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

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-1
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0answers
6 views

c++ qgisvector layer is not Valid

#include <QtCore> #include <QApplication> #include <QWidget> #include <qgsapplication.h> #include <QMainWindow> #include <qgsmapcanvas.h> #include ...
1
vote
1answer
18 views

Route and distance measuring

I'm looking for a plugin that can make a route from given GPS points and then calculate the distance of this route. I'm going to create GPS points and import it to Qgis as a GPX file. I know I can ...
1
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0answers
35 views

Create floorplan KML file in QGIS?

I import a building floor plan from DXF format to QGIS. When I export it to KML format and then import it in Google Earth, how can I put the floor plan to my desire building location? MY CRS is WSG84 ...
0
votes
0answers
10 views

Finding and using data on population density files

I'm new to GIS and been trying to figure so many things out on my own by using QGIS. Now on to my question. I'm attempting to replicate this map for the state of Nevada: ...
1
vote
1answer
666 views

Import SketchUp created KML contour lines model to QGIS

There's a neat trick to create contour lines based on the GE 3D terrain using Sketch-Up. The resulting KML however is a model I have looked at ways of importing KML layers to QGIS, like it was ...
1
vote
2answers
83 views

QGIS OpenLayers Google Maps not zooming

Google Satellite will not zoom. Although the scale changes as I zoom, as the map is re-rendered, it zooms out to its maximum extent every time. This first happened in the latter part of November ...
1
vote
0answers
13 views

how to automatically update column based on the second layer, trigger, postgreSQL

I am newbie in postgreSQL. I have 2 tables, observation and landcover, i want to create a trigger which would allowed to update the column observation.land based on the spatial information according ...
2
votes
0answers
17 views

Help getting a Mathematical Representation within a Layer's Attribute Table

I'v been playing around with Vector Coding and was wondering if there was any Plugins out there that might let me represent Vectors within a layer as it's Mathematic attributes in the Layer's ...
2
votes
1answer
166 views

QGIS Python Labelling [on hold]

i want to label a point layer with those values exceeding a set of variables attribute table as follows 'loc field'(text),'a'(float),'b'(float),'c'(float) variables as follows vara = 5, varb = 3, ...
0
votes
1answer
199 views

QGIS 2.0 Howto copy raster data from a QgsRasterDataProvider to an OpenCV matrix

I'm hacking the half day arround a problem and that I' thought it was simple one. I'm using C++ (QtCreator) QGIS 2.0 und openCV2 on an 64 bit Workstation runnig Debian Wheezy. The Application I try to ...
10
votes
2answers
603 views

How to link dataframes in ArcGIS or QGIS?

The below image shows a layout in ArcGIS 10.1 with four dataframes. Each dataframe is of the same geographic area, although they are different images. For example, the top left image is a 1989 DOQ, ...
1
vote
1answer
251 views

query / filter on attribute tables with external tables joined

i tried to do some queries on joiend table fields ... i've got/found some answers concerning version 1.8 - which result in "use select + export to create a combined dataset" so i just did some tests ...
4
votes
2answers
447 views

Load and display a layer using PYQGIS

I'm having a go at using pyqgis from within the QGIS python console to load a layer from SQL Server and display it. I feel like I'm part way there but I'm having a real issue getting the layer to ...
3
votes
3answers
276 views

How to calculate peaks in a DEM

How could I extract all peaks from a DEM (large mountainous area)? Peak means something like: a pixel which is sourrounded by other pixels with smaler elevation numbers in a area arround the ...
-1
votes
0answers
27 views

Split polygon based on line qgis [on hold]

I would like to split polygons based on intersection of a polyline. How can i do this with python in QGIS? Thanks
0
votes
0answers
40 views

QGIS- Unable to load GdalTools plugin

When I start QGIS, it display error message: Unable to load GdalTools plugin. The required "osgeo [python-gdal]" module is missing. Install it and try again. Couldn't load plugin 'processing' from ...
-1
votes
2answers
47 views

File or personal database in qgis?

is there any database ? I use ArcMap with file geodatabase. But now, i have make project in qgis and i dont know, how to create database.
1
vote
2answers
133 views

render geotiff tiles as a map layer

i have the following problem: i have downloaded tiff files with gMapMaker and transformed them to GeoTiff using the associated .map files in QGIS. now i want to render these GeoTiff files to use them ...
0
votes
0answers
23 views

What am I doing wrong with QGIS v.clean?

I thought I understood how the GRASS v.clean tool worked in QGIS (in 2.6.1 Brighton) but I keep getting unexpected results and errors with a polygon ShapeFile. I've run the QGIS TopologyChecker with ...
1
vote
2answers
19 views

QComboBox nested within a Qmenu?

Is it possible to nest a QComboBox inside of a Qmenu within QGIS? Below is my current code and an associated screenshot with the unexpected results. (orange = current incorrect placement, green = ...
1
vote
1answer
41 views

How to split a text attribute by characters in QGIS 2.6.0

Is it possible to make a new column, for example named "Test" and store the first part of the column "Name" split by -? See below how it should look like:
1
vote
0answers
30 views

Assessing Flood Hazard Risk Zones using DEM

My Question: What is the best effective way to quickly estimate flood hazard risk areas using DEM data? Ideally I am looking for guidance to move forward and perform this process over large areas ...
2
votes
1answer
35 views

Models -> [Example Models] -> Contour lines from points: on MAC

I'm running QGIS2.6 on a Mac and can't seem to locate the "Contour Lines from Points" Example Model. Any help would be appreciated. SAGA is installed.
22
votes
5answers
2k views
+100

How to generalize a polygon file and maintain topology in QGIS?

I have a polygon Shapefile, which I need to generalize. How can I generalize the poligons and ensure that there are no topological errors like "slivers". I already tried: Vector -> Geometry Tools ...
1
vote
0answers
16 views

Syntax to use when entering geographic data into geography columns via SQLSERVER Management Studio

I am starting to learn about spatially aware databases. I have QGIS 2.61 and SQLserver express 2012. I can set up a table using the SQL Server Management studio GUI and insert a geography column. ...
3
votes
0answers
28 views

Merge Raster Layer Specific Order in Graphic Modeler

I'm using the Graphic Modeler/Processing Modeler to automate a process. The last step in this process is Merging three different Raster Layers. I'm using the "Merge Raster Layers" from Saga 2.0.8. ...
2
votes
1answer
30 views

QGIS has an automatic way of finding the LS factor?

I wonder if is possible to calculate LS (soil erosion) factor automatically in QGIS? Or at least a way to calculate the length slope?
1
vote
1answer
16 views

QGIS plugin select and edit features performance issues

I wrote a plugin for selecting and instant updating the value of the selected feature in the attribute table. I tested with a big shapefile and to select and edit 5 features takes ~5 seconds. Which ...
3
votes
1answer
30 views

Change no-data pixel value in raster: QGIS 2.6

I want to change the value in all pixels that are currently 0 to 800 in QGIS 2.6.1. 0 is listed as the no-data value in Properties > Transparency. I have unchecked the No Data Value box there. Then I ...
1
vote
1answer
44 views

What is a memory vector layer in QGIS?

What is a memory vector layer and how does it relate to the vector layer? Background info: I have a volunteer working with my organization, because of financial reasons we have him using QGIS. He ...
8
votes
3answers
140 views

Calculating all distances from single points to multiple polygons

I have two layers: a point layer defining properties (95 objects), and a polygon layer defining plots of land associated with the properties (211 objects). Each point relates to one or more polygons. ...
1
vote
1answer
22 views

Adding shapefile layers in QGIS causes previous layers to disappear

This is my first time having such trouble, but I'm only a casual user. I have a base raster layer of the school I work for and I've been adding vector shapefiles on top of that in separate ...
5
votes
1answer
254 views

Calculating Topographic Exposure with Raster Calculator

I need you help trying to calculate Topographic Exposure (TOPEX) on a DEM in ArcGIS. I am trying to figure out wind exposure on a DEM with 25m cells. There is a great blog post where someone explains ...
2
votes
1answer
19 views

Plugin to develop composer attribute tables

I have no experience of plugin development, but I'm wondering if it would be possible to write a plugin that solved the issue of multi-line tables in print composer http://hub.qgis.org/issues/10273 I ...
8
votes
2answers
459 views

Finding polygons without right angles using Open Source GIS or ArcGIS for Desktop?

Now we are digitizing some buildings in specified area. The obligatory rule for this work - in most cases buildings should have right angles. We are using QGIS with CAD tools for this work but ...
0
votes
2answers
140 views

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

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
vote
0answers
16 views

qgis & wacom cintiq stream digitizing

How to digitize in stream mode in Qgis, using a wacom cintiq tablet? freehand it's no use. i need something like MNDR stream digitizing extension for arcview 3.x, which allows continuous tracing, ...
3
votes
2answers
44 views

Azimuthal orthographic projection QGIS2.6

I'm trying to create a globe view in QGIS2.6 with an Azimuthal Orthographic projection using NaturalEarth's 110m countries dataset. I'm following Hamish Campbell's blog post instructions that have ...
1
vote
0answers
16 views

Projection problems when importing .kml from Google Earth to QGIS

I want to open several points that I exported from Google Earth as a .kml in QGIS for further use. I can import the data and the points are displayed but something must be wrong with the projection as ...
1
vote
0answers
46 views

Can't install QGIS 2.6.0 need SQlite3 on OSX Yosemite

I need to install QGIS on my mac with 10.10 Yosemite, I have already installed: - SQLite3_Framework-3.8.7.3 - GDAL_Framework-1.11.1-2 - GSL_Framework-1.16-1 - NumPy-1.8.0-1 but when I launch QGIS.pkg ...
1
vote
4answers
614 views

Why does QGIS not detect the CSV/DBF column headers?

I am trying to import a csv or dbf into qGIS so I can perform a join on a shapefile. However, qGIS is not detecting the first row as header names. I know I've done similar joins before and there's ...
2
votes
1answer
26 views

Information On Supported Device Qgis Galaxy Tab 4 10.1 4G LTE

I need a tablet for outdoor work and i would know if this device "Samsung Galaxy Tab 4 10.1 4G LTE" works fine with qGis mobile application.
1
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0answers
12 views

plugin compile with make would not compile module [on hold]

Ubuntu 14.04 QGIS 2.6 PyQt4 I'm following one of many tutorials on 'plugin builder', here is the latest one I'm trying with: http://www.digital-geography.com/build-qgis-plugin/ It all seems very ...
1
vote
0answers
27 views

Join/convert points to polygons

(I am using QGIS 2.6 Brighton) I have 2 shps, one points and another one polygons. I need to make them one. Is there a way to join them or convert the points to polygons? Vonoroi doesnt work for me ...
1
vote
1answer
19 views

creating a new vector layer from a part of the current one [duplicate]

I am using qgis 2.6 for the first time. As I was using 2.2 previously, it was easy for me to create a new vector layer from a part of the current layer with the help of option "save selection as a new ...
1
vote
1answer
202 views

Adding MrSid to QGIS

I'm fairly new to QGIS and was hoping someone could help me load some MrSID photos into QGIS. I have read some posts and have installed the OSGEO4W Installer and selected the GDAL-MRSID Lib. I ...
1
vote
1answer
21 views

78% cease calculation and “no message” from QGIS

I'm a total noob. I'm trying to generate an outline of a bunch of elevation lines which i can use to cut into some other elevation lines. I understand that I can buffer and dissolve to get the result ...
2
votes
0answers
32 views

Frontal Detection of sst & Chlorophyll image

I am working on sea surface temperature satellite images and looking for delineating gradients in open source on the basis of temperature. Is there any tool like Cayula and Cornillon front detection ...
1
vote
1answer
126 views

QGIS Print Composer with ESPG:32615 [on hold]

I have imported a PostGIS layer as the only object into my project and set the project and layer CRS to EPSG:32615 (UTM Zone 15N). My layer appears just fine in the work area. When I try to create a ...
2
votes
1answer
61 views

PostGIS cannot create new feature

I have a PostGIS database - using the main user I can create/update new features no worries. I have created a series of new logins and given them all full access to select/insert/update etc all the ...