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

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9
votes
1answer
785 views

How to auto-generate map images with different styles in QGIS?

I have got a simple map in QGIS, containing only 1 layer which consists of 10+ features. Now I need to (programmatically) generate about 200 different JPEG map images of the same area. Each map should ...
2
votes
1answer
121 views

Get feature data from lat long input QGIS

In QGIS, I have a polygon dataset with feature data. I would like to extract data from this dataset using a latitude and longitude. To be more clear, I have a list of 1000 coordinates. I would like ...
1
vote
1answer
553 views

QGIS Python - Convert the CRS of an in memory vector layer

In a python script of qgis I load layers from different datasources using the QgsVectorLayer() and the QgsRasterLayer() commands. The coordinate reference systems of the data sources differs. Since I ...
2
votes
1answer
254 views

QGIS 2.4 Heatmap Plugin Generates a Solid Black Map

I'm trying to generate a heatmap of vehicle-pedestrian collisions in Los Angeles using data taken from UC Berekely TIMS. TIMS provides an exhaustive database of traffic accidents involving injury in ...
0
votes
2answers
166 views

How can I efficiently divide a KML file by area, while using ogr2ogr?

I have a work process which uses an ogr2ogr text command to convert a MapInfo TAB file to a KML file. I'm very pleased with this because it maintains the original symbology (a simple 2 colour system ...
0
votes
1answer
923 views

Determining the slope of a DEM (SRTM-data) in QGIS

I'm new to QGIS and I have to calculate the slope of a DEM (I use srtm-data). I already detected the geoalgorithms toolbox and I also produced a raster layer with the slope using the tool "slope, ...
1
vote
2answers
85 views

Creating a plugin tutorial

I am looking for a tutorial of how to create a plugin for QGIS. I want a tutorial that: Explains about the latest version of QGIS Working in windows environment. adequate for absolute beginners and ...
1
vote
1answer
266 views

Problem with projection of Slovenian Shapefile in QGIS

I hope someone can help me for this: I'm doing my masters thesis in Slovenia (in the field of wildlife management), for this I got a Shapefile of slovenian data by the University. As a main layer, I ...
1
vote
0answers
42 views

New sound when running QGIS 2.4 [duplicate]

I used QGIS for a very long time. In the last version, there seems be a new sound (buzz) when the program is run. Does anybody know how we can remove this sound?
1
vote
1answer
158 views

Error importing raster into GRASS plugin in QGIS

I am trying to import a tiff raster file into GRASS however every time I do this the below error message comes up. I am using a custom CRS so I have tried changing it back to the default CRS but still ...
3
votes
2answers
131 views

Distance from centre point to other points using QGIS?

I have a question of something I actually thought was pretty simple...I have a few points around a centre point. Now I want to know the distance from each point to the centre point. Is it possible to ...
1
vote
1answer
98 views

Setting resolution for GRASS raster

I am trying to calculate volume using the GRASSplugin. I have my area information in vector format and my depth information in raster. I read that it is important to set the raster resolution before ...
2
votes
3answers
465 views

Saving project from QGIS to CD so it can be used on other computers?

For purpose of a project, I created a project in QGIS - aerophoto base and 3 layers. It works perfect on my computer, but if I save it on CD, the project doesent work on any other computer... I saved ...
3
votes
3answers
182 views

How to divide attribute table in map composer between 2 or more pages?

Does anyone know how to divide attribute table between 2 or more pages? In exported PDF it's unfortunately clipped.
3
votes
1answer
135 views

How to change the color of vector layer of QGIS in api?

I'm using QGIS-2.4.0 api to develop app in C++. When I add a vector layer to the app, the vector map's color would be random. I used QgsFeatureRendererV2 to get the geometry type of the layer, my ...
1
vote
1answer
237 views

QGIS Web Client zoom and scale

I have a problem with setting up zoom levels and max/min scale in QGIS web client. It looks like that values used in GlobalOptions.js file does not apply. Right now ZOOM_LEVELS is 70, maxScale 50 and ...
3
votes
1answer
233 views

QGIS 2.4.0: dissolve tool renders artifacts / errors

The dissolve tool (vector>geoprocessing tools>dissolve) renders some artifacts on shapes with high number of polygons. I’m using a shapefile with 3222 polygons and I’m trying to dissolve it using the ...
2
votes
2answers
2k views

How to display distance in meters (km) and not in Decimal Degrees in QGIS 2.4?

I am a GIS beginner, and I have a question about how to get the distance between two points in meters instead of decimal degree. In QGIS 2.4 I have a project with two point layers (in WGS84). From ...
2
votes
1answer
68 views

QGIS vector layers do not match DEM?

I have a DEM (saved as a .tif) and, using QGIS, I want to clip the DEM using a vector mask. The function will not work. Am I missing critical step?
2
votes
2answers
127 views

Can GDAL fill elevation below a certain value?

I have several GeoTIFFs that I'm working with to create contours using gdal_contour. One of them crashes the utility. gdalinfo tells me that the computed min values for band 1 and 2 are -...
2
votes
1answer
544 views

Creating a World Population Density Map

I am trying to make a world population density Choropleth map (country level). The data I am using is publicly available on World Development Indicators website. Pretty much, I have an excel file ...
5
votes
1answer
324 views

Is there touch screen support in QGIS for Windows?

I have a new 2in1 PC (laptop and tablet). It would be very nice to navigate in QGIS using its touch screen I.e. zoom in and zoom out using double finger touch, like on a mobile phone, etc. Maybe ...
3
votes
4answers
291 views

QGIS Plugin with save settings dialog

I am writing on an update of the qgis2leaf plugin. It would be great to store the settings of the plugin UI (like which checkboxes are checked, which strings are used) in a separate file (like xml or ...
1
vote
0answers
226 views

Vector points from csv file wrong location in QGIS

I am using QGIS 1.8 (I know old version), and uploaded a csv file with coordinates. The underlying basemap is from Google, using the Open layers plugin. This basemap uses WGS84-epsg3857, and my vector ...
2
votes
2answers
447 views

QGIS installation from OSGeoW4: entry point not found in qgis_core.dll

I have installed QGIS through OSGeo4W installation. My operation system is windows 7 64x. I try to start the program QGIS Desktop from start menu this error: Do I need to do something? Installation ...
0
votes
1answer
114 views

QGIS 2.4 mapRenderer.extent() does not equal mapRenderer.setExtent()

Could anyone help explain this QGIS 2.4 python console code? I would expect the return value of .extent() to be the same as the bounding box given to .setExtent(): mapRenderer = iface.mapCanvas()....
2
votes
3answers
4k views

Saving selection as new shapefile using QGIS gives OGR error?

I have an issue saving a set of polygons as a new layer that I've selected using the polygon select tool in QGIS. After selecting the polygons in the main (source) layer, I've tried two ways: I ...
5
votes
2answers
370 views

What's the most efficient way to load feature attributes into a numpy array?

I am currently working on an add-on that relies on the user choosing fields of tables (that can be from shapefiles, csv or dbf) that are open in QGIS and then making computations with such data. ...
2
votes
1answer
684 views

Combine two grids with a small area of overlapping pixels to a new raster in QGIS/SAGA

The first grid is 1 byte and the second is 2 byte. The new raster should have a blended transition. How can i do this?
1
vote
1answer
124 views

How to simplify a multiline geometry in QGIS?

I'm trying to simplify my shapefile, which uses a lot of vertices to represent curvatures, by using the Generalizer plugin. But no matter what threshold I use for Douglas algorithm, it still includes ...
1
vote
3answers
252 views

Why do I get an error message at QGIS training manual 3.3?

I have a problem following the QGIS training manual lesson 3.3 (Ratio Classification). You have to add a column to an SQlite layer. The new column is AREA. I followed the instructions and added it as ...
1
vote
1answer
374 views

Difference between source SRS and target SRS in Raster Warp function

Hello I am trying to change a raster layer projections from WGS84 to a custom Lambert layer using 'Raster' --> 'Projections' --> 'Warp' function. I have been asked for source SRS and get SRS. what is ...
1
vote
1answer
903 views

Extracting raster values with polylines in QGIS

I have a polyline shapefile that represent a road an a raster grid with slope values. Is it possible to interpolate the shape file and the grid to have the average slope of the road? I know that I can ...
0
votes
1answer
228 views

CRS of QGIS bounding boxes [duplicate]

I used QGIS to find the extents/bounding boxes of a list of features from census data. I used the following method: Vector - Research tools - Polygon From Layer Extent, which creates a new shapefile ...
1
vote
1answer
140 views

cannot split a line using QgsGeometry.splitGeometry in QGIS

I create a new qgis file and run the following code. # create a line line = QgsFeature() line.setGeometry(QgsGeometry.fromPolyline([QgsPoint(50,50), QgsPoint(10,10)])) # create a layer layer = ...
0
votes
1answer
390 views

Determining unknown Coordinate System using QGIS?

I'm trying to figure out the coordinate system of some data I downloaded from a no-longer-maintained USDA website. The data's still accurate, it's just floating in space. I've tried several state-...
0
votes
0answers
192 views

What happened with NVIZ?

I'm unable to find and run NVIZ and now I've read several places that it's not functioning in the latest versions of QGIS? Is this a temporarily bug or definite?
5
votes
0answers
101 views

Resampling air temperature gridded data to sub-grid resolution

I'd like to obtain a 30-m resolution gridded dataset of air temperature from the ~1km gridded data of WorldClim, of Hijmans et al., 2005) for a mountainous region. The easiest procedure (I thought ...
2
votes
0answers
118 views

How can I store height info from GPS in QGIS?

I want to use QGIS as a tool for collecting GPS-Data in the field. One use case would be simple surevy tasks where I want to store the three dimensional position of points. QGIS is working fine on the ...
0
votes
1answer
177 views

How to manage two map items in a QGIS composition with python?

I need to manage two different map items in the same map composition, with a stand alone python script. Each composer map has been referenced like this: composerMap1 = composition.getComposerMapById(...
1
vote
0answers
143 views

Problem Installing QGIS to Samsung Galaxy Tab3

I try to install stable and nightly(18/09/2014 last nightly) versions of QGIS to Samsung Galaxy Tab3 (Android) but unfortunately I can't. When the installation is completed asked me to confirm the ...
1
vote
1answer
60 views

Help request fixing map errors in QGIS 2.4

Background: I am currently working on a project that requires me to translate shape files into geojson format and then upload them into MongoDB. There is a problem with MongoDB that prevents it from ...
1
vote
1answer
59 views

Why am I getting small float numbers when aggregating points containing large integer values in QGIS?

I have a layer of points containing the centroids of European NUTS regions at NUTS 3, with population data in the atttribute table. I want to aggregate this population data to NUTS level 1, which is ...
2
votes
2answers
256 views

Multiple font markers in shapefiles in QGIS?

I'm making a UK phase 1 vegetation survey map and require to show the dominant plant species in a given polygon. In phase 1 these are shown as 2- or 3-letter codes e g Ri, Cys. These codes need to ...
4
votes
2answers
276 views

How to get into the Python API of QGIS?

After a few hours I am about to give up on finding a kind of documentation for the QGIS Python API that actually works/gives the correct information. It is obvious that there is no actual code ...
1
vote
2answers
322 views

QGIS raster calculator using abs() function

Is it possible to use the Abs() function in the raster calculator in QGIS? I've tried it, but it didn't work.
1
vote
1answer
244 views

Cannot produce pie chart in QGIS 2.2

I have a shapefile to which I joined two tables from a MySql database. I used one column of the first table to color the polygons in my shapefile which works fine. Three columns out of the second ...
1
vote
1answer
573 views

How to convert float to raster in QGIS

I have downloaded bathymetric data into QGIS. In order to use it I need to conduct a float to raster conversion. I have not been able to find how to do this on any of the forums. I have unsuccessfully ...
1
vote
0answers
190 views

QGIS processing framework SAGA NaturalNeighbor in external Python Script - No Output

I want to build a little script, which generates a NaturalNeighbor grid based on a point Shapefile. The script runs within my PyDev environment without any error messages, but no outputfile is created....
0
votes
0answers
54 views

GDAL_Translate not compressing when NoData value is set

I am trying to compress a .TIF file using GDAL_Translate or GDAL_Warp. My Raster is 32mb to start with. When I use GDAL_Translate with the COMPRESS=PACKBITS option, it compresses to 1.9mb. However ...