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

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2
votes
1answer
27 views

Generate a raster with a uniform value using QGis

I'm working on a project using the qgis-modeler and i want generate a raster with a uniform value. i'm using r.surf.random function of GRASS which need min and max value but i want have only one ...
1
vote
1answer
24 views

I want to compare multiple raster layers against each other to identify changes in pixel values over time

I am using LAI values to assess vegetation growth over large areas. I want to be able to identify areas that are doing well and areas that are decreasing based on the changes in pixel values. Ideally ...
4
votes
0answers
62 views

QGIS and the South Pole: bug or feature?

I am trying to work with some data from Antarctica in QGIS. I have defined this new projection: +proj=laea +lat_0=-90 +lon_0=0 +datum=WGS84 +units=m +no_defs And started adding a few vector layers. ...
0
votes
1answer
22 views

Radiometric Indices error

I have successfully included otbApplicaton in my python code. Tested the otb inclusion it is working fine. I am using the following code to generate NDVI output from the landsat image. from sys ...
1
vote
1answer
113 views

qgis refresh button for attributeactions

QgsVectorLayer* vLyr=static_cast<QgsVectorLayer*>(aktLayer->qgsLayer); vLyr->actions()->addAction(QgsAction::ActionType::OpenUrl, "Link im Webbrowser öffnen", "[% "+sAttribute+" %]" , ...
2
votes
1answer
32 views

How to update a column in a layer with NULL currently to nearby value in QGIS?

Currently I have a layer with construction year attributes in it. Not all of these are filled out and I figure it is reasonable to update them with the construction year of the nearby elements as they ...
0
votes
0answers
18 views

How can I create a warp mesh to match two close but not identical datasets together?

I have two datasets for Mars. One of them is the Mars Viking color mosaic, the other the Mars Global Surveyor black and white imagery. When I overlay the two datasets, it becomes obvious that the ...
3
votes
1answer
57 views

Misalignment of EPSG:4326 and EPSG:3399 coordinates

I'm having a QGIS project in local coordinates (Gauss-Kruger, EPSG:3399) with some layers in the same reference system. On top of that, I want to display point coordinates, which I digitized using ...
0
votes
1answer
26 views

Problem calling qgis2leaf outside the QGIS

I am a computer programmer starting with PyqGis-Python, and I’d need to automatize the creation of a webmap using the plugin of qgis2leaf from a QGIS Project. I have reached to call “import ...
3
votes
3answers
97 views

Is it possible to perform automatic snapping of polygons in QGIS or ArcGIS?

Note: in the picture below white space between the polygons is blank space – it does not contain any polygons as a result of Intersect or Union functions.
1
vote
0answers
26 views

qgis Points data from KML file

Forgive me if this question has been asked before. My search of the site did not turn up anything relevant, so I decided to ask this question. I have a KML file with Waypoints and several Tracks in ...
0
votes
0answers
18 views

Multi Label with Multi Placement

is there any way to add multiple label at different placement in qgis. Suppose I have a vector layer for line geometry and my attribute are name and route number. Now i want to add the route number to ...
2
votes
2answers
108 views

How to use `layer.getFeatures()` in a standalone script?

I am following the QGIS Cookbook and this post where it concerns reading attributes from layers. I would like to exploit this method and implement it into a standalone script. Essentially, I want to ...
0
votes
0answers
17 views

Error in projection Qgis [duplicate]

qGIS- when I try to project using +proj=robin +lon_0=-150 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs In order to centre on the Pacific I get this: Any advice? Thank you!
1
vote
0answers
47 views

How can I export symbology and labels with QGIS Leaflet to webmap?

If I make a map in QGIS export it with Leaflet the symbology and labels don't appear on the webmap. Is it possible to export them? If yes, how to export the all map?
2
votes
1answer
43 views

use gdal python bindings from the QGIS folder in a custom script

I have QGIS installed (on Windows) and can import this line from the QGIS Python console: from osgeo import gdal When I try the import in a python file it doesn't work Traceback (most recent call ...
0
votes
1answer
43 views

Resolution problem

I have a Landsat TM image and in QGIS I used Clipper to crop my image. Then, I tried to reprojected it via Warp (Reproject) and the pixel size goes 29.9936,-29.9936. I do not understand why this ...
2
votes
2answers
40 views

Change line into multiple segments where they overlap with nodes and vertex (qgis)

I have one (very) long line (e.g. line 2) I also have another line (line 3) which nodes are snapped with two vertexes of line 2. I want to break line 2 up in three segments. Is this possible by using ...
2
votes
0answers
22 views

Error while loading shared libraries libqgis_core.2.9.0

I have complied QGIS version 2.8.1 from source, according to the instructions from https://github.com/qgis/QGIS/blob/master/INSTALL Now after successfully running ccmake .., make and make install ...
-3
votes
2answers
53 views

Fractional Area Calculation

I have a file (in both raster and vector) of different districts in a country. I have also made a grid of 1 deg * 1 deg (both vector and raster) of the country. I want to calculate the area of each ...
0
votes
0answers
19 views

Grouping layers in QGIS? [duplicate]

I'm trying to group a large amount of layers together. They are a mix of Polygons and Points, I would like to create individual groups by the layer's name. Anyone have any ideas?
3
votes
2answers
77 views

Can't export customer's shapefile to latitude and longitude

I'm very new to this application so bear with me. I hope that I am missing something very elementary. I have a shapefile supplied by my customer. I need to get the latitude and longitude for each ...
1
vote
0answers
32 views

Gradient fill based on scores (similar to elevation)

I'm rather new to using GIS (QGIS, specifically). I've mapped out a cohort of around 550 patients across Long Island, New York based on their full address by using MMQGIS plugin. This data is ...
0
votes
0answers
27 views

Creating slippy map from large shapefiles?

I am trying to create a map of the UK based on a number of open data sources (Ordnance Survey Open Data, OSM, some CSV files etc). My end goal is to create a map of the whole of the UK that I can ...
0
votes
0answers
42 views

Making QGIS custom form modal?

I have created a custom form for entering attribute values for newly added features / editing attribute values for existing features of a shape file. I chose the ui file as "Edit UI" and a python file ...
0
votes
0answers
17 views

How to use cx_Oracle db connection with OGR API

I am creating ogr datasource for oracle spatial using OCI connection in pyton code successfully. I can also get the layer from the datasource and I can add new features. But I am also using ...
4
votes
2answers
110 views

How to digitize building footprints with orthogonal edges?

Using QGIS, I am trying to digitize an old raster map, and because I ultimately want to load these 2d layers into sketch-up to turn into 3D models, I need everything to be square. Here's a sample of ...
1
vote
0answers
87 views

ECW support for QGIS 2.8 (Wien) and Ubuntu 14.10 (Utopic Unicorn)

Getting QGIS 2.8 (Ubuntu 14.10) ready for ECW files is really a pain. I've no terminal experience and it took me several hours to install the ECW JPEG 2000 SDK 3.3. What I did so far: #download ECW ...
3
votes
2answers
119 views

How to add a legend to a canvas in a standalone PyQGIS application?

I am trying to develop a standalone PyQGIS application. The map display does not pose any problems, but I do not know how to add a legend to the canvas.
3
votes
3answers
121 views

Which UTM zone to use for a large country?

I want to reproject OpenStreetMap roads data from the current projection (WGS 84) to UTM, since I read in another GIS.SE discussion (How to get $length in meters in QGIS?) that WGS 84 cannot be used ...
0
votes
1answer
55 views

Converting .ecw to .jp2

Is there any easy to use software for converting .ecw/.eww files to .jp2/.jpw files without loosing the georeferencing? I don't want to use proprietary file formats with QGIS. EDIT: I've deleted the ...
1
vote
1answer
48 views

How can I get features that satisfy a QgsExpression using PyQGIS?

I have two fields say "State" and "name" which would be get from the two comboboxes. After which, based on the current text in the combo box, I want to make QgsExpression and feature that satisfies ...
0
votes
1answer
43 views

How to access shapefile m-values with pyqgis?

Does anyone know how to access (read/write) m-values of a line-shapefile using pyqgis? I know how to do it with arcpy cursors ...
0
votes
1answer
16 views

How to convert a specific multipolygon to minimum polygons

I've got this kml file with one multipolygon inside. A link for the file are here multipolygon.zip My goal is to get a multipolygon with the minimum count of polygons with only outer border and ...
1
vote
0answers
55 views

Problems installing QGIS 2.8 Wien on Windows 7

Having trouble upgrading from QGIS 1.8, which ran just fine, to QGIS 2.8. I'm running 64-bit Windows 7. After uninstalling QGIS 1.8, I've been trying for several days to install the 32-bit version of ...
1
vote
2answers
109 views

Having trouble matching up U.S. Census shapefiles in QGIS

I'm trying to use the U.S. Census shapefiles to figure out what census blocks make up which state legislative districts. I decided to test the method on a state where I already had this data to see if ...
0
votes
0answers
28 views

Is PyQt4 'drag and drop' functionality available in Qgis Plugins?

In Qgis 2.8, is it possible to use the PyQt4 drag and drop classes (dragEnterEvent, dropEvent) to interact with items from a qtreeview, in a Python Plugin? Is it possible to hook into the ...
1
vote
1answer
66 views

QGIS custom Form - How to bind a value from a QComboBox?

I am trying to build a custom form for field data collection (bird species) with some python logic. The python code inserts values into a QComboBox: At the beginning of the list it adds the twenty ...
1
vote
1answer
36 views

How to implement Add feature action from PyQGIS

I'm trying to implement / reuse Add Feature functionality in my python plugin. there a class/function that handles geometry creation on canvas based on layer geometry definition? I'm checking API but ...
2
votes
2answers
49 views

Placement for Label

Is there I can define expression for the placement of label in vector layer like when the scale is less than x label placement should be curved else it should be horizontal. I am using Pal setting. I ...
2
votes
1answer
99 views

How is QGIS opening a shapefile with no *.prj file?

I was wondering how QGIS could open a shapefile with no *.prj file (for instance, let's say we have a shapefile with just *.shp, *.dbf and *.shx files). If the On the fly reprojection option is ...
1
vote
0answers
22 views

Where does GEOS Library gets installed QGis

Working on OS X 10.10, QGis 2.8 I want to install basemap. I installed QGis 2.8 which includes the GEOS and the PROJ4 library. In order to install basemap properly, I need to pinpoint it to the ...
1
vote
1answer
34 views

Converting integer value to unicode for labeling in QGIS

It is possible to stylize a layer with integer numbers stored in a shapefile and then choose a symbol out of a font. I would like to use the label engine instead, because i'm more flexible, for ...
1
vote
1answer
50 views

Old question without answer: R.Neighbors with large neighborhoods?

I'm working on the same theme as User 32882, and I'm new here. I have the same problem, and update his question with more details. Old question: "I'm running into problems running the r.neighbors ...
1
vote
2answers
47 views

multi-sheet printing of large-scale maps

Mapping a specific region at a larger scale, this region does not fit onto a single sheet of paper. For example mapping Austria at 1: 1 mio needs three sheets of din a4 paper. Question: Can I do ...
0
votes
1answer
43 views

cross referencing files question

This may be an easy question so please forgive me if it is (or if it makes no sense) as this is all very new to me. I have 3 files that I am trying to cross reference. One file has columns category, ...
2
votes
1answer
41 views

How to save .shp with layers 'baked' in with QGIS

I'm having no problem applying labels to the shapefile I'm working on in QGIS, but I can't seem to save the new shapefile with the layers 'baked in' for uploading to Mapbox, and then styling. I've ...
0
votes
2answers
32 views

Geoserver WFS-T not saving edits from QGIS to MS SQL layer

I added a MS SQL layer from my Geoserver to QGIS. It will save changes for attributes in the table and it will save the file if I delete features. However, if I add a feature or change a feature, it ...
0
votes
1answer
37 views

Conditional calculation - QGIS Raster Calculator or GRASS r.mapcalculator

Is it possible in QGIS either directly or via plugins to do a raster calculation including an if statement? e.g., if raster1 > 0.3, then raster 1 * raster 2, else raster1 x raster3...something like ...
2
votes
1answer
33 views

How to add a VFR map coordinate grid in QGIS?

I want to add a coordinate grid like in the link below to my map. A simple grid is no problem, but I would like to know how to add the fragmentation of the lines.