Questions tagged [qgis]

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

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109 views

Sort selected points by latitude/northing with field calculator

I have bathimetry data in .shp format. The points (picture below shows one of multiple groups/profiles) do not have ID numbers and are randomly dispersed through the attribute table. I have selected ...
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1answer
116 views

Possible to convert v.net.spanningtree to QGIS custom script so don't need GRASS installed?

Is it possible (and if yes then how or has this been done) to convert v.net.spanningtree in to a QGIS/python (custom) script that can be accessed in the QGIS graphical modeler in a way that GRASS is ...
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1answer
1k views

Bluetooth my GPS signal to windows 10 tablet using QGIS

Could anyone tell me how they pair their mobile phone gps to a (windows 10) tablet that can be picked up by qgis live tracking? I have tried a few apps which i believe is broadcasting the gps to my ...
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2answers
201 views

How to open a layer in QGIS from another application?

Let's say I have some metadata about a layer stored in some custom application, and I would like to open or view the layer in QGIS. What, if any, are my options? Edit: formats include shp, wms, ...
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1answer
214 views

Getting information from one shapefile to another using QGIS

I am very new to GIS and learning by myself. I am using QGIS. I have a shapefile, which categorizes areas (land cover) by numbers (corresponding to land cover classes). I have created a wkt file ...
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1answer
414 views

QGIS WCS client with clip parameter

Can be defined bbox parameter in a WCS service? I require trimming the layer coordinate in a box, I'm trying to prove the following WCS, but shows the entire layer globally: http://geobrain.laits.gmu....
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20 views

Kernel Density Estimation Weighting Factor

I dont understand where is this weighting factor coming from, does it need to be in the quakeLyr in the attribute table named with "mag" or? ##Now, we can run the kernel density estimation algorithm ...
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1answer
931 views

Nearest neighbor analysis not showing results

I'm trying to do a nearest neighbour analysis on fish shoals distribution. I go to Vector > Analysis Tools > Nearest neighbour analysis. I choose the appropriate layer and when I hit ok the black ...
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1answer
61 views

Unable to resize polygons/lines imported from Google Earth PRO Using KML Tools

I imported all my files from Google Earth Pro into QGIS and I need to resize some of the polygons (after agricultural job is done, some of fields get bigger or smaller; from corn we go to soy etc.) ...
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1answer
2k views

How to install Sextante in QGIS 1.8 without Plugin Installer?

How can I install sextante (and where can I download it) if the Plugin Installer doesn't works? As I work for a corporation, I have some problems conecting to the official repository, and I cannot ...
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213 views

Connect to local file or PostGIS layer in field calculator QGIS

I'm trying to make query from field calculator so that it would be possible to connect to PostGIS layer (or local file on computer) and select data according to condition so that use this selection ...
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164 views

Delayed moving average

I want to develop a plot of delayed moving average. The code for this in MATLAB is: nr_pontos = 36; coefs_filtro = ones(1, nr_pontos)/nr_pontos; data_dma = filter(coefs_filtro, 1, data); figure,plot(...
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1k views

QGIS OpenLayers plugin needs to be reloaded

Using QGIS 2.12, I successfully add basemaps via Web > OpenLayers plugin. However, if I save the project (EPSG:3857) and later reopen it, the OpenLayers basemap will not display. As a workaround, ...
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1answer
64 views

Using fixed QGIS modeler vector input parameter?

I'm writing a QGIS (v3) model and I'd like to have a vector layer input fixed to a specific shapefile. This way, every time I run the model, I don't need to select the file. Is this possible? Right ...
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4answers
842 views

Buffer in QGIS/R is 650-670 m wide instead of 500 m

I am trying to make a 500 m buffer for my polyline layer. Unexpectedly, I receive buffer varying from 650 to 670 m, depending on location. As many resources recommend to use UTM before making a buffer,...
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1answer
2k views

QGIS and MapInfo Projections - EPSG 27700 (British National Grid)

I have some data in a PostGIS table with the projection EPSG 27700. If I export this data from QGIS (v1.8) to MapInfo TAB / MIF when I open the data in MapInfo it has a shift on it. Does anyone know ...
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752 views

QGIS window size problem [duplicate]

I just installed QGIS 3.2 on a new laptop and the map canvas window and map composer windows are half the normal size, with a grey background making up the remainder of the space. How do I make the ...
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1answer
2k views

Performing weighted sum overlay analysis in QGIS?

I have weighted raster data converted from polygons with different categories. I have ArcGIS with 3D Analyst extension, unfortunately do not have Spatial Analyst, and I would like to use QGIS to ...
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1answer
786 views

Gdal_sieve not working with QGIS?

I'm using the Sieve command within QGIS (Raster > Analysis > Sieve), but when I run the command with any variation of parameters, it completely changes the histogram of my raster data from between -0....
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2answers
3k views

Extract Elevation of Points from DEM using Python QGIS or GRASS

I am utterly new to GIS, so please bear with me if I am providing incomplete information here. I have a DEM file (.dt2). What I am looking to do is as follows: take a series of points specified as ...
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1answer
4k views

Is it possible to load an .las file directly into QGIS? [duplicate]

Is it possible to load an .las file directly into QGIS? I would like to be able to load LiDAR data and to be able to do analysis based various feature attributes; e.g., elevation, classifications, ...
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1answer
1k views

Retrieving lost data from QGIS? [closed]

I'm trying to help a friend retrieving QGIS data from a formatted drive. Finding the .qgs project that was saved on the desktop is no problem, but it seems that there is no actual data located in ...
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26 views

Getting duplicate values when joining .csv spreadsheet to .shp map layer using QGIS?

I need to join .csv/spreadsheet data to the .shp map layer. The join itself isn't a problem with same join & target values (building) but some data goes missing because of duplicate values. For ...
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0answers
25 views

Get value from point layer based on start/end of line layer [duplicate]

I need to get a value from a point table based on the end/start point of a line. This is similar to my question QGIS Field Calculator Aggregation with a intersect query aggregate( layer:= 'Point_Clip'...
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1answer
235 views

Sorting grid cells in fishnet grid by location and number using QGIS?

I am using QGIS 3.2.0 on a Mac (and also have QGIS 2), and I have a fishnet grid (probably created in Arc) that comprises of nearly 2 million grid cells. As a result, every change I make to the ...
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1answer
155 views

Is there a way in QGIS to cluster rather than overlap SVG icons from all layers

I have many layers in QGIS containing points. All layers were added as delimited/csv. PROBLEM: These are points from different layers, I'd like them clustered around the area instead:
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2answers
312 views

where is the v.transects algorithm in qgis?

I am interested in using the v.transects GRASS command. I am however not yet proficient with using GRASS or python in QGIS environment so I would rather do it the old-fashioned way (i.e using the GUI)....
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2answers
124 views

shapefile terminology for key-value pair

In an .osm file, there are <TAG ... /> elements like <way visible="true" id="-4409" timestamp="1970-01-01T00:00:00Z" version="1"> <nd ref="-21845"/> <tag k="fcc" ...
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2answers
266 views

Manually add a new point to PostGIS table [duplicate]

I did accidently delete a table row - or well, in fact a whole subway station. My attempt to solve the problem was this PostGIS function: ST_GeomFromText('POINT(coordinates)') But then PostgreSQL ...
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0answers
273 views

Memory issue? qgis python processing does not complete

I have a simple process to make some edits to all the contour files in a directory. It runs fine on the test of 100 odd files but in a directory with about 500 it stops after about 120 files. Is ...
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0answers
268 views

What happened with NVIZ?

I'm unable to find and run NVIZ and now I've read several places that it's not functioning in the latest versions of QGIS? Is this a temporarily bug or definite?
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0answers
37 views

Does QGIS support true circular curves? [duplicate]

As a land surveyor, I often bring cad data into a GIS and create polygon representing parcels. Traditional tools I have for cleaning topology are inappropriate so I am looking for something different ...
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1answer
309 views

How to find the path after “cannot find module” message when I try to use grass tools in qgis [closed]

I use mac and when I try to use grass modules in qgis (brighton) I get a "cannot find module" message.
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1answer
3k views

Replacement of QVariant and setAttributeMap in PyQGIS

I am updating a plugin for QGIS 1.8 to QGIS 2.x. I have the code below. The setAttributeMap does not exist anymore. I have replaced it with fet.setAttributes and it seems to work. When using fet....
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0answers
148 views

How do I join multiple features with a single geometry-less table entry? [duplicate]

I have three features with the same ID, let's say "5". I also have a corresponding text table containing IDs among other info (for example a "category" value). I want to join the table with the ...
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1answer
568 views

How to automatically convert line features into polygons using QGIS/PostGIS?

I have a master table of line features and a number of tables that I use to join (in the SQL sense) to produce various layers. Some of theses layers consist of boundaries of administrative zones (...
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1answer
219 views

Zonal statistics results in some NULL values in QGIS?

I used zonal statistics through QGIS to assign raster image values to polygons. Here, Raster image has value in range from 0 to 238.567. As a result, some NULL values are assigned to polygons, even ...
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1answer
69 views

How to give a table some geometry from a view on QGIS using a join?

So basically I've got this static table that people update information Then I need it to give it some geometry from a view table. This geometry is dynamic, that's why can't just make a new geom ...
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1answer
452 views

Installing Lizmap with PostgreSQL

I've been trying to install the Lizmap webclient. I was following this guide. I've successfully came to the part where I have to set up my config files. I am suspecting the error lies within my ...
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1answer
655 views

Replacing PyQt4 with PySide with standalone QGIS

I would like to develop an application using the QGIS libraries and PySide instead of PyQt4 due to more flexible licencing, I wonder if this is possible. I downloaded PySide and replaced my ...
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0answers
223 views

How to export training area information?

I did a supervised classification of a whole Landsat 8 image with 700 Rois (training areas) with the Semi Automatic Classification Plugin. I want to export the class names, the coordinates and the ...
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2answers
2k views

QGIS crashes by opening project

Suddenly I got a problem opening the project I was working on since a long time. When I open the project, QGIS crashes. I think the problem might be in one layer, but as I cannot open the project I ...
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1answer
75 views

Batch travel distance calculation in QGIS

How to calculate the walking distance between postcodes and destination in QGIS? I have the following shapefiles: 1 layer containing the destination; 1 layer containing 1,000 postcodes. I've ...
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1answer
55 views

QGIS Line Subdivide by distance

I know in QGIS you can subdivide a line, but is there a way you can type in a distance and the line will split according to this, with the last segment being smaller in length? If not I will try to ...
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1answer
469 views

QGIS how to delete virtual fields?

I can't find the option to delete a virtual field on a layer, not even in the table manager plugin. Where is that option?
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1answer
245 views

Reclassify and combine rasters in QGIS?

I have a vector layer containing watercourse location which I have rasterized. I also have a DEM containing elevation data for the region in which the watercourses are located. I would like to ...
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1answer
3k views

Transform Shapefile from WGS84 to NAD83 using QGIS? [duplicate]

Possible Duplicate: How to reproject a vector layer in QGIS? I have some shapefiles whose CRS is WGS 1984 and I have some shapefiles whose CRS is NAD 1983 State Plane Illinois East. I want them ...
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1answer
862 views

Replacing values in multiple columns using QGIS Field Calculator?

In QGIS I want to search for a specific case and if this is true then replace the text in multiple columns. Based on Use updatcursor to replace values in multiple fields, Update multiple fields/...
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1answer
176 views

Is there a QGIS plugin that can transform tabular data to graph?

I have a CSV file with water level measurments in a well, taken once a year for 40 years. Is there a way to show this data as a graph (x axis being the date and y axis the water level) in QGIS?
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2answers
228 views

Spatial join geotagged images to preexisting point shapefile? [closed]

I have a layer of geotagged images (points with jpg thumbnail attachment), and another layer of different points (shapefile with various attributes). I would like to perform a spatial operation in ...