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

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10 views

How to divide attribute table in map composer - QGIS 2.4

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

Per-pixel (statistical) calculations on a raster stack using GDAL

In R, it's relatively trivial to perform per pixel calculations based on a raster stack (e.g., get std.dev for each pixel on a 12 layer GeoTIFF). Unfortunately, the speed is less than desirable when ...
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0answers
4 views

How to get a GML overlay on Google Maps?

Anyone know how to get a GML file to show as an overlay on Google Maps? To be honest I don't know my GML from my KML, or my ETRS89 from my WGS84, as this topic is completely new to me. A bit of ...
1
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1answer
7 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 ...
2
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1answer
160 views

How to make labels' size relative to the map in QGIS1.8?

I want to make my labels' size changed automatically with the scale of the map,so in the menu of "Layer labeling settings",I set the Text size" in map Unit".However,the labels in the selected layer ...
1
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1answer
111 views

Running model in QGIS gives ERROR: Missing mandatory parameter?

I am trying to make a batch model to convert band 2 and band 1 MODIS 8 day composites into NDVI. The input files are in tif format, but I want the output to be saved in Idrisi .rst format. I am ...
2
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2answers
107 views

How to draw a square from 2 coordinates?

I have a CSV file with the following output id, x min, y min, x max, y max, value 1 , 0 , 0 , 100 , 100 , 5 2 , 0, , 100 , 100 , 200 , 10 3 , 100 , 100 , 200 , 200 , 15 4 , 100 , 0 ...
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1answer
11 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 ...
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1answer
30 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
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1answer
26 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
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3answers
44 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
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1answer
38 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 ...
1
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1answer
38 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 ...
0
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1answer
33 views

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

Hint: 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?
0
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1answer
376 views

Calculate area covered by a particular raster layer within polygons in QGIS

I am trying to extract information on vegetation cover within a set radius of point locations (my sites). I have succeeded in creating a new vector layer of circles with a 5 km radius around my sites. ...
1
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2answers
36 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 ...
0
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0answers
147 views

Vector layer and google map do not line up in PDF

I'm using qgis 1.8 with windows 7. When I use print composer to export as PDF, the google map does not line up with the vector layers. Please help.
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0answers
17 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?
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2answers
497 views

How to draw a Circle of fixed radius in QGIS using QgsMapCanvasItem?

I have derived a class from QgsMapCanvasItem for drawing circle of some radius at a given latitude and longitude. In my paint function I am using QPainter to draw the circle as void paint (QPainter* ...
4
votes
1answer
63 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 ...
1
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1answer
27 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
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1answer
252 views

Can I prevent QGIS raster clipper from changing output cell/pixel size?

I have performed a DEM extraction using the clipper tool in QGIS 1.9.0 Master, using a mask layer, the original resolution of the DEM is 20x20 but in the resultant DEM the new resolution is ...
1
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1answer
16 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 ...
1
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1answer
223 views

Why doesn't the Kernel Density Estimate function appear in AniMove plugin?

can anyone tell me why the Kernel Density Estimate function does not appear under my AniMove plugin in QGIS? I can only perform the MCP. I run Windows OS.
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1answer
23 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 = ...
2
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1answer
27 views

Loading features attributes into 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. ...
1
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1answer
521 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 ...
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0answers
22 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 ...
1
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1answer
174 views

How can I map data points to OpenStreetMap (OSM) line data?

my goal is to filter measuring points of vehicles by mapping them to streets. So I could filter out all the false data located in fields and rivers and so on. I imported my data into a PostGIS ...
0
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2answers
100 views

Adding Oracle Spatial View as Layer in QGIS?

Is it possible to add an Oracle Spatial View on QGIS MAP? My view is registered on MDSYS metadata but, when I connect with Oracle DB, it is disabled on the list. QGIS Desktop 2.2.0 Oracle Database ...
1
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1answer
29 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 ...
3
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1answer
263 views

Saving selection as new layer in QGIS 2.4?

I've selected a number of polygons from one layer and want to create a new layer. Because I can't right click using a mac how do I find "Save Selection As". Its not in the list in the "Layer" ...
0
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1answer
369 views

Reverse geocoding polygon co-ordinates?

I have a large dataset of polygons for property sections that I need to reverse geocode. It was recommended that I use a GIS like Quantam to do this however from my research I am not 100% sure if a ...
3
votes
1answer
104 views

Calculate population coverage?

I am relatively new to QGIS and hope I explain this right. I am looking at the percentage of an population that has geographical access to healthcare. Therefore I have one shapefile with village ...
0
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1answer
23 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 = ...
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0answers
12 views

How can one use Google Maps API to mimic QGIS projection/CRS

I used QGIS to find the extents of a list of features. However, the resulting data auto-generates the CRS and changes it from WSG84 to a custom one. Is there a way to use the autogenerated CRS in ...
1
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1answer
10 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 ...
6
votes
1answer
72 views
+50

How to combine raster and attribute table in QGIS?

I have some rasters representing string categorical variables. Each raster contains integers, used to translate the categorical variables. I have also the .csv tables giving the meanings of the ...
0
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1answer
49 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 ...
1
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0answers
26 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
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1answer
33 views

CRS of QGIS bounding boxes

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 ...
2
votes
1answer
39 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 ...
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0answers
25 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?
1
vote
1answer
84 views

Default workspace in QGIS 2.0

I have been using QGIS for quite some time. It always happens that I change the position of toolbars and panels to make the workflow more efficient. But then when I close QGIS and I have to start a ...
0
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0answers
33 views

QGIS 2.4 How do I find and change measurement units? [duplicate]

I want to create 1,000m buffer around an object, but when I enter 1,000 as the distance I get something that looks more like a 100,000m buffer. I can enter 0.01 to get what looks like a 1,000m ...
4
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3answers
154 views

LiDAR data density, returns per square meter

How can I compute a raster showing the number of return points per square meter using SAGA GIS or other open source software? My goal is to obtain a mask which would show me the places (cells) ...
2
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2answers
86 views

Exporting 16 bit single-band to 8 bit in SAGA/QGIS

Everytime with every function (e.g convert data storage type or gdal-translat -ot Byte) the output is a completely white map with a black border. only the "save as" export works, but the TIFF also ...
2
votes
2answers
82 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 ...
6
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2answers
6k views

How to calculate polygon areas and perimeters using QGIS?

Using QGIS, if I load a polygon layer and make a new column, how do I fill that column with the: area of each polygon and another column with length of the perimeter of each polygon?
5
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1answer
119 views

fTools “Join Attributes by Location” missing in SEXTANTE/Processing Toolbox

I am working with the new Processing Framework in QGIS 2.0.1. I really like the graphical modeler, because it allows my to make my own tools without having to be able to write pyhton or any other ...