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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1answer
70 views

How to get the signal when the color changes in pyQGIS?

I would like to have the signal when the color of a vector layer is changed by the user. In the doc, there is a signal that seems to fit ...
1
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1answer
17 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 ...
0
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0answers
9 views

Prevent Overlapping Features in QGIS from Being Faded

I have multiple layers in QGIS that I've set as transparent so I can see their respective features. However, I would like one layer (showing proportionally sized points) to NOT fade when it overlaps ...
6
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0answers
177 views
+50

How can I create a form so the user has to be authenticated to access a project?

I have a login form in QGIS and when it is loaded, python gives me an error for, apparently, not recognizing the findchild part. This is due to the fact that the form isn't loaded before the script is ...
5
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0answers
219 views

How to create a chart of elevation using points?

I am using shapefiles with basic information including the x-, y- and z-coordinates. I want to see how the objects (in this case points, which are finds from an excavation) are scattered along the ...
1
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2answers
47 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, ...
0
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1answer
15 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 ...
0
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0answers
10 views

How can I extract the latitude and longitude from a s57 File [duplicate]

I had to extract the longitude and latitude from a s57 file, in order to superpose a satelite view from the same point. These coordinate will allow me to get the exact position on google map by ...
1
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1answer
24 views

How can I import shapefile in python?

How can I import a shapefile in python? from PyQt4.QtCore import QSettings, QTranslator, qVersion, QCoreApplication from PyQt4.QtGui import QAction, QIcon, QFileDialog # Initialize Qt resources from ...
2
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0answers
27 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 ...
3
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0answers
33 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 ...
70
votes
4answers
46k views

File Geodatabase (*.gdb) support in QGIS?

Following questions: Open Source Tool capable of reading Esri File Geodatabase (.gdb)? How to access file geodatabase in Qgis? How to get FGDB support in GDAL 1.9 without compiling? I have spent ...
6
votes
6answers
252 views

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

I have a Shapefile layer in QGIS 2.6 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 ...
3
votes
2answers
41 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 ...
1
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0answers
13 views

What solutions to use QGIS as insert tool for a Postgres relationnal database?

I have a Postgres/PostGIS relational database and I would like to use QGIS as an interface for inserting data. The thing is that my database is quite complex and I need my tool to handle the following ...
0
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0answers
11 views

QGIS measure growth in special directions

I want to measure the growth of different areas in special directions. The same as in this article of M.S.Moeller on page 5 (Figure 5 and 6). But I don't know how to build such a Wind Rose in Qgis. Do ...
2
votes
1answer
26 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 ...
1
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1answer
12 views

automated selection by attributes and location within another Layer

I have two Polygon Layers. Layer A are Districts of a City and Layer B are Blocks of a City. Currently i'm working with QGIS 2.6.1 and i don't have access to any other GIS. What i'm trying to do is: ...
4
votes
2answers
79 views

How to run qgis scripts in parallel across remote server(s)

I have a stand alone python script using qgis that I wrote with the help of the SE question here The script takes three arguments being; an input file path, an output file path, and another input ...
1
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2answers
227 views

How to create a polygon feature using Python?

I'm making a plugin for Quantum GIS in python. I have a polygon layer and want to create a new feature. So far, I have this because I need a polygon geometry to add the feature: surface = ...
1
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2answers
83 views

Why is SAGA from the Processing Plugin not recognised?

Similar to this post: SAGA algorithms don't work in QGIS 2.8 except the fact that SAGA does not appear at all in the Processing Toolbox: As a check, I used the Python Console with the following ...
2
votes
3answers
580 views

Draw line between points from multiple datasets

I have 2 point datasets and want a tool or script to draw a line between all points in one dataset to all the points in the 2nd dataset. Is it possible? I have tried ESRI "Point Distance" and ...
2
votes
3answers
2k views

Convert Shapefiles to GeoJSON?

I'm trying to convert Shapefiles from the State of Texas Senate Districts website into a GeoJSON file for use with Google Maps API. I'm using QGIS to facilitate but I can't get the ...
0
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0answers
20 views

Merge layers (SAGA) ERROR

with QGIS 2.10 it is not possible to merge vector layers with the "Processing-Saga" tool (merge layers). The following error log comes up: Algorithmus Merge layers startet... shapes_tools "Merge ...
1
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1answer
293 views

How to generate random points with minimum distances between points in multiple polygons

I am looking to create random points for a random stratified survey. There are three different categories being surveyed; for each, I have a single shapefile, each containing a number of polygons. I ...
2
votes
1answer
21 views

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 ...
1
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0answers
25 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 ...
0
votes
3answers
5k views

Why won't QGIS recognize my GPS?

Garmin BaseCamp recognizes and receives data from my GPSmap 60CSx, but QGIS GPS Tools plugin does not. Am I missing a step? I want to be able to transfer data both directions. MacOS 10.6.8 QGIS ...
3
votes
1answer
257 views

How to compute average slope and area-weighted average slope?

I am learning GIS for use in hydrologic analysis. Related to computation of overland flow there are two types of slope that I would like to be able to obtain from GIS. The first is average slope for ...
4
votes
1answer
37 views

How do I count the number of vector lines that pass though a given raster cell?

I am working on a project (currently in GRASS7 though I'm not against exporting to Arc or R or other software if necessary) where I am generating thousands of shortest cost paths (using the r.walk and ...
1
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0answers
55 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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0answers
10 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 ...
6
votes
1answer
185 views

How to create an Atlas based on point attributes?

Essentially I am wanting to produce an atlas based on a categorical field in a point layer. i.e. I have a point layer of childcare providers with the categorical field "Provision". I've categorized ...
1
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0answers
24 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 ...
1
vote
2answers
132 views

System variable PATH overwritten in Qgis

The system env variable 'PATH' seems to be overwritten in Qgis, replacing it with their own values. Not sure if it was intended or not. Anyway in version 2.2, I could solve it by go into settings and ...
1
vote
1answer
23 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 ...
0
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2answers
745 views

How can I download maps from mapquest?

I need to get a detailed map for my own purposes. I need it detailed as much as I can see the buildings (like google map hybrid mode). I went to http://open.mapquest.com/ but I couldn't find the way ...
2
votes
0answers
33 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 ...
1
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0answers
15 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 ...
15
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2answers
9k views

How to rename attributes/fields in a shapefile attribute table?

I would like to rename some fields in my attribute table: Like rename XRF_N3in something else. It seems quite a easy issue but I don't find any information about how can I do that... I've QGIS 1.8 ...
1
vote
3answers
56 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 ...
0
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0answers
22 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
votes
1answer
34 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 ...
3
votes
1answer
927 views

QGIS python - reference a layer in the table of contents

I'm trying to create a plugin for QGIS using python, But need some help. I want to 1.Zoom to a layer and 2. make the layer visible(switch off or on). But I have managed to zoom to an active layer by ...
2
votes
2answers
31 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 ...
0
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0answers
21 views

Fail in searches on the joined table data

When a table is joined to a standalone table, the searches on the joined table data return a fail. Is there another way to solve this inconvenient without save the layer with joined table under a new ...
3
votes
0answers
303 views

Create a path following a road, interpolating from a set of points

I have several hundred vehicular routes within a city from which I wish to create shapefiles. These take the form of directions such as "From Green Street, turn left into Brown Street, Right into ...
1
vote
1answer
20 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 ...
2
votes
1answer
284 views

How to deal with clipper error “cannot compute bounding box of cutline”?

I have merged about 20 OS tiles in to a single raster and I am trying to clip the merged tiles using a single polygon which itself was created from a small number of ward boundaries, merged using the ...
1
vote
3answers
253 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 ...