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12
votes
0answers
679 views

How to reverse-georeference with QGIS?

I have a map with a "strange" projection (it's basically hand-painted, not an exact one). I can easily georeference it in QGIS using the Georeferencer plugin and the Thin Plate Spline transformation ...
10
votes
0answers
289 views

PyQGIS save raster as rendered image, then use GDAL tools on it

I have tried to use the code from QGis Save Raster as Rendered Image. i is a raster layer: pipelayer = i pipeextent = pipelayer.extent() pipewidth, pipeheight = (pipelayer.width(), ...
8
votes
0answers
151 views

How to access a deleted features attributes (before committing)

I have a signal setup for a feature deletion event on a layer: self.layer.featureDeleted.connect(self.feature_deleted) When I try and grab an attribute from the deleted feature on the slot, a ...
7
votes
0answers
263 views

Frontal Detection of sst & Chlorophyll image

I am working on sea surface temperature satellite images and looking for delineating gradients in open source on the basis of temperature. Is there any tool like Cayula and Cornillon front detection ...
7
votes
0answers
357 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 ...
7
votes
0answers
697 views

Grouping analysis of points to divide polygon into n number of sub-regions using QGIS?

I'm attempting to create n sub-regions from a polygon based on a cluster analysis of a bunch of overlapping raster layers (physical layers, eg: depth, currents, waves). Briefly, I can create a ...
7
votes
0answers
436 views

What to do about Geoserver WPS warning“ ”Could not get a ServiceInfo"?

This is the warning I am getting when I try to use this WPS service from QGIS, and the processing time is taking too long, but doesn't terminate. What might be the problem? 17 Oct 12:33:25 INFO [...
7
votes
0answers
691 views

How to get rpy2 for QGIS on OSX?

I am a new QGIS user, have installed QGIS on a Mac running Snow Leopard OSX 10.6.8 following all the instructions. QGIS seems to work well for everything other than when I boot up I get the message "...
6
votes
0answers
78 views

Development of a plugin which depends on an external Python library

I'm developing a Python plugin, the target is integrating into QGIS the functionalities of a PyPI Python library called 'elevation'. Is there an OS independent way of installing external Python ...
6
votes
0answers
103 views

Can a memory layer be used as an input and/or output with runalg?

Can a memory layer be used as an input and/or output with runalg? With runandload I get this to work: processing.runandload("qgis:mergevectorlayers","memory:bufferOne", "memory:bufferTwo", r"memory:...
6
votes
0answers
88 views

Perform QGIS modeler multiple raster calculations with data from external CSV

I need to perform multiple calculations on a set of rasters based on values in a CSV metadata file. I'm using the QGIS graphical modeler and can call a specific field in a CSV with the Table and ...
6
votes
0answers
91 views

Exotic Projections QGIS

I would like to use some projections in QGIS that I can't see supported directly. An example would be something like this conformal cube projection. http://www.csiss.org/map-projections/...
6
votes
0answers
77 views

Styling polyline to view which part is above another in self intersection using QGIS?

I need to view a polyline constructed from waypoints of a gps track, that has self intersections in curves, like an exit loop from a highway. I need to visualize it in a way that allow to know which ...
6
votes
0answers
327 views

Add vector tile sources to QGIS

Is it possible to add vector tile sources (using MapBox's protocol buffers format, or GeoJSON, or otherwise) to QGIS? If so, how? (My question is a bit similar to Can the new Mapbox Vector Tiles be ...
6
votes
0answers
329 views

Why is QGIS georeferencer much faster on Windows than Mac?

I just went from temporarily using a Windows 7 machine with 4GB of RAM and no video card as far as I know. I'm now using a mac with 16GB of ram, etc. Its a much more powerful machine. However, QGis's ...
6
votes
0answers
574 views

Printing/exporting WMTS tile layer with desired resolution / zoom level in QGIS

I have a project which uses WMTS and some vector layers in QGIS. I can freely zoom in and out, and tiles are refreshed with appropriate zoom level, just as expected. Now I would like to export part ...
6
votes
0answers
890 views

How to use the linear referencing plugin from QGIS with postGIS data?

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 ...
6
votes
0answers
334 views

QGIS: How to reverse vertex ordering in polygons

I am working with an Oracle spatial connection in QGIS through which I am accessing and editing a vector layer. I find that when I edit a geometry, the vertex ordering is reversed (to clockwise in the ...
6
votes
0answers
511 views

How do I install Orfeo toolbox and Qgis 1.9?

I'm having a lot of trouble getting Orfeo toolbox and Qgis 2.0 working. I followed the qgis wiki instructios, added the ppa, installed qgis 1.9 (it's beautiful, great work!). But when i tried to ...
6
votes
0answers
1k views

How to create point labels from midpoints of road polylines in QGIS?

Heres what i want to achieve: i have a roading polyline layer (singlepart ie has several features per road, grouped by an id field), and i want to (after merging the parts) find the mid point of the ...
5
votes
0answers
38 views

QGIS Renders Buffer Polygons from ArcGIS Feature Class Differently

I have a polygon feature class stored in an ArcGIS geodatabase. All of the shapes are buffers of a point layer created using the editor menu's 'Buffer' command. In ArcMap 10.3.1 the data looks like ...
5
votes
0answers
51 views

Automatically style raster using unique values in QGIS?

In ArcMap, it is possible to automatically calculate the unique values for a raster and then apply a different style to each unique value (see 1st image). However, in QGIS, I have to manually add ...
5
votes
0answers
97 views

How to fill composer map with canvas data and export composition as png using Python script in QGIS

I'd like to create a Python script in QGIS that will take some data (shp + tif, in my example), use tamplate Map Composer (from a file) and export created composition to a png image. With almost no ...
5
votes
0answers
56 views

See python script running while processing a task in QGIS?

Is it possible to see scripts running in Python Console - everything from tools and analysis vector to raster?
5
votes
0answers
62 views

SAGA-Inverse Distance Weighting in QGIS - How to Set Minimum Number of Points?

I am analyzing a postGIS point dataset in QGIS version 2.8.2, about 200k features total. To calculate weighted average values I am using the Inverse Distance Weighted interpolation technique. However, ...
5
votes
0answers
41 views

QGIS becomes non-responsive when adding jpg raster layer

When trying to add a raster layer (georeferenced jpg-files) QGIS becomes non-responsive. I have tested the jpgs and they are not corrupted, sometimes they appear and it works for a little while before ...
5
votes
0answers
145 views

How to speed up simultaneous working with PostGIS layers in QGIS?

we are working on one big layer at the same time (10-20 people). Some of us use QGIS 2.8.1 and the other 2.6. The user with 2.8 have a lot of crashes (QGIS). The 2.6 users don't have this crashes but ...
5
votes
0answers
77 views

QGIS Cross Section Profile Distance using Ellipsoid?

I am working with QGIS 1.8 and 2.6 and can't get any of the Cross Section Profile tools to provide the ellipsoid ("proper") distances. All the distances use geographic coordinates which are too long/...
5
votes
0answers
94 views

Generate a series of ellipses on a line

I am trying to create a series of ellipses (mocked up in green below) of defined dimensions along a line. I have got as far as generating regularly spaced points along the line that are attributed ...
5
votes
0answers
118 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 ...
5
votes
0answers
101 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 ...
5
votes
0answers
211 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 ...
5
votes
0answers
171 views

Is there a limit to the number of polygon points you can export to CSV in QGIS 2.4?

Using QGIS 2.4 I am currently importing a csv file with ~30,000 polygons (polygons in WKT format). I also have a United States shapefile. I have used the Clip function to get only the polygons that ...
5
votes
0answers
493 views

Weather conditions forecasting / interpolation

I'm trying to carry out weather conditions interpolations. I have information of 92 weather stations for 800,000 km2. As you can imagine the extension of land is huge and I need some kind or weather ...
5
votes
0answers
277 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. QGIS Version 1.8.0 (Lisboa) and GDAL/OGR 1.9.2 When I open the attribute table the first two columns ...
5
votes
0answers
265 views

How to write an address search plugin?

I am migrating some users from MapInfo to QGIS, and before they sign off on it, they want a very simple address search in the same way that we currently have one working in MapBasic. I;ve been having ...
5
votes
0answers
138 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 ...
4
votes
0answers
84 views

Raster calculator creates strange output

I am trying to combine two raster layers (one is nighttime satellite data, the other is the GPW population density data). I am using raster calculator to combine the two (the following is for a ...
4
votes
0answers
29 views

Using QgsNewVectorLayerDialog

I am using QgsNewVectorLayerDialog for taking user input for creating a new shape file. When the user clicks OK i am reading the inputs selected by the user using the following code. dlg = ...
4
votes
0answers
65 views

Connect data from two different layers

I'm trying to connect data from two different layers to combine them in one new layer and continue working with them. Let me explain that a bit more detailed: The first layer contains data (and ...
4
votes
0answers
125 views

I can't create/save changes in shape files on QGIS

I can't create or edit shapes in QGIS, the files are created on my system but cannot "fill" it with the features. I'm using QGIS 2.14.2 64bit Windows 7 This is the error i get when trying to save a ...
4
votes
0answers
35 views

Animate panning map in QGIS?

I want to create a short video illustrating the route of a proposed road by starting the map in one position, then panning to a number of other points. Is this possible in QGIS using the time manager ...
4
votes
0answers
26 views

How can I get a numerical (or value) display for equal intervals in a layer?

I'm looking to classify regions on a map by the amount of light pollution in the area. I have the varied intensities (0 through 60) plotted using a color map, but is there anyway that instead of a ...
4
votes
0answers
54 views

Issues updating field values programmatically for particular field data type on 64bit Windows computer using QGIS 2.8.7

I have an issue with a plugin for QGIS 2.8 I'm developing when using it on a Windows 64bit machine (as opposed to 32bit). I am trying to update values in a particular field in my plugin, and the ...
4
votes
0answers
92 views

Import Vector data to QGIS from pdf and apply georeference

I am Using QGIS 2.14. I have a pdf created by Mapinfo, it contains multiple layers of vector data that I can open as separate vector layers in qgis. However no map projection data was saved to the pdf....
4
votes
0answers
92 views

Which statistical methods to compare the spatial distribution of two different variables in two raster maps?

I am working with two global raster maps using the R Software (original file: netCDF for map 1 and GeoTIFF for map 2), with a resolution of 5 min of arc. Map 1 contains data on the share of the land ...
4
votes
0answers
41 views

QGIS canvas: I cannot remove blue “nested” grid/rectangles in canvas (BTW what is it?)

A blue "nested" grid suddenly appeared in the canvas (see image below). I don't know what I did to make this happen and how to get rid of it. Can anyone please advise me on how to remove this?
4
votes
0answers
51 views

TypeError: QgsEncodingFileDialog

I am using the latest version of QGIS (Lyon) on MAC and have set the default Python version 2.7. Moreover, I have installed all the required python modules and GDAL. It was working before, but now, ...
4
votes
0answers
37 views

Is it possible to have a locked TOC in QGIS

I would like to customize QGIS for a custom use case where the user will work with a very simple customized UI and will just digitize features in existing layers. Therefore the TOC should be locked, ...
4
votes
0answers
59 views

Insert sequential row and column values automatically into a fishnet dataset

I have a grid that has about 30 rows with approx 15 columns each. I want to label them as A1,A2,B1,B2 etc (Alphabet row, integer is column). Is there any way to do this programatically? There is no ...