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

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How to Make an Outside Buffer in QGIS?

I have a layer of street segments that are within a given distance of a fire station. Now I want to make a border around these street segments. If I use Buffer, it puts a buffer around each segment. ...
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0answers
27 views

Discover multipart features in a layer in QGIS

I am trying to identify multipart features using QGIS version is 1.8.0. I've tried: look at the attributes table select a random feature and check in the canvas if there are multiple geometries ...
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0answers
12 views

QGIS 2.4.0 doesn't support multiple types of geometry in GML file

I'm testing GML 3.2.1 data according to INSPIRE Data specification (version 3.0). Data for theme Cadastral Parcels shall have both polygon geometry and definition point. When I download data from my ...
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1answer
30 views

QGIS - Identify overlapping polygons in single layer

I have a shapefile of buffered points in QGIS. I need to display all buffer polygons in this layer which overlap. I have experimented with the intersect tool, but this only seems to work if I am ...
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4answers
225 views

What are good colour schemes for large density flow maps?

I came across nice QGIS tutorial for mapping flows. In contrast to Alasdair, I have zero talent in colour choice. Can anybody recommend some good starting points for nice colour schemes (I'd be ...
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1answer
11 views

Geoprocessing tool Difference from the Terminal?

I have used QGIS Geoprocessing tool Difference to cut polylines (SHP) into to smaller pieces using a polygon (SHP). This works very good in QGIS. Now, to speed up the process, I'd like to be able to ...
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1answer
19 views

QGIS 2.4: How to get Atlas to print all features not just the one visible in preview

I have a number of "zones" described by polygons that I use to produce a set of larger scale maps that I used to export into a pdf. This has stopped working (when I moved to 2.4 ??) and now I ...
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0answers
6 views

Error: Cutline feature without a geometry. > Raster Type

I've got an "Error: Cutline feature without a geometry" on QGIS 2.4.0 Chugiak. I have 2 samples (A raster type and a vector type), they have the same coordinates (EPSG:4253 - Luzon 1911) Then I tried ...
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1answer
49 views

Ideal file format for QGIS that allows mixed geometry types?

I have a spreadsheet for an archaeological project that is hosted on Google docs. This allows multiple contributors to edit and update the table as revisions and field data comes in. The table is not ...
2
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1answer
33 views

How can I properly clip a shape file to get the section I want using QGIS?

I've tried the other "how to clip" instructions here, but consistently get an empty shapefile from the clip. QGIS Version: 2.4.0-Chugiak OS: MacOS 10.10 Input File: San Diego (South Map) 1999 Topo ...
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2answers
43 views

NDVI derived from Landsat band 3 and band 4 using QGIS raster calculator shows the different range when opening in the ArcGIS

I have calculated Normalized difference vegetation indices from landsat 5 band 3 and band 4 that have 0-0.38 minimum and maximum ranges respectively. But whenever I open the same NDVI.tiff file in ...
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32 views

Iterating between two layers using QGIS python

I will try and explain my situation as clearly as possible. I just created my first plugin that is being used to analyze between various layers and give back quantities to the user. Most of it is ...
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1answer
22 views

Another Way to Join a New Column to a DBF if OpenOffice is Giving a “Longer Than the Number of Digits Allowed” Error?

When I need to add a data column to a DBF, I always download the shapefile, open the DBF with OpenOffice for Mac, us a VLOOKUP( ) to add my data to a new column, re-save the file as a DBF, then open ...
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0answers
25 views

Does QGIS work with Anaconda?

I am trying to get QGIS to work with the Anaconda distribution of Python but I do not know how to get this to work. In one of the answers it was mentioned that QGIS does not work with Anaconda and I ...
2
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0answers
30 views

How complete are the Fusion tools in QGIS?

How complete are the Fusion tools in QGIS? I have them installed and (vaguely) working, but there are only about ten of them. Is the idea of having just a few tools available, that one can use ...
2
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1answer
25 views

How to find length of a discontinued line feature

I wanted to find the length of features in a road layer. So I go through each feature in the layer and used, line = feature.geometry().asPolyline() to find the points which particular feature is ...
2
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1answer
32 views

How to use qgis coordinate transformation in user code

I am now working with coordinate transformations between different CRSs, e.g. latlong to UTM. After comparisons, I found out that the coordinate capture plugin in QGIS is quite accurate for the ...
2
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1answer
28 views

QGIS freezes after making and saving many edits to a layer

I work with QGIS 2.4 on windows 7. The problem occurs when I work on a layer and save it many times. After a random number of saves, pressing the save button once more causes QGIS to freeze, all ...
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0answers
32 views

QGIS assign multiple points data to closest polygon

I've got two layers: point layer polygon layer I need to add the points attributes to the polygon by location (if the point is on top of polygon add the atribute as a new field. I thought of ...
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1answer
47 views

How to use pre-generated Tiles

i have just created Tiles with Qtiles on Qgis, but how can put these folders (tile .png) on Geoserver or Mapserver? is it possible? I am trying to put the folder in C:\Program Files (x86)\GeoServer ...
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2answers
32 views

QGIS Heatmap plugin how to convert resulting raster values to meaningful values for legend

I am using QGIS and heatmap plugin and I need help with finding the meaning of the resulting raster values. I know there have been some questions, but none of them helped. This is my point layer input ...
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0answers
26 views

Spatial join with snapping

is there a tool in QGIS which is able to perform a spatial join with the possibility of define a snapping radius? For better understanding: I have 2 point shapes with attributes I need to join by ...
2
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0answers
23 views

What Does the Cell Value in a Composite Raster Mean?

When I make a composite raster in QGIS using the GRASS r.composite tool and then click on a certain cell I get these values in the blue/green/red/composite rasters: blue = 124 green = 124 red = 172 ...
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0answers
27 views

How can I find the center of the circle or ellipse I just created

I need to draw circles and ellipses with a certain length/width/ radius. I used the rectangles ovals digitizing plugin to create them, but only measured roughly the circles' radiuses. It would be ...
3
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2answers
71 views

Correctly merging DEM rasters and eliminating edge effects

I'm using 10m DEM rasters from the NRCS Data Gateway for a large portion of California. The problem is some strange tiling that appears after merging, but isn't present in the original data (before ...
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0answers
23 views

Can't find GPS in QGIS for Android

I have installed QGIS on my samsung galaxy note 10.1 (not 2014 edition) but I can't get contact with the GPS. I have the GPS information tool, but when I try to connect, QGIS shut down or nothing ...
2
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2answers
128 views

QGIS on Mac OS X 10.10 Yosemite

I just upgraded to OS X Yosemite therefore I have to use Java 8 (at least this is what Java tells me). After installing QGIS I was trying to start QGIS but I got the error message that I have to have ...
2
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2answers
35 views

Setting layer visibility in QGIS Python API

Im having a problem toggling the visibility of map layers in pyqgis (2.4). I have a simple interface, just the map canvas, no legend, and basically a radio button that toggles between two raster ...
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0answers
12 views

How to move to next feature by pressing right click

I have written the python code for adding vector layers,for getting and selection of features,for zooming. But my doubt is how can we write a python program where pressing the right click of mouse ...
0
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1answer
15 views

Enable ecw QGIS 2.4 on Linux Mint 16

I upgraded to Mint 16 and QGIS 2.4 and unable to get ecw to work following various guides available. Anyone willing to explain how to and why it is so hard. I run it on a windows machine out of the ...
1
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1answer
14 views

Interpolate dxf polyline vertex elevation from DTM?

I am working on several autocad polylines (with several vertices...) that have the exact N,E coords but now I would like to add the elevation data for every polyline's vertices from a dtm. I thought ...
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1answer
51 views

How to extract and save using QGIS?

I am new to QGIS and just downloaded QGIS 2.4 Chugiak. I am practicing QGIS by using training manual, as mentioned in above subject. I have questions in regard with the sentences in page 7: You ...
2
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2answers
32 views

Get cell size for raster in QGIS

How do you get the cell size of a raster in QGIS? This is a simple matter in Arc, just look at the properties. QGIS has properties, but no raster cell size. Thanks.
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1answer
23 views

Export background tile map to raster file

In QGIS I managed to display the ship traffic density from marinetraffic.com as a background tile map using the TileLayer plugin. Here is my TileLayer.tsv file: #title credit serviceUrl yOriginTop ...
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0answers
46 views

Generating Canal on DEM using ArcGIS for Desktop?

I want to generate a canal going from point A to B with a given slope. The canal should be on the underlying DEM. Is there any way to do this with the tools in ArcGIS 10 or do I have to do it ...
3
votes
2answers
52 views

Identify all continuous networks in a dataset

I have a set of pedestrian streets for a city. I would like to assign all of the streets that can be reached to one another along a continuous network to a unique group. I am wondering if there’s an ...
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0answers
22 views

Querying related tables in QGIS

I have a parcel layer and a table of property sales. I have the two tables related (it is a one-to-many relationship) in a QGIS project so that when you click on a parcel you see all the related ...
2
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1answer
35 views

QGIS syntax raster calculator

I'm working with QGIS and I want to reclassify a raster in different ranges. Using the following statement does not work even recognized as valid (2950 <= "dem_tallat @ 1"> = 3050) = 3000 ...
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0answers
29 views

Exported QGIS composer map using Openlayers base map has city labels shrunken

I've created a map in QGIS composer and I'm using the Google physical base map via the openlayers plugin. When working with the map in QGIS canvas & the composer view, I see city names with ...
1
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2answers
71 views

How to draw a polygon given a distance and bearing in QGIS

Apologies if this question has been asked before I'm not come across it. I want to draw a polygon given a length and a bearing, basically a square with lenght 1m. I cant seem to manage it with the ...
0
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1answer
38 views

Using QGIS and PostGIS for multi-user capabilities, similar to ArcSDE for ArcGIS [duplicate]

I have previously used ArcSDE technology with Microsoft SQL Server to allow for multi-user database editing. My ESRI licenses have recently ran out and I have been using QGIS for my GIS work. I am ...
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0answers
35 views

Guidelines for publishing large datasets on QGIS Web Client

Can anybody provide simple guidance to publishing large datasets on QGIS web client? I have a mixture of shapefiles and rasters to display. Biggest shapefile is 230 MB. Biggest raster is 1.4GB. At ...
3
votes
1answer
64 views

How to remove abnormalities from the Green vegetation fraction

Study area was clipped by using the shape file from Band 3 and Band 4. First, Band 3 and Band 4 were converted to at-satellite brightness temperature by using the built-in function in semi-automated ...
2
votes
2answers
41 views

QGIS 2.4.0 marker line interval does not work properly when line is bending

I am trying to style a line using marker line option. When I am using styling the line in the style window everything looks nice as you can see on the print screen bellow. I am using three line ...
3
votes
2answers
80 views

QGIS Installation on Windows

I'm newbie to QGIS and to this forum. I want to develop application using Qt on QGIS to real time updation/mapping of a symbol using GPS co-ordinates. Initially i have installed QGIS on Windows 32 ...
0
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1answer
21 views

osm2pgsql doesn't run in a QGis plugin

I have a problem with osm2pgsql when it runs in a qgis plugin. The function i use looks like this: osm2pgsql = "osm2pgsql -s -d {databaseName} -U {databaseUser} -H {databaseHost} -E ...
3
votes
1answer
40 views

matching shape file to csv within QGIS - all strings

I am trying to link a csv to a shape file using the method as described in this tutorial: http://maps.cga.harvard.edu/qgis/wkshop/join_csv.php It seems to work fine but the problem is that the csv ...
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0answers
17 views

Exporting QGIS Raster/Vector layers into one PDF? [duplicate]

I have seen a similiar post to this a while back (Is it possible to export GeoPDF from QGIS?), and thought I would try asking it again to see if there has been any improvement or new knowledge on ...
3
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3answers
89 views

Visualize overlapping line vertices in QGIS

I am trying to inspect the vertices of some linestrings in QGIS 2.4. My goal is to visualize every vertex of a line and easily find those that are duplicated. To clarify this, for an example line ...
3
votes
1answer
79 views

How do I merge DEM rasters correctly?

I've been struggling with this problem for awhile. Here is a curvature raster to illustrate the problem. I'm using 10m DEM rasters from the NRCS Data Gateway for a large portion of California. The ...