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

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Calculating distances across land only

I am trying to do point to point distances in QGIS but I have points to point distances that are being calculated across oceans. Given people don't generally fly around cities does anyone know a way ...
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6 views

unsupervised classification in qgis (Orfeo toolbox)

I want to run an unsupervised classification of two landsat images in qgis. Therefor I want to compute a kMeans and a SOM (self organizing maps classification). Unfortunately it doesnt work. I tried ...
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9 views

How to calculate the 3D length of line segment in QGIS?

I've been looking through all of the GRASS commands in the QGIS 2.10 processing toolbox and it seems like one of these must be able to do this but I haven't found one yet. There is 'v.sample' which ...
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0answers
15 views

How do you merge overlapping .asc files in QGIS with topography and bathymetry?

Firstly, apologies for any incorrect terminology - this is my first time trying to manipulate GIS data. I have two files. The first is higher resolution (SRTM) topography data for a region of islands ...
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12 views

Gravity/Huff model tools in QGIS without rasterlang plugin?

As the person of this question: Gravity/Huff model tools I am looking for a tool to simulate a gravity model using a point-based layer. As in the case there, my points have a z-value and the higher ...
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1answer
17 views

Checking if a POI is on the road

I have a list of POIs from around the world and their latlongs. I also have the database from all roads in the world. What I want to do is find the popular roads from all of these. My idea was to ...
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14 views

Need to edit info to new column for label and concatenate information which is alphanumeric

I need to end up with the following: Jones, H.L. A-345 The data is entered into Survey Name (as string). Survey Abstract #is entered as "345" I need to add "A-" to the number, and then concatenate ...
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1answer
24 views

How to change the border style of a symbol

In my maps I have a symbol, his type is polygon, I want to change the line style of the border, actually is solid , I had to put it in dash Is there a simple way to change it ? i think to the ...
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21 views

How to edit a shape which the toggle Edit buttom is noot enable in QGIS?

I just download a shape file (polyline) from internet and I would like to do some modification in the line, but the Toggle Editing buttom is not enable. It seems that the file is locked and is not ...
2
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1answer
32 views

How to find if map layer registry is empty?

In my script I want to open layer named my_layer if it is in the map layer registry. I use following code for it: inputLayer = QgsMapLayerRegistry.instance().mapLayersByName("my_layer")[0] If not ...
2
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0answers
20 views

PyQgis: How to access a deleted features attributes (before committing)

I have a signal setup for a feature deletion event on a layer: self.layer.featureDeleted.connect(self.feature_deleted) When I try and grab an attribute from the deleted feature on the slot, a ...
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0answers
13 views

How to scale SVG symbols which are not label background on zoom level in QGIS

I need to scale the SVG symbols on zoom level. @Underdarks answer in the posted question did not help me thus I can't set the SVG symbols as label background for I have labels which should not be ...
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1answer
33 views

Polygons in one layer have different attributes

Is it possible in PyQGIS to have in one layer more polygons and some would have one set of attributes and another different? E.g. Polygon_1(name, size, average_age), Polygon_2(name, size, ...
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3answers
244 views

Free printable background map: land use, rivers, etc

I am looking for a free printable background map of europe which should look more or less like the OCM landscape: land use, major rivers, coast lines Is there any WMS or raster set whiche enables me ...
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1answer
23 views

How can I create a QGIS plugin that needs an external Python library?

I’m trying to enhance QGIS's Profiletool plugin by adding DXF export functionnality. For this, I need to to import dxfwrite library. As it's installed on my computer, i added the following lines to ...
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0answers
11 views

Normalized icon for BOYLAT

I try to find normalized icons to use for the BOYLAT ( lateral buoy ) I find description, but for the boylat it seems that different shape to show different buoy link for the description ...
1
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1answer
12 views

Rendering of SVG for layer symbols using QGIS?

I have a little problem with the rendering of SVG for layer symbol. I want to creeate a categorized symbol to show different style of buoy I have for that two icons the first is an half circle ...
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0answers
21 views

Why do pixel (cell) values change for 32 real NDVI values when taking from Multispec to QGIS?

Landsat 5 values change from normal NDVI -1 to 1 when created in Multispec as a 32 bit signed data image. When adding the raster layer in QGIS, the value range changed to 0-255. How does one ...
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1answer
15 views

Opening MapInfo .TAB file containing text objects in QGIS?

Whenever I try to open a MapInfo .TAB file that contains text objects in QGIS, the text objects are converted to point objects. Any help, please?
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1answer
30 views

How to get PostGIS DB name from QGIS layer?

I'm writing a custom Processing script that needs to know which database connection a vector layer resides in. I can't find anywhere in the API a function to return this information from a layer. So I ...
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3answers
49 views

Grass toolbar for QGIS 2.10

I don't see the GRASS toolbar in QGIS 2.10 (Pisa). There are still GRASS commands in the Processing toolbox. I know there was some upgrade of GRASS for 2.10. Is the toolbar not available anymore? If ...
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1answer
44 views

Loading Natural Earth *.prj file into QGIS 2.10.1?

I have found solutions for this problem in other versions of QGIS, but none that apply to the newest version 2.10.1. Whenever I try to import a Natural Earth Raster projection that is a prj file I get ...
2
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0answers
32 views

How to load a style from POSTGIS in PyQt

The thing is that I have four styles I have created in QGIS through the GUI and saved into a postgresql database. I can see them in the table named layer_styles I have seen similar questions asking ...
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2answers
22 views

How to put a frame around a legend using QgsComposerLegend?

I can already see this being a simple answer but I'm stumped with this. I want to create a frame around a legend created by a PyQGIS script Code snippet is: legend = QgsComposerLegend(c) ...
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1answer
24 views

How can I check in QGIS python if an atrribute is included in my layer?

I use the following code: for field in self.layer.pendingFields(): if field.name()=='elevation': do this else: do that Although there is an elevation attribute in my layer ...
2
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1answer
33 views

what is the “clip” feature for color ramps?

In the singleband pseudocolor band rendering, there is a boolean checkbox "clip". What does this do? I don't notice a difference in my maps and haven't found documentation for it. Thanks
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46 views

Unable to stylize as pseudocolor render type

In a raster layer's Style Properties, I can choose pseudocolor render type, and choose a color ramp and classify the raster. However, when I click the 'Apply' button, or click 'OK', the ...
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1answer
19 views

Updating a column in MapInfo based on Symbology or colour

I am transferring a large dataset from MapInfo (V 12.0.2) to QGIS (V2.8.1) and I want to be able to create a column in the MapInfo attribute table that differentiates features with different ...
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0answers
17 views

Problem using EPSG:3395

in my application I use OGC:CRS83 for the coordinatereferencesystem, but now I had to change it to EPSG:3395 when I call : mQgsCoordinate->createFromOgcWmsCrs("EPSG:3395") there is nothing in ...
2
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0answers
49 views

Create Indexes Within a View? How could I Speed up Spatial Queries Over a View?

I´m trying to add a view from postgis using QGIS, what´s facile. The problem is that it´s taking too long to load it and to perform any kind of operation, for example, as simple as counting rows. It´s ...
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0answers
10 views

Unable to make qgis build in cmake

I am trying to build qgis without any change in source code which i have downloaded from github using clone and i have download OSGEO4W from qgis.org and the same is installed in c drive. I have ...
2
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1answer
25 views

QGIS: Finding electric network loops

With QGIS, how can we analyse an electrical network to find loops? Using Python is not a problem, however there is not a solution in the QGIS Python API. The QgsGraphAnalyzer has dijkstra and ...
2
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2answers
29 views

QuickOSM returns no result

I am trying to download the polygons for the Umweltzone Heidelberg from OpenStreetMap using QuickOSM in QGIS. I queried by name as shown in the screenshot: The corresponding OSM script looks like ...
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0answers
19 views

Error in Editing Point Shapefile: I can't add a new point feature

I want to add a point to a point shapefile. I place the cursor in an empty field. The strange thing is that the point of the point shapefile that is nearest to the cursor is highlighted. If I click ...
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4answers
238 views

Is there a quick way to clear all attributes from a layer but leave the polygons in place?

I have a layer with several polygons, each of which has data in over 100 fields. I need to create a new layer with all the same polygons, but with all their data fields blank (set to 0, Null or empty ...
2
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0answers
29 views

How to rename field names in a shapefile attribute table without table manager using python

By using the table manager we can rename the field names but i want to rename of fields using python. How can i do that?
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0answers
14 views

how to make rectangle selection by mouse on my map(world shape file) in qgis in python

I want to make a rectangle selection using the mouse on my map (world shape file) in qgis in python and extract the lat lon of the selection area but I don't understand how to do it. I don't have any ...
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1answer
22 views

QGIS Print composer dynamic labels

I have created an Atlas. One of my layer contain height restriction for bridges. I wish to create a label that show the lowest height restriction. I need to get the height values from my table that ...
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2answers
194 views

Boundary from Points

I have a point cloud and need to process a very detailed boundary around the outer points. Is there a tool in QGIS? Convex hull is not detailed enough. Thank you!
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1answer
15 views

How to read non-spatial data using PyQgis?

I'm generating maps with QGis. What I do is generate a bunch of non-spatial data on a set of cities (using VBA), and still using VBA, generate a python code that will automaticaly output general map ...
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1answer
22 views

What is the meaning of DN and DRVAL2 categorie?

I try to find the meaning of the categories DN and DRVAL2 when I used them in the command: lrenderer = new QgsCategorizedSymbolRendererV2("DRVAL2" , Categrories ); Is there any tutorial or ...
2
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1answer
26 views

How to break a closed line when intersect with polygon

I have a number of polygons (in lines shape) which represent the new condition of an area and a numder of polygons (in polygon shape) which represent the old condition of the same area. How can I ...
2
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1answer
15 views

Inserting image in an attribute table in QGIS Composer?

I'm trying to create second page of map atlas. In this page I need to show all records in the range of current atlas page. I've used Insert Attribute Table tool in composer and it worked. But I need ...
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1answer
17 views

GPS points of a vehicle snapped to a specific polyline path [duplicate]

So I have been capturing bus GPS locations for a while now, and I am became interested in snapping them to their corresponding polyline (route). While at first this seemed like an easy enough task I ...
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0answers
14 views

Has there been any further development in the integration of QGIS plugins to Processing Modeler? [duplicate]

I have read that there is no ability to use QGIS (2.8) plugins when building a model in Processing Modeler. All of these posts were a few years old so I was curious if there was any development or ...
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1answer
18 views

How to Convert Just a Sulawesi Map to Leaflet

I'm still develop a Web GIS that show population distribution in form of heat map. I'm use Quantum GIS with Open Street Map & Q2Leaflet Plugin as a tool to accomplish it. The problem is, I just ...
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0answers
40 views

Repeated GPS coordinates in data are creating stacked points on map in QGIS

I have 30+ events of data collection for each GPS location (previous person on project has simply added new rows for each data collection period). When I import the excel file (via CSV format), each ...
2
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1answer
30 views

Why does Points2One complain “Can't make a polyline out of one points.”?

I know this question has been asked before .I am trying to connect pairs of points by lines using the Points2One tool in QGIS. I have created the data and exported it as shape file. The data looks ...
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1answer
36 views

Is setting raster CRS in QGIS georeferencer useless? Still have to choose the same for target SRS?

I'm trying to move out of ArcGIS into QGIS permanently for basic operations, so be patient please. Here is the problem. I'm trying to georeference a topo map in EPSG:22523 (Corrego Alegre UTM). I did ...
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0answers
9 views

Problem on rendering categorizedSymbolRendererV2

Finally my code works but the renderering display just one color instead of 4 I don't know why, I follow the sample code of the snorf.net website and the sample code in the qgis python programming ...