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

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1answer
1k views

how to generate NDVI with multi channel images?

I have a 6 channel proprietary camera and I need to create a NDVI map. I created a map from each band, so now I have 6 files each one on a different band width. How can I proceed now? I am using QGIS ...
2
votes
1answer
300 views

QGIS has an automatic way of finding the LS factor?

I wonder if is possible to calculate LS (soil erosion) factor automatically in QGIS? Or at least a way to calculate the length slope?
2
votes
1answer
36 views

How to compute areas where the value in one layer is smaller than in another layer?

I have two vector layers, one contains actual values (in this case % cover of native species), the other contains target vales of the same attribute. the polygons are not always of the same geometry. ...
2
votes
1answer
156 views

geting geograpic locations from an address list

I have a table with 150 addresses. I would like to automaticly generate a point shapefile/PostGIS layer from all of them. Is that possible in any way or do I have to search for every single address to ...
2
votes
1answer
572 views

How to get the Parameters for a Lambert conformal conic projection CRS in QGIS 2.6

I am currently having some trouble adding the CRS to a vector file that I want to re project to WGS84/UTM. The shapefile is using Lambert Conformal Conic Projection; ITRF92 horizontal datum and GRS ...
2
votes
2answers
396 views

How to host the results of qgis2leaf on google drive?

I am wondering how to host the results of the plugin qgis2leaf on google drive to create a free hosted webmap? Here is an example: https://39b425ec138a1e68ecbac84487470661e6b8b943-www.googledrive.com/...
2
votes
1answer
938 views

How to develop c++ standalone QGIS C++ Application

I want to integrate QGIS in QT\C++ application. I try to write basic C++ apllication to render map and build it using MSVC 2010. class PostGisViewer: public QMainWindow { public: PostGisViewer(): ...
2
votes
1answer
265 views

How to convert a RGB tiff into pseudocolor with GDAL etc?

In QGIS I have made a singleband pseudocolor image out of one of the bands from a RGB GeoTiff. I choose one band and then make a linear color interpolation (see attached image). I now want to do ...
2
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1answer
166 views

What is the expression for getting a subset of characters in QGIS Field Calculator?

I have a column of 10 character names e.g. L3NAM1988K. How can I delete the first 5 characters and the last 1 character using an expression in the QGis Field Calculator?
2
votes
2answers
208 views

With QGIS Plugins/PluginBuilder, how to prevent 2nd instance of Plugin from starting

I am using QGIS 2.6.0, with PluginBuilder 2.0.3 [checking the version, I just noticed that the 2.1.0 update is available] I am writing a plugin; it installs and runs. While running, I am able to ...
2
votes
2answers
176 views

Using QgsRasterCalculator

I'm trying to make a sum of n rasters and create a new one using QgsRasterClaculator, the problem is, every time the code reaches processCalculation, it makes QGis close and create a dump file. I don'...
2
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2answers
299 views

Is there an algorithm for transforming from CGCS2000 to WGS84?

Is there an algorithm that supports transforming from CGCS2000 coordinate to WGS84 coordinate? CGCS2000 is China Geodetic Coordinate System 2000. Any advice would be thankful!
2
votes
2answers
148 views

fit a wrap column in the print composer QGIS 2.4

i have an attribute table in the map composer, and the field i want to see is quite long...so i wrap it. but the field width is not fitting this new length. how can i do that. is qgis prepared to do ...
2
votes
2answers
401 views

Looking for guidance to create a hydrological map with QGIS and/or GRASS

I have QGIS and GRASS installed . Basically i need this program for making maps something like this: https://www.youtube.com/watch?v=5HuPX7JS7ZA I downloaded DEM from http://glcfapp.glcf.umd.edu:8080/...
2
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2answers
198 views

Versioning in QGIS?

Are we planning to have in QGIS implementation of Versioning like ESRI. How that can implemented? There is a general need for the the implementation where QGIS is used for planning and planned design ...
2
votes
1answer
268 views

Generate territory polygon from sets of points

I'm looking for a simple way to generate contiguous "territories" from sets of points. Say, points A, B and C are in territory 1, and D, E and F are in territory 2, then generate polygons that lie ...
2
votes
1answer
216 views

Convert Layer to Shapefile without losing Feature definitions

I have created a worldmap with custom defined Features, representing State/Zip-Code sales areas. I want to convert them into a Shapefile, so I can convert the Shapefile into a polygon definition file ...
2
votes
1answer
129 views

QGIS Technical problem in 'Extract nodes' command

I am trying to create a layer of nodes from an existing layer of line. For this I am using Vector> Geometry Tools > Extract nodes I, first, select the 'Input polygon vector layer' and then select ...
2
votes
1answer
894 views

QGIS 2.4 dissolve doesnt work properly, why?

I am used to work with ArcGIS and now I started to explore QGIS more. I have problem with dissolve function. I have administrative borders and I would like to dissolve them into higher administrative ...
2
votes
1answer
38 views

How to style a Vector layer in QGIS using a numeral of an attribute

I have a simple vector layer in QGIS that I would like to style with numerals based on the ID attribute. For instance, point with ID 1 will show up as the numeral 1. Is this possible with default ...
2
votes
1answer
129 views

QGIS atlas-generation: Is it possible to preserve the map section?

My aim is to generate several maps with the atlas function in QGIS 2.4 (win7 64) showing the same map section and scale. However, each generated atlas map shows a slightly different map section (not ...
2
votes
1answer
124 views

Adding attributes to an existing shapefile [duplicate]

I have a shapefile made of buildings, each one of them characterized by some attributes. I need to add some attributes contained in a .dbf file. The two files have in common the attribute "ID", so the ...
2
votes
1answer
648 views

Combine two grids with a small area of overlapping pixels to a new raster in QGIS/SAGA

The first grid is 1 byte and the second is 2 byte. The new raster should have a blended transition. How can i do this?
2
votes
2answers
394 views

Select part of a polygon on one side of a line QGIS

I have a line shapefile of the outline of a water body. It was created by conversion of the polygon to line. I am looking to add a layer of 500m standoff from the shore into the lake. I have added ...
2
votes
2answers
144 views

Custom projection problem with proj.4

I have some vector files that come without projection. So I have to define my own projection in QGIS. The information that comes with the data reads as following: Projection: Lambert Azimuthal Units: ...
2
votes
1answer
90 views

Joining QGIS extent table with shapefile

I used QGIS to find the extents of a list of features from a census boundaries shapefile. I used Vector - Research tools - Polygon From Layer Extent, which creates a new shapefile with a table of ...
2
votes
1answer
170 views

QGIS Plugin development version compatibility

At this time latest QGIS version is 2.4 , QT Version is 5.3.1 and PyQT5.Are these version compatible with each other ? Once QGIS 2.4 is installed , how does one know which version of QT and PyQT(and ...
2
votes
2answers
110 views

How to get for a given pixel the values from different overlapped rasters?

I have a few rasters representing different soil properties, like soil pH and sand content. The rasters overlap perfectly, have the same dimensions and same coordinate reference system. I would like ...
2
votes
1answer
627 views

Possible to set an attribute field to update automatically based on another field?

If I have 2 attribute columns and I wish to change certain values, is it possible for the second attribute column to automatically update its values based on an expression? Example: Age | Status 10 ...
2
votes
2answers
170 views

How do you make an unclassed choropleth in QGIS 2.x?

How do you make an unclassed choropleth in QGIS 2.x? I'm using 2.4 and can't find an option in a layer's Style tab like the continuous color option that seems to have existed in QGIS 1.x. I'm curious ...
2
votes
1answer
384 views

QGIS show gdal_polygonized file in EPSG:54004 instead of EPSG:3857

I am polygonizing a TIFF with the gdal_polygonize.py and the resulting Shape is shown in QGIS in the wrong projection - EPSG:54004 instead of EPSG:3857. I have a TIFF in EPSG:3857 and polygonize it ...
2
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2answers
142 views

kml does not overlay correctly in QGIS

In QGIS, when I insert a kml contour that was created in Google Earth, it appears misaligned in respect to all the other layers. Note in this image how the red contour is moved upwards with respect ...
2
votes
1answer
174 views

How to convert unix time to qt time type?

How can I convert unix timestamp to qt time type using qgis field calculator? I would like to avoid importing my table into excel and convert the timestamp to qt time type.
2
votes
2answers
1k views

Using QGIS to access data delivered by ArcGIS for Server?

Can I use QGIS to access data delivered using ArcGIS Server? The following servers don't seem to be compatible with QGIS http://www.topofthesouthmaps.co.nz ​http://gis.wcrc.govt.nz/arcgis/rest/...
2
votes
1answer
670 views

SPOT 2-5 convert DN to TOA using QGIS

I'm new to QGIS and I would like to convert SPOT(2-5) images from DN to TOA. How do I go about doing this? I've an idea of how to do it for Landsat images however I'm not sure about SPOT.
2
votes
1answer
448 views

Delete duplicate polygon nodes with PostGIS

I'm trying to delete duplicate nodes from a shapefile with QGIS, but after running the tool to delete it, nothing happens and shows the same errors. I thought that maybe importing to postgis could be ...
2
votes
1answer
1k views

Wind Farm Viewshed Analysis

I am new to GIS and I want to run several view shed analysis operations for wind turbines located in the North of England I have installed QGIS and have the GRASS r.los plug in installed for line of ...
2
votes
1answer
188 views

QGIS Filters and Queries

In QGIS is there a way to filter a layer using the Query Builder to show all values which include a particular phrase. For example I have a list of organisations and I want to filter all those which ...
2
votes
2answers
2k views

Creating New Layer After Sorting Attribute Table using QGIS?

I have been self-teaching myself some open source GIS. I downloaded QGIS and have been following this four part tutorial - http://www.youtube.com/watch?v=XUD6zcNGl4A&list=UUZkLX9x-...
2
votes
1answer
682 views

Merge multiple linestring features into a single multilinestring

Using QGis or ogr2ogr how do I convert a vector file containing multiple linestrings features into a single multilinestring feature? At the moment I've been doing this manually by converting the data ...
2
votes
1answer
178 views

CSV handling in QGIS?

I am using QGIS 2.4.0 and sadly it seems that QGIS imported csv files are somewhat bugged. I cannot use imported csv files the same way as shapefiles. It seems that sometimes it is easier to import ...
2
votes
1answer
173 views

How do I save as .osm in QGIS?

The directions in http://docs.qgis.org/2.2/en/docs/user_manual/osm/openstreetmap.html#saving-osm-data seem to have been written before the OSM plugin was merged into QGIS proper. I can locate no OSM ...
2
votes
2answers
149 views

qgis raster style 'no data value' checkbox is ignored - what's a good workaround?

See bug report filed here: http://hub.qgis.org/issues/10236 Note the initial bug report got 'fixed' but that fix introduced this new error, so the issue was reopened a few days ago. Anyway, it ...
2
votes
2answers
160 views

How to get the Measure Line in Yards (not Feet)

I'm using Qgis Dufour 2.0.1 and the Openlayers Plugin for images. I'm working on a golf course project where everyone thinks in yards. I've tried different CRS (now working the State Plane Missouri ...
2
votes
1answer
3k views

How to change GDAL version in QGIS to get ECW import to work

I’ve previously been successful in importing ecw into QGIS 2.0 but the same methods (for example How to add *.ecw files to QGIS 2.0 on Windows?) have failed with a fresh install of QGIS 2.2 with ...
2
votes
1answer
1k views

Exporting geodata from QGIS to Esri File Geodatabase?

For a project I need to create a set of vector data that I think I could do in QGIS. However the customer demands that the final data set needs to be delivered in a Esri File Geodatabase. Is there ...
2
votes
1answer
55 views

How to display information when a certain dataset is loaded into QGIS?

I need to show the quality information of a dataset that was manually created by me, that is saved as a text file. The text file will "pop up" when the dataset is added into QGIS. I have no experience ...
2
votes
1answer
1k views

How to undo misclicks while drawing a polygon?

I'm trying to draw some polygons in QGIS 2.2 and I lose it, because everytime I misclick, I don't find a way to undo that point and start drawing again. I'm sure there's a way. Does anyone know it?
2
votes
1answer
469 views

Label all features of shapefile with PyQGIS

I have a problem when trying to label all features of a shapefile with a Python routine. If I open my shapefile in QGIS "by hand", and select a .qml with pre-defined label selection, the labels are ...
2
votes
1answer
498 views

Error: Algorithm not found

I wrote the following code to start using QGIS APIs. in a very short script seen below, the "Error: Algorithm not found" is thrown and "print processing.alglist()" is showing none. Any idea why this ...