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

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10 views

Calculating “sun time” on areas with high mountains? Topography available

I'm wondering how to proceed if you want to calculate how a location on land will get direct sunshine at a given time on a given date (compared being in the shadow of the mountains)? The area is very ...
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1answer
12 views

Geocoding - looking to identify county from list of zipcodes

Using QGIS, how do I find county of an associated zipcode? I have zipcode for each point, however, I do not have a street address. I am hoping to aggregate my data to the county level using the ...
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0answers
10 views

QGIS: is the connection with ArcGIS “mapserver” still working?

I would like to add the Ocean Basemap to QGIS. I also found the other posts and I followed this procedure: http://hub.qgis.org/wiki/quantum-gis/Arcgis_rest Hovewer when I put in the Python console ...
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0answers
7 views

World DEM vs ASTER Digital Elevation Models accuracy

I use DEM essentially to create surfaces on AutoCAD Civil 3D and then to create terrain profile views. I have been using mainly ASTER imagery from which I extract 2m contour lines in QGis and then ...
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0answers
9 views

pyqgis, features geometry type changes to unknown after copying to anoter layer

Im copying a subset of features from a shapefile based QgsVectorLayer (polyline type shapefile) to a memory based QgsVectorLayer('LineString', layername ,'memory'): ...
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10 views

QGIS 2.8.2 Road Graph doesn't accept road network vector

I'm using the Finnish official Department of Transport's "digiroad" road network vector file, which has all kinds of roads, cycle paths etc on it, but I can't use Road Graph on it. If I create a new ...
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1answer
12 views

pyqgis write vector layer as tab delimited txt file

I'm using the following QGIS 2.8 Python code to save results to a txt file QgsVectorFileWriter.writeAsVectorFormat(inputLayer, "D:/dstest/my_csv", "CP1250", None, "CSV",True) I would like to be ...
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2answers
29 views

How to close a polyline in QGIS while digitizing?

We need to work on a line layer where some features are closed and some are open. The closed features need to be closed perfectly, so that the first and the last point of the polyline perfectly match. ...
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16 views

Can I mimic the “open” action with python and manipulate the field content used for the action?

I am using QGIS actions (type: "open") to link ECM searches to objects on the map. The basic syntax is very simple: protocol://searchterm1=[%"field1"%]&searchterm2=[%"field2"%] However, some ...
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0answers
17 views

Quick way to select by attribute and zoom to selection in QGIS

I need to visually control hundreds of points in a layer on top of aerial photographs. Using the attribute table, selecting (with column filter expression) and zooming manually is cumbersome - so I ...
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1answer
19 views

Taking a long time to load tables from oracle to QGIS

My workplace has an oracle database with a very large number of spatial tables. Therefore, it takes a long time to load the oracle connection in QGIS. Does anyone know how this could be speed up?
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0answers
26 views

Create new attribute ranking polygons by size in QGIS

I'd like to create a new field in the attribute table which gives the rank of the polygon by size. For example, the polygon of the largest size would be rank 1 and the smallest rank N. I was hoping ...
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0answers
19 views

GeoJson and D3.js multipolygon

I have this geometric shape file, so no map of a city. I store the two Shapefiles in a GIS database as a geometric form. Now, I want to visualize the geojson data. I created the GeoJson data ...
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0answers
15 views

Are there limitations for QGIS Composer images larger than 32768 pixels?

We are outputting a map file with composer : size 45,312 pixels width and 4,352 pixels height in TIFF and PNG format. The map is calculated but in the file we have only 32,768 pixels width show, the ...
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1answer
30 views

Save a table in ascending order in QGIS [duplicate]

Is there a quick way to sort an attribute table in QGIS in ascending order permanently and save it? My third column is an integrer, of course if I clik on the header the table will be sorted in ...
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0answers
9 views

Creating Shape by Density Criteria using QGIS?

I have a map with points plotted. Is there a way that I can make a circle of a certain radius (let's assume 10 miles) if the density of points in any given 10 mile radius is over a certain number?
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16 views

Why does the “local maxima” module in SAGA GIS put so many “maxima” points on lakes and plains?

SAGA GIS puts too many maxima points on plains and lakes. Why does it happen? Is there a way to avoid this? It's not really a big problem (the value is correct) except for the size of the SHP files in ...
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0answers
31 views

Script in PyQGIS to create a shapefile

I'm having some trouble applying my Python skills to develop some scripts in PyQGIS. For me it's far simpler to write it in ArcPy, but then again I wouldn't get that much satisfaction after finishing ...
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0answers
20 views

Radius settings under IDW interpolation Qgis [on hold]

I have a point data set that I want to interpolate in Qgis. I use the Grid (interpolation) under: Raster- analysis- grid(interpolation) - IDW. There is several things to tweak the output with that I ...
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1answer
14 views

Irregular (increasing) scale bar in print composer of QGIS 2.8

Is it possible to display irregular - increasing values in scale bar in print composer? For example: 5, 20, 100, 250.
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0answers
7 views

Range problem in QDoublespinbox for different projections of data in QtDesigner\python

I have two QDoubleSpinboxes that updates the value of latitude and longitude of a point respectively. The data is in the CRS "EPSG:32643 - WGS 84 / UTM zone 43N" I had also set range of the ...
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0answers
32 views

Merge vector layers problem with german names (ä, ü, ö…)

When I'm trying to merge (saga merge layers tool) some shape files I get an error log 'ascii' codec can't decode byte 0xfc in position 91: ordinal not in range(128) See log for more details ...
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1answer
25 views

How to suppress polygon overlapped areas in QGIS?

Is there a way to remove polygon overlaps using QGIS ? If so, would it be possible to remove the overlaps area of the biggest polygon (having the greatest surface) ?
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0answers
23 views

QGIS Raster Calculator giving a NaN output

This is my first time using QGIS and I am trying to use it to generate NDVI maps from data captured by my UAV. However when I apply the NDVI formula in the raster calculator using my NIRGB image the ...
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1answer
26 views

QGIS Python Scripting permission denied

I've just started a Python Scripting tutorial on QGIS. The problem arrives right at the end, when I have to use this script: output_file = open('c:/Users/Ujaval/Desktop/airports.txt', 'w') for f in ...
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0answers
16 views

Masking Labeles in the Compositor in QGIS 2.8.1

i am looking for a way to remove/mask out the Labels that are under a composer Element, wich i moved in front of my main map. Is there a way to do this? I tried the mask addon, but it only seems to ...
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0answers
19 views

Remove no-data values from a raster using raster calculator

Can someone please tell me what the formula is to remove no data values from a raster in QGIS? I have a large DEM .tif file and need to remove the no data values. Is it better to use SAGA to perform ...
0
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1answer
26 views

Function to merge geojson and csv data in R

I have been using merge() to merge my geojson file with csv data in R. My codes are as follows: map@data <- merge(map@data, csvdata, by.x="ID", by.y="ID") However, after exporting the geojson ...
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0answers
26 views

QGIS web mapping using WMS server? [on hold]

I want to publish my QGIS map. How to make it using WMS as server and PostgreSQL as my database?
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0answers
20 views

Is it possible to use GPS navigation with track up in QGIS 2.8

Can we have a rotating map while navigating with a GPS so our track is always pointing up? Just like a car GPS
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3answers
36 views

Create a reference number (id) based on x coordinate in QGIS

I would like to add a reference number to a point table. I would like this value to increase as I move from west to east across my data. So the values read 1 to n from west to east. I have an ...
1
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1answer
20 views

Receiving NULL values from Point Sampling Tool in QGIS

I am using QGIS 2.8.2. My project includes a raster layer of flow depth representing the output from a flood simulation (.DAT file). It also includes a vector layer of points representing the ...
0
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1answer
25 views

where to download gdal_polygonize.py?

I am trying to help out a friend of mine. She learnt GIS in school in the past using ArcGIS but has recently installed QGIS package on her Mac OSX. When she tries to render raster into shape file, ...
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1answer
20 views

Spatialite table column is function in itself

GOAL: I'm trying to filter all the 1's in a spatial boolean operation in Qspatialite, the spatialite plugin for QGIS. ATTEMPTED SOLUTION: My solution is to perform the boolean query first, export the ...
1
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1answer
75 views

Excel XLSX data with coordinates displayed as points

I am preparing a course for QGIS newbies, which includes handling Excel spreadsheet data in QGIS. It's so easy: Just drag an XLS, XSLX or CSV from Windows Explorer to QGIS! For data with no ...
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0answers
15 views

Grass functions (for example, r.li) on QGIS Processing Toolbox

I need to know if it is possible to add other functions, such as r.li to Processing Toolbox. Thanks.
2
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1answer
33 views

Is it possible to georeference raster stored in Postgis?

I'm looking to store a huge raster aerial image (400 Gb) into Postgis, but before storing it i like to know how i could georeference or rectify raster stored in postgis ? is there any Qgis plugins ...
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0answers
17 views

QGIS 2.8.1-Wien snap options does not show “avoid int” dialog box

I am trying to digitize a set of adjacent polygons in QGIS 2.8.1-Wien, runing under Widows 8. When I go to Settings > Snap options my vetor (polygon) layer does not show the "avoid int" box. Can ...
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2answers
32 views

How to coincide two geometries which has difference in positioning?

I have two vector layers one representing countries and other representing states. I have states which is slightly dis positioned so that it is not exactly not coinciding with the country.Algorithm ...
2
votes
1answer
23 views

What are good practices for troubleshooting QGIS freezing/stalling trouble?

I've been using QGIS for more than a year now (currently using 2.8.2 on MacOS 10.10.3, but also in Windows XP via VirtualBox for troubleshooting) and the application has been freezing and stalling ...
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1answer
44 views

Cannot edit polygons in Qgis

I have a google Layer map on top of which I have added a raster layer of Image and then mapped image coordinates from Google layer. I made transparent (75%) image map layer and now mapping and ...
0
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0answers
21 views

Fill raster “gaps” (No-Data cells) by means of different raster [on hold]

Let's assume I have two (or more) rasters with different resolutions which describe the same area. Since my question is so general, I thought that I will easily navigate answer, but I can't. This is ...
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5answers
107 views

How can I create a 10m DEM from the 30M DEM with me?

I am not regularly working in raster analysis. I have got a 30M DEM with me and I would like to create a 10 DEM out of that. Is it possible to do this using QGIS? and How? EDIT: I have got the ...
0
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1answer
33 views

Geographic crime profiling in QGIS?

How would you implement geographic profiling in QGIS? There doesn't seem to be any pre-existing plugins and my Python skills are not quite good enough to implement it myself. Specifically, Rossmo's ...
2
votes
1answer
22 views

How can I convert climatic text data to raster in QGIS and ArcGIS?

I have been provided with text (*txt) formatted, tabular climatic data. How can I convert climatic text data to raster in QGIS and ArcGIS? In addition to tabular data, the following information is ...
1
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1answer
38 views

QGIS: why does clipping a raster alters cell size?

Using QGIS V 2.2.0 (OS-Windows 8), I need to prepare raster files (ESRI ArcInfo Grids) to be later used in a species distribucion model using MaxEnt. Each of the original raster files (environmental ...
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3answers
52 views

Is there any way to freeze the layer names in the TOC?

I would like to freeze the names of layers in TOC. Is there any way to do this via QGIS config or PyQGIS? I´m using QGIS Wien.
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0answers
12 views

How to show a QGis map in Qt/C++ custom widget with QgsMapCanvas?

I'm trying to add a QGis map in Qt/C++ widget using QgsMapCanvas, but I have some problems... I'm working with the following environment: - Ubuntu 12.04 - QGis 2.8.1 - Qt Creator 2.4.1 (based on Qt ...
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0answers
23 views

Attribute error with FileGDB

I have a large ESRI file geodatabase, that I loaded into QGIS with no problems. If I look at the attributes tab in the properties dialog, the fields are as they should be. One of the fields is ...
3
votes
4answers
91 views

Checking if polygon fits inside another polygon using ArcGIS or QGIS?

How do I check if one polygon fits inside another polygon? Furthermore how do I automatically check if one polygon fits in other polygons of my shapefile? I have a shapefile with thousands of ...