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

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3
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140 views

Batch export to shapefile by attribute field in QGIS

I have a project in QGIS where I am creating a map of plants over a large area. I want to take the "Genus" field (of which there are 100 hundred values) and essentially create 100 shapefiles based on ...
3
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66 views

Resampling air temperature gridded data to sub-grid resolution

I'd like to obtain a 30-m resolution gridded dataset of air temperature from the ~1km gridded data of WorldClim, of Hijmans et al., 2005) for a mountainous region. The easiest procedure (I thought ...
3
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47 views

Overriding the QGIS Feature Dialog

We are developing a QGIS plugin and would like to override the QGIS Feature Edit Form with our own Dialog. Have explored using setEditForm and setEditFormInit, but the init process appears to want to ...
3
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0answers
48 views

Is there a limitation on the numbers of layers that can be displayed in QGIS?

I have been looking for an answer to this question for the last several weeks, so hope that someone here has encountered the same issue and has a viable solution to my problem. I am currently using ...
3
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114 views

Create vector grid from canvas using script

I've modified "Hex grid from layer bounds" script to my need. Just added cellsizex and cellsizey. Changed the hexagonal - 3 to "1" to make it as a square grid. Is it possible to include an option to ...
3
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154 views

ISOdata classifier in QGIS?

Is there a function that produces an ISODATA unsupervised classification in QGIS? The only unsupervised classification function I can find is a KMeans.
3
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0answers
83 views

Connecting QGIS 2.x to Firebird Database via ODBC?

I tried to connect a Firebird Database in QGIS 2.2 and 2.4 via ODBC to a database and get following error message: Unable to initialize ODBC connection to DSN for SYSDBA/masterkey@Akdees ...
3
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0answers
133 views

Performing buffering and intersection with script in PyQGIS

I wrote a script that performs the intersection of two layers: The first Layer -> layer1, represents the rivers The second Layer -> layer2, represents a set of circular dots distributed in a ...
3
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0answers
742 views

QGIS 2.4.0 Mac Yosemite compatibility

I just upgraded to the Beta 2 version of MacOS 10.10 ("Yosemite"). I'm getting an error when I try to "drag and drop" shape files into QGIS. I'm running QGIS 2.4.0, GDAL 1.11, and MATPLOTLIB 1.3.1. ...
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201 views

How to calculate percentages using QGIS field calculator expression?

I am new to QGIS. I am wanting to calculate a field using other fields and some operators. Here is my expression: case When "RVM_CAT" = 'B' OR "RVM_CAT" = 'C' Then ("PC1" /100) * "RE_ha" When ...
3
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178 views

Startup python script to re-join layers

In QGIS 2.2, there is a bug which involves using the JOINS properties on a vector layer (that is already being joined with several other vector layers) whereby the attributes are not fully loaded. ...
3
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27 views

Refreshing “layer render order” widget

i made changes in the render order of my map canvas using a : qgis.utils.iface.mapCanvas().setLayerSet(a) "a" being a list of QgsMapCanvasLayer My code is working as expected (i see result on map ...
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229 views

Creating one DEM from multiple ASC files

I am struggling with this several days and now its time to ask how to do it in QGIS. I have very detailed 27 ASC grid files with overall size of 9 GB created from 1m contours of large area (600 m2). ...
3
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0answers
59 views

Option for 360 degree movie embedded in Open Source GIS software?

Is there any Open Source GIS software available to embed 360 degree movies with the map? For a COTS example, there is the Active Link Vision (ALV) extension for ArcGIS from IWANE.
3
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94 views

IS it possible to run GRASS commands in the QGIS graphical modeler?

I have a geoalgorithm set up in the graphical modeler and everything runs except for the GRASS commands. It is really frustrating because when I execute these commands on their own they work just fine ...
3
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291 views

QGIS API - Print Composer Template produces empty map?

I have a print composer template which I'm trying to populate with different subset queries from a CSV-derived vector layer using the Python API. However, all the output PDFs contain everything except ...
3
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54 views

access point layer representation in qgis with pyqgis

I am exporting the style of a categorized point layer with qgis: unfortunately my code only extract the size of the symbol in the definition of the properties of the layer but not the ...
3
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0answers
176 views

How to export data from sql server into shapefile in the decimal format in QGIS 2.4?

The last couple of days, I have been working on exporting data from SQL to a shapefile in QGIS 2.4. While converting into a shapefile, the data type changes automatically from Float to Integer in the ...
3
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43 views

Looking for a QGIS solution to make aerial imagery ArcSDE compatiable

Would like to avoid having to use 3d Analyst and use free raster tools in QGIS or elsewhere to make aerial rasters ArcSDE compatible. This 18 page work flow is what I am trying to use. Any suggestions ...
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488 views

Connecting ArcSDE to Quantum GIS for dummies?

I really have a need to be able to connect to and edit ArcSDE data in Quantum GIS. This question has been asked before and apparently is possible, but the instructions are just not specific enough ...
3
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225 views

Why does multi-threaded rendering not use all the CPU potential in QGIS 2.4?

I have just downloaded QGIS 2.4 which is great and ran some tests. I have enabled the multi-threaded rendering but it seems that the program do not use all the potential of my CPU. Attached pic shows ...
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69 views

How to find the minimum number of inspection points?

I am working on a pipeline inspection project and there is a high liklihood that some inspection tool deployment/retrival station will need to be installed on the pipe network. the problem is ...
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225 views

How to fix “Raster layer: Provider is not valid” error when loading PostGIS rasters?

I compiled and installed the current QGIS master as usual and I imported some raster data into my postgres 9.3 database with postgis 2.0.2 extension. Whenever I try to import the raster data into qgis ...
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77 views

Using Field Calculator to Convert Data Type In Field

I am trying to convert a field that is listed as "String" because it was imported into QGIS as a CSV (rural poverty population percentages by county in NC). I need to convert the percentages field ...
3
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217 views

Does QGIS support .sld style files for raster layers?

I'm currently looking at the documentation for geoserver, and I'm trying to load a raster and .sld file in QGIS to see if I can edit .sld files for raster layers. The .sld and raster are located here: ...
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522 views

How to use the linear referencing plugin?

I need a guide how to use this plugin properly, I'm a newbie on PostGIS and I'm trying to use the linear referencing plugin of QGIS. I've created a database on postgreSQL with the postGIS extension ...
3
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101 views

Creating a new raster based on pixel value of original raster using raster calculator but new layer is not evident

I am trying to create a new raster based on a current raster (w001001 - NVIS) which has one paletted band, with palette values ranging from 1 to 29, with each palette/value representing a vegetation ...
3
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182 views

Accessing existing instance of qgis from stand-alone python script

For my own data analysis pipeline, I am running a split screen setup with iPython notebooks on one side, generating variables from source data, pushing them to a csv file which qgis then reads/joins ...
3
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148 views

Creating water surface from vector line in QGIS

I want to create a raster surface representing the flood level in a creek based on output from a 1D hydraulic model. I receive a 3D profile of the water surface in a creek line as a 3D Polyline ...
3
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0answers
184 views

QGIS Select Single Feature not correct in attribute table

For some reason, QGIS is not displaying the correct row of my data when I click on a feature with "Select Single Feature" or even the other select tools. I have a point database linked from mysql. ...
3
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63 views

How to create a custom enterprise QGIS installer with plugins and symbols?

I am looking at installing QGIS at a company level. I would like my installer to install specific plugins, and add our company map symology. Are there any ways to do this? I have seen post about ...
3
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195 views

How to create a chart of the altitude of points?

I am using shapefiles with basic informations 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 ...
3
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155 views

Handling non-spatial data for QGIS projects with Camelot

Most of my projects include data which is non-spatial or which is point data and can be managed by a regular relational database. Previously I found Manifold and ms-access were a good combination ...
3
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104 views

Is Dynamic Traffic Format supported by QGIS?

I have to merge (Dynamic Traffic FORMAT) DTF file into QGIS. This data is only available from NAVTEQ or TOM TOM. When I have searched ArcGIS network analysis tool, there is a clear option for adding a ...
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169 views

QGIS does not read ESRI Geodatabase correctly

I have a geodatabase from the EPA that does not seem to me reading correctly with Quantum GIS. When I open the attribute table the first two columns have the same data. The first column is CERCLA_ID ...
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255 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 ...
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131 views

Can extracting raster values work in polygons' CRS without raster resampling?

I am trying to extract raster values using polygon layer with different CRS. Raster is in WGS84 (EPSG:4326) and the polygons in UTM (EPSG:23031). 1. If I want to work in the projection of the ...
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0answers
138 views

Why are my raster mean and standard deviation -1?

I have a set of about 25 rasters whose descriptive statistics I have been examining. The data in the rasters were calculated in Python and the rasters were created using Python-GDAL. In all but one ...
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35 views

Why are there changes in location when printing inserted points?

Añadí una capa de texto delimitado por comas y luego agregue una imagen satelital de google earth. Realizo un diseño de impresión y al imprimir cambia la ubicación de los puntos en varios metros. Cual ...
3
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0answers
435 views

Error in uploading data in QGIS cloud

I want to publish my .shp file using QGIS Cloud plugin. I signed in to qgiscloud.com (free). On create new database it will auto create dbname='fbeudp_mfaphk' user='fbeudp_mfaphk' ...
3
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0answers
76 views

How to analyze the signatures for a Landsat clasification with Sextante in Quantum Gis

I’m defining my training data for a Landsat classification. I´m digitalizing the polygons with the field data in QGis and I want to analyze the signatures of the Landsat images to avoid errors. In ...
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102 views

Can layers from Spatialite db be used as input for a Sextante model?

I'm trying to build my first models in SEXTANTE and already fail at the start. It seems not to be possible to add a vector layer which derives from a database. Orginally, the layers are from a .mdb. I ...
3
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0answers
128 views

Is there a tool for automated quality assurance for vector data captured on raster data?

I wonder whether is any tool(or script) in ArcGIS or QGIS which allows to make an automated quality assurance for vector data captured on raster data? vector data on binary raster:
3
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0answers
152 views

How does Zonal statistics handle pixels that are on the border of the polygon?

I am using the plugin zonal statistics to calculate the sum of the raster cells within polygons. How does this plugin handle pixels that are on the border of the polygon, are those cell values ...
3
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0answers
363 views

How to import PostGIS layer with geography type to QGIS?

I tried to import in QGIS a layer from a PostgreSQL table with a geography type column created through the extension PostGIS. I noticed that QGIS doesn't seem to like the geography column... Here ...
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0answers
817 views

How to join data from a CSV to a shapefile using QGIS

I'm new to GIS and new to StackedExchange. I need help joining a CSV of Accessibility data to a LSOA shapefile in QGIS. The process explained here does not work for me and I don't know why. The ...
3
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0answers
191 views

How to achieve better Dissolve results?

I applied the Vector>Geoverarbeitungswerkzeuge>Auflösen (Dissolve) on a zoning plan (see picture zoning plan). I used the attribute village name as the dissolving criteria. The resulting geometry for ...
3
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0answers
271 views

How to Create a Vector Field from Separate u and v Data Files?

I am using Quantum GIS and trying to create a vector field using data from two separate netcdfs. One contains the u data, one contains the v data. Can this be done, and if so, how? Thanks. Jason
3
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0answers
338 views

Building Qgis-1.8 on Scientific Linux - a sip error occured

I'm on Scientific Linux 6.3 and after trying to build Qgis 1.8 fter "ccmake" I got the error: [ 89%] Built target translations [ 89%] Generating analysis/sipanalysispart0.cpp, ...
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0answers
125 views

Why doesn't Polygonizer copy the line ids to my polygonized shapefile?

I am trying to convert a line shapefile into a polygon shapefile using Polygonizer plugin, and when my new polygons are created all the cells in my id field are "Null", although I have clicked "copy ...