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

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6
votes
2answers
129 views

How to calculate how many polygons I can put inside a polygon?

I usually use qgis. I explain my problem with an example: there is a forest (irregular geometry1 ) and one tree (geomery2). I want to know the maximum number of trees that the forest can contain. ...
1
vote
0answers
33 views

How to join weighted attribute from polygons to point

I would like to join attribute from polygons to green point. Are there some methods? Something like "weighted mean by distance" of attribute from polygons or else...
1
vote
1answer
15 views

Shortcut to display scale from cache in qgis print composter

Bit of a tricky question, not sure if this can be done. When loading a map in the print composer I always click on the main area where the map displays, then click on 'set to map canvas extent'. Then ...
1
vote
1answer
105 views

QGIS python script loop for raster calculator

How can I write a QGIS script for making a loop of raster calculator through a set of rasters? I know I can read multiple raster by applying: lddLrs = qgis.utils.iface.legendInterface().layers() for ...
2
votes
1answer
65 views

QGIS find and then replace value in multiple columns

This is based on a previous question/answer that I had. QGIS -replace values in multiple columns I need it to update 3 fields now and I get an name 'e' is not defined error. What have I done wrong? ...
2
votes
1answer
35 views

Converting NAD 83 State Plane Maryland Feet Coordinates from lat/long and vice versa using QGIS?

I need to convert a list of lat/lon points (in.csv file) into NAD 83 State Plane Maryland Feet and vice versa. I know it can be done using ArcGIS, but I only have QGIS. I am also quite new to ...
2
votes
1answer
45 views

Why is my attributes table greyed out for raster layers?

I am trying to view attribute data for a SRTM geotiff but for some reason I cant view the data.
1
vote
2answers
40 views

Making raster DEM from irregular points shapefile in QGIS?

I assume that first I need to interpolate and then somehow turn it into raster in QGIS?
3
votes
0answers
27 views

Why is the unique ID field in Distance matrix empty for some inputs?

I have some coordinates in a .TSV file I import using the delimited text layer button. I have a different set of coordinates (actually, one point) that I import in the same way. What I've tried so ...
1
vote
0answers
23 views

Missing vector features when import from .sqlite to postgis?

I imported vector data from a .sqlite file to PostGIS but not all of my vector features imported. I haven't been able to determine a reason for most of the loss of features between the databases ...
1
vote
2answers
36 views

Convert colum type in PostGiS via DB Manager/ SQL in QGIS

I have a csv file that I want to bring into a PostGIS database through DB Manager in QGIS. I have a column/ field called "Location" that contains geometry (e.g. (40.789423 -75.628493 ...
4
votes
2answers
78 views

Improve DTM under forested areas without smoothing?

I'm using a DTM retrieved from LiDAR data and I noticed that forested areas are grainy or not defined. The DTM data was retrieved from geostore.com. Here is one example: Is there any way to ...
3
votes
1answer
39 views

How can I make new QGIS projects use absolute path by default?

New QGIS projects are saved with relative path location for data sources by default. If you want to use absolute path, each time a new project is created, this setting needs to be changed in the ...
3
votes
1answer
16 views

georeferencing raster data with unknown CRS

I’m new to QGIS and georeferencing raster data. I have a raster dataset with unknown CRS. The coordinates for goerefencing the raster data with reference points (x = 589 Y = 1483 / x = 500 Y = 1500) ...
2
votes
1answer
28 views

Why is my legend in QGIS using cached data?

I have a legend... multiple legends as a matter of fact. Even though I clear them out and start from scratch, I am getting old cached data of what my color ranges used to be, instead of what they've ...
2
votes
2answers
32 views

How to (automatically) extract a substring from attribute table

I have an attribute table that contains in a field/slot called "Description" data like this: <b>xyz: 11.02.2016 04:05 - 14.02.2016 04:03</b><br/><br/>0 km/h, 0 hauk/min , ODO ...
1
vote
1answer
28 views

Calculate areas of overlapping polygons from two shapefiles

In Why does intersect not calculate polygon areas? the answer is "The area values in attribute table are just random attributes in the eyes of QGIS. It is therefore perfectly normal that these ...
1
vote
2answers
39 views

D3 can't render GeoJson file (Simple structure in Montreal, Canada) created in QGIS

I am attempting to render SVG and attach it to a div with id="map". I can do this successfully with GeoJson which I acquired from this tutorial: http://maptimeboston.github.io/d3-maptime/#/1 Excerpt: ...
1
vote
0answers
10 views

Create a script/tool to run Crystal Reports after a Geoprocessing step? [closed]

We currently provide Crystal reports to our clients that order data requests. I have automated some of the process, but is there a way to incorporate a script/tool/model that would then take my ...
1
vote
0answers
24 views

Clipping vector polygons by previous vector polygons in same layer in QGIS

I have extremely large datasets as vector polygons in single layers. The polygons are in an order. I want the previous ordered polygons to clip the later polygons. Therefore, once an area has been ...
1
vote
1answer
41 views

tiff to shapefile using GDAL - slow speed

I am converting a 500MB .tif file to .shp file using GDAL. I am using the following: gdal_polygonize.py .tiff file -f “ESRI Shapefile” out.shp However, I abandoned the first attempt as in 12hrs it ...
2
votes
2answers
39 views

How to access the result(s) of a Processing module?

I am experimenting with the QGis Processing toolbox. I open up the module dialogue, set it then parameters and click. If the run succeeds the dialogue is closed automatically and no result(s) are ever ...
1
vote
1answer
25 views

Compiling QGIS 2.14 32 bit with Visual Studio

I have two plugins for QGIS 2.8 32 bit until now compiled in Visual Studio 2008. Now I want to bring them up to QGIS 2.14 32 bit, but get error message in compiling because Error C2065: 'nullptr' ...
2
votes
0answers
26 views

Why aren't my integer columns available for graduated styling?

I have a layer with graduated styling based on an integer column. When I duplicate the layer to make a similar styling based on another integer column, none of the columns are available for graduated ...
3
votes
0answers
21 views

How to blend edges of aerial imagery with gdalwarp

I need to fade/blend the edges of a series of aerial images with gdal. The closest thing that I've been able to accomplish is using the -cutline and -cblend switches of gdalwarp to get the edges to ...
1
vote
0answers
23 views

Layer style is not rendered properly using PyQGIS

I'm trying to render a layer with the given .qml style into .png image using a standalone PyQGIS application. The issue is that not all the layers of the symbology are rendered, e.g. a polygon with ...
2
votes
1answer
48 views

What to do to keep Python code permanent in QGIS 2.14.2?

I have this code provided by @Joseph but lose it whenever I leave the QGIS and I have to load it on the Python Console whenever reopen QGIS. What to do to keep this code in a permanent way?
1
vote
1answer
23 views

How to copy the geometry WKT from a temporary scratch layer in QGIS?

It seems in the 2.14.2 version of QGIS the ability to copy the WKT from the geometry of a temporary scratch layer has been removed. Previously you could create, for example, a new polygon feature in ...
4
votes
0answers
65 views

Convert raster to smooth contour polygons in QGIS

I have had limited success creating smooth contour polygons from a raster layers. I have created contour lines and boundary polylines and then used QGIS Union. Then I use QGIS Polygonize. Then ...
1
vote
0answers
20 views

scale polygon in Qgis [duplicate]

The task is to scale a polygon in QGIS. The procedure is performed tracing the polygon and then apply a scaling factor ( the factor used is " Distance on the ground" / " Distance on map " ) . Both ...
2
votes
1answer
110 views

How to add a Mapinfo-style text halo in QGIS print composer?

Is there any way to imitate the Mapinfo halo (of something similar) in the Print Composer. I'm trying to put some text (copyright information) over the maps and I want to make it so that it is easier ...
0
votes
0answers
9 views

Allocating premises between postcode polygons and telephone exchange area polygons in QGIS?

I have telephone exchange areas as one polygon layer and postcode (codepoint) polygons as another. The postcode polygons have the number of premises in each postcode as a field. I want to estimate the ...
3
votes
1answer
60 views

How to calculate correct raster stats?

I've done a lot spatial analysis in ArcGIS. Then I decided to start to learn QGIS. I started with DEM analysis. But I found differences in statistics of DEM. ArcGIS correctly recognizes the lowest and ...
1
vote
0answers
19 views

Split polygon manually- geometry validity error problem

I want to split a polygon layer manually using the Split tool in QGIS however I'm getting an error no feature slit done: The geometry is invalid. Please repair before trying to split. I have ...
-1
votes
1answer
41 views

Calculation of coordinates

How can I merge some small regions to create big regions? Then how would I be able to calculate the coordinates of these new regions?
0
votes
0answers
35 views

Drawing contour with python QGIS?

I have one point layer and one contour layer and I was trying to draw a line around one contour, making a circle but not a uniform one, it has to have an irregular shape. I cannot find a tool that ...
2
votes
0answers
37 views

Between operator QGIS

I am using QGIS Essen version (2.14.1). I am trying to filter my data based on dates. I am wondering if the "between" operator exists like in SQL? I'm trying the following query but the results are ...
2
votes
0answers
14 views

downloading waypoint layer from garmin gps 60CSx to QGIS 1.8.0Lisboa

I want to download waypoint from my Garmin GPS but it responded the layer GPS.gpx?type=waypoint is not a valid layer and can not be added to the map whereas my colleagues do the same without ...
1
vote
0answers
23 views

Qgis gdalogr:contour is not generating output

I am trying to use gdal:contour script in Qgis console and then script. Here is code which I tried write to console. raster = QgsRasterLayer('C:/Users/Bulva.user/Desktop/test_raster.asc', "DEM") ...
5
votes
2answers
143 views

Smoothing method for big polygons

I'm looking for an alternative to 'snakes method' for smoothing very big polygons, which I created from SRTM elevation datasets. The problem is that the smoothing is getting stuck after a while with ...
2
votes
1answer
27 views

How to connect QgsMapLayerComboBox to QgsDataDefinedButton

in Qt Designer there is the possibility to use directly QGIS custom widgets. In the UI I added a QgsMapLayerComboBox (to get the layers added in the legend) and a QgsDataDefinedButton. What I would ...
3
votes
1answer
36 views

Get QgsField alias in QGIS Python

In QGIS Python, how to get alias of field. In class QgsField, i can not find method to do this. lay = iface.activeLayer() provider = lay.dataProvider() fields = provider.getFields() for field in ...
1
vote
1answer
36 views

Finding nearest point using point dataset using QGIS?

I have created Geocode for some area and I couldn't find accurate Geocode's for few address. so I want to find the nearest POI for non accurated locations using accurated geocodes as referece in QGIS. ...
0
votes
1answer
31 views

Can gdalwarp reproject from ESPG:4326 (WGS84) to UTM?

I've a GeoTIFF image in ESPG:4326 (WGS84) and when I try with gdalwarp to reproject to UTM, it has problem gdalwarp -s_srs "EPSG:4326" -t_srs '+proj=utm +zone=33 +datum=WGS84 +units=m +no_defs' -of ...
3
votes
0answers
24 views

Inputting Layers in QGIS for PyWPS Processes

I recently downloaded the PyWPS demo files from github here: https://github.com/PyWPS/pywps-4-demo. I'm having some trouble figuring out how to use some of the processes. In particular, processes like ...
4
votes
1answer
68 views

How to randomly position coordinates within a containing feature in QGIS?

I have geocoded address data, and I am wishing to randomly position it within the census tracts that they are in to obfuscate... So the points are still within the feature but randomly move around so ...
3
votes
1answer
31 views

Performing least cost path analysis on QGIS using permeability scores for 60 points in network?

I have a map that is made up of polygons that apparently cover the whole area without leaving gaps, each representing a field, a wood, a road, a house etc. Each polygon has a score in the attributes ...
4
votes
3answers
72 views

Issues in Intersecting Voronoi Polygons With Other Boundary Shapes (QGIS)

I'm having problems in intersecting Voronoi polygons with another shape. As the image shows, I want to clip the Voronoi layer at the red costal perimeter of the UK so that the additional surface area ...
2
votes
1answer
37 views

Installing qgis-ltr or qgis-ltr-full with OSGeo4W or both?

I need some help with the installation of QGIS using OSGeo4W. I am using windows 7 and I want to install a 64 bit ltr release with all relevant dependencies and plugins. I choose to install qgis with ...
2
votes
1answer
41 views

How to get mean coordinates of features from a point layer?

I have a vector layer containing several points and I would like to generate the mean coordinates of these points, using QGIS only if possible. I'm looking for something similar to centroids, but for ...