I use QGIS 2.2.0 on Windows 8 64 bit. I try to install use Standalone installer and OSGeo4W and still get the error And then i start GRASS C:\Program Files (x86)\GRASS 6.4.2>grass64 ╬╪╚┴╩└: ...
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0answers
130 views

How to add a large inset svg or pdf in QGIS 2.3 print composer?

I have a 48x36 wall map that will include 5 large inset maps, the largest of which is almost 11x17. Due to a bug with html annotations, I need to export each inset individually then include them as ...
1
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1answer
254 views

QGIS Slope Classification Issues

I am very new to QGIS for the primary purpose of creating a slopes layer so we know where slopes are above 15% or 20% or whatever we finally decide. I have used our DEM to create a slope geotif and ...
1
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1answer
105 views

How to filter data by category, then map only maximum-value row for each?

I'm building a consolidated map of all transit systems in my area in QGIS. I have a GTFS dataset of bus lines, and it includes shapes for every trip on every route in the system (as it should), but ...
1
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1answer
590 views

QGIS contours smoothing and cleaning

Trying to utilize the contour extraction QGIS tool but having trouble creating smoothed contours. The smooth, generalize, and dissolve tools have not worked for me. Also the plugin for contours ...
2
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1answer
81 views

Is it possible to create Rule-Based Styling with $geometry intersecting a second layer?

I am trying to create a rule-based style based on geometries from another layer. I have found an example that does exactly what I want, except that it uses a geometry from WKT: intersects( ...
3
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4answers
235 views

How to make an editable City Map from OSM data?

I want to make a map of Cardiff, Wales, showing features useful to tourists, e.g. roads with road names, parks, museums, other POIs, etc. I want the final map to be clear to read - simple roads and ...
1
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1answer
69 views

shp2pgsql data appent without gid

I have a shape file, I opened it in QGIS that has columns in attribute table named CITY_NAME, POPULATION and I have a database table in Posqgresql that has columns named gid (primary key), ...
1
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1answer
317 views

Convert shape file to kml without losing symbols

I am using QGIS 2.2 and want to convert a shape file containing point coordinates with userdefined svg-symbols to a kml file. Everything seems to work. The orginal file is in WGS 84 / UTM zone 32N ...
3
votes
2answers
105 views

Method for automatic aggregation of polys with sparse data

I am part of a project on presenting health related data on maps. In order to maximize the analytical usefulness of the data, we wish to divide them into as small areas as possible. However, to ...
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3answers
1k views

Calculating slope in percentage

I'm working with qgis, v. 2.0.1. I have several soil types. They are (amongst others) described with slope indications. I already calculated the slope from the dtm in degrees, but as de description of ...
2
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1answer
165 views

How to add an interpolation raster from the python console in QGIS?

I'm trying to add an interpolation layer based on an existing vector layer by using the Python Console (initially in the menu Raster/Interpolation), but can't find anything related in the ...
0
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1answer
179 views

How to open QGIS using VBA?

Using VBA, I want to open QGIS (the actual GUI) and execute a simple script through the Python console or the editor.
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2answers
419 views

How to add polygon height in QGIS or PostGIS?

Is there an easy way to set the height of polygons in QGIS or PostGIS? I am trying to visualize polygons by turning them into volumes (same shape at the base and roof, but with walls). I would then ...
1
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2answers
175 views

How to split a (road) buffer using the centerline?

I have a road centreline dataset which I have buffered using the road width. I used the standard QGIS buffer tool. I realise for my analysis I actually need to split the road buffer in half and ...
2
votes
1answer
327 views

How to undo misclicks while drawing a polygon?

I'm trying to draw some polygons in QGIS 2.2 and I lose it, because everytime I misclick, I don't find a way to undo that point and start drawing again. I'm sure there's a way. Does anyone know it?
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3answers
43 views

Adding combined footage to points from the beginning of a line

I'm trying to add the footage of each point from the beginning of the line to the end. There are around 4k vertexes between the two ends that I need to put the footage from the beginning of the line ...
1
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1answer
314 views

Reprojecting a raster DEM from meters to feet using QGIS?

Is there a tool in QGIS that does the same as reprojecting a raster DEM from meters to feet as in ArcGIS's 3D Analyst > Raster Math > Times ?
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2answers
235 views

How to make a routable graph from a Point and a Line shapefile, using Networkx?

I have one shapefile which consists of all the streets in the study area, and another shapefile which has points representing origins and destinations. I would like to know if it's possible to find ...
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0answers
14 views

QGIS DBmanager import file append not working [duplicate]

I am using QGIS and connecting to Postgresql database. I want to import shapefile data into database table via DBmanager tool. But Append data to table selection is inactive like following image. I ...
2
votes
1answer
67 views

Is there a way to clip a polygon layer according to DEM elevation?

I have a polygon layer on top of a DEM. Is there a way to clip the polygon layer according to elevation, ie the clipped result being only those areas of the polygon layer between x and y altitude? ...
0
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1answer
41 views

QGIS GRASS plugin: r.composite quality loss

When using the r.composite tool within the GRASS plugin in QGIS, the result raster has a cell size of 150x150 while the input rasters have a cellsize of 30x30. Can this be overcome somehow or is this ...
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0answers
44 views

QGIS Fill Ring tool problem

Using the new (in 2.2) 'Fill Ring' tool and it doesn't seem to work correctly in all cases. It seems that if I try and digitise the new ring close to the polygon boundary, TWO (or more) geometries ...
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0answers
31 views

what is the math behind rasterization? Doubt [duplicate]

In Figure 4 you can see how the overlap is not complete (marked with circles). What I would like to know which algorithm that QGIS uses the rasterization? What is your standard? Is there a percentage ...
3
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1answer
342 views

How to make a Python script that does a task in QGIS?

When I run this code in QGIS Python console it works fine, but I want want to run it from an external Python script. What I want the script to do is: 1- Open QGIS 2- Run this code 3- Close QGIS from ...
0
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1answer
99 views

qgis's georeferencer renders my white map with a translucent blue tint, can I prevent this?

I'm running QGIS 2.0.1-Dufour on MacOSX and when loading a PNG or TIFF into qgis as a raster its always getting rendered with a blue tint. Here's what it looks like before being loaded into QGis's ...
2
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0answers
153 views

PyQGIS: Programmatically Adding Point Features via QgsMapToolEmitPoint

I've created a map tool for QGIS 2.0 Python plugin that emits a point with the click of the mouse. I'm trying to create an edit tool, adding a point feature at the emitted point while selecting ...
3
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2answers
534 views

How to automatically draw lines with a given angle from one single point in qgis 1.8?

I'm new to qgis so please be patient. I need to draw a bundle of lines all originating from the same point and with a 10° angle between each line (e.g. lines bearing at 0,10,20 ..90..110..220..350). I ...
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2answers
49 views

error using the QGIS “terrain profile” plug in

I have searched the home page for the "terrain profile" tool but have not found why I am getting error when trying to utilize it. Any ideas? I have a polyline and 4 dems ready to run the tool. Would ...