Tagged Questions

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
49 views

How to load a *.qgs file in a C++ QGIS standalone app?

I'm using QGIS-2.4.0 API to develop a standalone app by C++. I saved a test.qgs file in QGIS Desktop software, in the project, there was one layer and it was visible. Then I loaded the test.qgs ...
1
vote
1answer
43 views

Repetitive behavior in QGIS plugin in connection between Cancel button and pushButton

I'm trying to build a QGIS plugin where I need to ask for a file name using a pushButton connected with a QFileDialog object. I've built a simple plugin using the QGIS plugin builder (putting the text ...
1
vote
2answers
28 views

QGIS 2.4 crashes when symbolizing QgsComposerShape in Python with ScriptRunner

I'm attempting to use ScriptRunner to output a jpeg of a red rectangle using QGIS Composer to understand the QgsComposerShape. Everything works except QGIS crashes when the symbol is applied. The ...
4
votes
1answer
63 views

Is there a public repository of common formating styles for QGIS? Specifically for Tiger data?

I have downloaded the Tiger data for a map I'm working on and wonder if there is somewhere I can download the common formatting styles for these shapes so I don't have to reinvent the wheel. For ...
1
vote
0answers
75 views

How to convert length in Decimal degrees to meters programmatically?

I'm new to qgis and I want to find the length of some roads in a map. So I used the following code, from shapely.wkb import loads def getLength(): layer = ...
1
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0answers
27 views

Add WMS in QGIS gives an error with Map request failed [error:Host http not found url:http://http//

I got an URL from a friend who is working with Oracle MapBuilder. http://[IP]:11188/mapviewer/wms I tried to get the service via ArcMap and it was working. Then I tried my beloved QGIS and there is ...
2
votes
1answer
25 views

Meaning of r.viewshed output numbers in QGIS?

I have completed a r.viewshed analysis of a point in GRASS7. I have imported the arising Geotiff into QGIS and when viewing the layer in the layer window (after expanding the +) I am presented with a ...
3
votes
1answer
121 views

QGIS Calculate flow length path

I am trying to replicate my Erosion model in ArcGIS for Desktop to QGIS 2.4. I try to calculate in QGIS the upstream distance along the flow path for my agricultural field. I do the equivalent in ...
1
vote
1answer
20 views

Console application in .NET incorporating QGIS tools

I am working on a project where I want to build a standalone application in .NET using QGIS tools. Is there any option like the ArcObjects SDK for .NET? Please help me on this.
3
votes
1answer
55 views

QGIS Topology Checker select errors

I have used the Topology Checker plugin in QGIS to create rules to identify errors in my layer. For example, I have used it to search for all overlapping polygons. This plugin is great for finding ...
0
votes
0answers
25 views

how to add different data frames in QGIS? [duplicate]

![enter image description here][1]how can i add different data frames in QGIS and show all data frames in single map like we add different data frames in ARCGIS and in single map we show these data ...
2
votes
1answer
82 views

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. ...
3
votes
1answer
69 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 ...
1
vote
0answers
27 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 ...
1
vote
1answer
61 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 ...
5
votes
6answers
273 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 ...
0
votes
1answer
32 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 ...
0
votes
1answer
32 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 ...
0
votes
0answers
20 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 ...
2
votes
1answer
67 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
votes
1answer
38 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 ...
0
votes
2answers
89 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 ...
2
votes
0answers
58 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 ...
1
vote
1answer
24 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 ...
1
vote
0answers
39 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
votes
0answers
53 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
votes
1answer
50 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
votes
1answer
45 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
votes
1answer
41 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 ...
2
votes
0answers
47 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 ...
1
vote
1answer
72 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 ...
2
votes
2answers
52 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 ...
0
votes
2answers
60 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 ...
3
votes
0answers
29 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 ...
1
vote
0answers
32 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
votes
2answers
100 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 ...
0
votes
0answers
37 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 ...
3
votes
2answers
705 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
votes
2answers
47 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 ...
0
votes
0answers
16 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
votes
1answer
28 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
vote
2answers
33 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 ...
1
vote
1answer
59 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
votes
2answers
39 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.
2
votes
1answer
52 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 ...
1
vote
0answers
54 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 ...
2
votes
1answer
23 views

Direction of movement with points2paths in QGIS

I have a data set containing ship movements. I used the Points2paths plugin in QGIS to connect the points with the ship's names as factor and the time the signal was picked up as sorting value. Now I ...
3
votes
2answers
60 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 ...
0
votes
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
votes
1answer
41 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 ...