Questions tagged [vector]

A coordinate-based data model that represents geographic features as points, lines, and polygons.

238 questions with no upvoted or accepted answers
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57 views

Referencing an output in an expression in process modeler

In the process modeler, I'd like to reference an output of a previous step as one of the parameters of an algorithm. In this case, the previous step was clipping a large raster and I want to use the ...
4
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2answers
365 views

Density map of pedestrian paths and footways in QGIS

I need to identify public places within pedestrian areas in London, so I need to calculate the density of both pedestrian links and footways. I have classified my data according to the categorization ...
4
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0answers
163 views

QGIS 2.18.14 vector Clip analysis producing erroneous result

I am trying to perform a vector clip analysis (vector-->geoprocessing tools pull-down menu) using two complicated vector layers and am getting erroneous results. The clip 'Input layer' is shown here: ...
4
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0answers
869 views

How to perform spatial join and obtain attribute in python/GDAL?

I am working on a script that will take an unprojected raster, and using a UTM grid (shapefile), will obtain the correct SRS (I have a shapefile where each zone is attributed with its numerical SRS) ...
4
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0answers
67 views

Qfield crashes when vector elements are touched

I have a problem with Qfield. I'm using qfield 0.8.8 on OS android 5.1.1 After having installed this Qfield version it does not run. When I touch a polygon or a line or a point it crashes; in ...
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0answers
44 views

How to restrict the creation of vectors (end vertices) to existing vertices in QGIS

My specific interest lies in network creation, however, knowing how to do that in general would be a plus. Is it possible to prevent a user from creating a line (line vector) without connecting it ...
4
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0answers
5k views

problem with saving to esri file

I was using Wroclaw 1.7/GDAL 1.9(earlier release)/Grass 6.4/GSL 1.15-2 and started getting the following message when saving any item to esri format. "Export to vector file failed. Error: creation of ...
3
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1answer
130 views

Splitting feature in OpenLayers 5?

How do you split an OpenLayers Vector Feature (Polygon or a LineString)? i.e ux: select feature, select a 'split' UI button, draw a split on-top of the polygon or through the line. The feature ...
3
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1answer
129 views

3-D Terrain effects for vectors in QGIS?

I'm a bit new to QGIS, and making a few maps of roads through mountains. I'm looking to have a 3-D effect within my 2-D map. I got a DEM, made a hillshade, and blended a basemap over it. Nice ...
3
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1answer
71 views

Fixing self-connect polygon in QGIS 3.2

I'm trying to clip a soil map layer and am getting invalid geometry that affects my clip result. The problem appears to be a self-intersecting polygon. I've tried using the 'check geometries', and ...
3
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0answers
65 views

Replacing Multiple Polygon Geometry

I am carrying out a piece of work in ArcGIS 10.4.1 that involves realigning polygons to an updated vector map. The polygons in question are planning permission boundaries that are created showing the ...
3
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0answers
709 views

How to get EPS vector as georeferenced layer into QGIS

I've got a eps-file with polygons of landuse. The file have got coordinates to georeference it. I need to convert it into a geo vector. I could do the following steps: export/convert the eps to ...
3
votes
1answer
477 views

Generating customized vector OSM map files from OpenStreetMamp and other data?

I am looking for a way (e.g. tutorial?) to generate my own customized (offline) maps in OSM format. By "customized" I mean adding data (not just define a region of interest) to an existing OSM map (e....
3
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0answers
154 views

How can I optimize performance for QGIS 2.14 vector processing?

I am attempting to do a Count points in polygon routine for a clean looking 'density' grid. I have around 800,000 points over a large polygon grid. My workstation has 24 cores and 128gb RAM, and yet ...
3
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0answers
2k views

QGIS “join attributes by location” fails

I am trying to join attributes from a vector polygon layer to a vector points layer wherever a point falls inside one of the polygons. I tried to use the QGIS 'join attributes by location" tool, ...
3
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0answers
160 views

How to accelerate v.generalize on massive vector data?

I have a big problem with my vector dataset (more than 1 million entities) and v.generalize in grass 7.0.5 and 6.4 (64 bits for both). I try to use Douglas method on this dataset but it is very very ...
3
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0answers
160 views

How to measure orthogonal distance of line from point in QGIS?

As I am fairly new to QGIS I'm seeking your help. I'm trying to measure the distance between points in a point Layer P and the end of lines in a line layer L. In L there are two categories (attributes)...
3
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0answers
82 views

Determining the first and last point that a polygon intersects

I have this... And I want to join those attributes to the polygon automatically: Because I'll have to replicate this on tones of those polygons. If this works I would like to know if it still works ...
3
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0answers
199 views

QGIS becomes unresponsive when adding new vector layers?

QGIS suddenly won't allow addition of new vector layers when running on PC (Lyon 2.12.1). I've reinstalled it, no help. I've recently changed to Windows 10 from 7, otherwise nothing much has changed ...
3
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0answers
241 views

Regridding vector values

I'm trying to regrid and interpolate vector values from WAM model output. I got WAM model netCDF output in rotated grid, I need to interpolate it to another grid which is some variant of LAEA ...
3
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0answers
243 views

PyQgis - Adding attributes to a POSTGIS layer

After reading @underdark's answer to this question on creating a new vector layer and @Matthias Kuhn's to this one on field calculation, I wrote a script that allows me to calcultate the mean arrival-...
3
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0answers
821 views

Intersecting vector data with raster data in PostGIS?

I have Open Street Map [OSM] data imported so that I can access the geometry of buildings. I have also loaded SRTM digital height data from NASA from a GeoTIFF raster. I have projected the raster into ...
3
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0answers
470 views

Cross-browser marker animation in OpenLayers

Currently I'm trying to implement animated markers in OpenLayers. I'm using PNGs for the markers, set by the externalGraphic style property on an OpenLayers.Layer.Vector. I need to be able to make ...
3
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0answers
559 views

How to render a transparent raster layer on top of one or more vector layers with PyQgis?

I been trying to render a map with a 3 vector layers and one raster layer. The idea is that the raster layer should be on top of the other 3 vector layers. The problem is that even when I add the ...
3
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0answers
174 views

Moving legend items up and down in QGIS

How can I change sort order in layer properties styles tab? The only way I've found is to change their labels and order by it.
2
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1answer
72 views

Calculate area with a buffer

I am looking for help for my master thesis. I have two layers, a set of households and burned area (vector data). I created buffer zones around each household and now want to estimate the burned area ...
2
votes
1answer
28 views

Erode islands of pixels while polygozing a raster

I am polygonizing a single band raster. I am using gdal.Polygonize() function to vectorize the raster. img= r"C:\Users\aoi2.tif" src_ds = gdal.Open(img) srcband = src_ds.GetRasterBand(1) # create ...
2
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0answers
27 views

Reprojecting a shapefile Error

I am trying to write a function to reproject a vector file , by taking the original shapefile as input and giving out the name of the reprojected layer . Though when I call this function I get an ...
2
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0answers
49 views

Spatial distribution of vector polygons

I have two vector layers and I am looking for a tool for spatial distribution of the polygons. polygon 1 is the frame, polygon 2 are objects with different size and distribution. I need an index value ...
2
votes
1answer
117 views

Coordinates of an area on a raster in QGIS

I am new to GIS and I have to do the following: I have a GeoTIFF raster file of a map with some features like clouds and water bodies. It is a satellite image. My images are taken from a snapshot of ...
2
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0answers
25 views

Query of line direction histogram plugin

I was wondering if anyone could explain how this plugin works I have had a play around with it and I do like how it visualizes how vectors are orientated. However I ran one and opened the CSV file ...
2
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0answers
27 views

How to delete a file after processing an algorithm in QGIS 2.18?

I am trying to delete an intermediate file ("Temp_merged.shp") after running the singleparts to multiparts algorithm in QGIS 2.18. import glob, os, processing path_to_shp = "C:/Temp/Tracks/" ...
2
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0answers
80 views

Vector map (rivers) to Raster. [ **ERROR 1: Wrong value for -outsize parameter.**]

I want to transform this vector map: To something like this I only tried to convert the vector map through Raster> Conversion> Rasterize But I get this Error: QGIS version: 3.6.3-Noosa QGIS code ...
2
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0answers
46 views

Isolating main polyline using QGIS?

I am trying to convert a line shapefile with branches into just one polyline, actually deleting every other diramation. Imagine something like this: :________|__________|____|||______ into :...
2
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0answers
730 views

Error in reproject vector file using GeoPandas

I have a vector file (in this case shp file) and I read it with GeoPandas (gpd). vector_folder = r'C:\poly' vector_file = 'poly.shp' df = gpd.read_file(os.path.join(vector_folder,vector_file)) df ...
2
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0answers
66 views

How to export a single feature (line) from multiple layers and export to individual layers?

I have multiple vector layers representing a time series. Each layer contains many lines each. I want to select a single specific line from each of these these layers and save it to another layer. ...
2
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0answers
33 views

Issue with vector grid and calculating area QGIS

I'm trying to determine the area of occurence from a large polygon superimposed onto 2km x 2km grids. The goal is to have a slightly coarser answer then a straight area of the original polygon as the ...
2
votes
2answers
843 views

Changing vector extent in QGIS

I've been looking for a manner to change a vector extent in QGIS, but it's unsuccessfull! I want change extent because in the past, I had problems to convert vector to raster. I try present the ...
2
votes
0answers
62 views

How to sum attributes from different vector grids?

I am using QGIS and have a vector grid covering part of South Europe. The grid is made of rectangles each with equal size 0.01 degree. So there are thousands of features defined by four values : left, ...
2
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0answers
71 views

Saving vector layer into KML across 180 longitude line

I am trying to save a vector layer into KML, however in this case some of the shape cross the 180 longitude line and the shape just breaks and become long lines.. (they are supposed to be circles) ...
2
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0answers
139 views

Shape index, compactness and assymetry index with PostgreSQL /PostGIS

I am working on automated land parcel identification and would like to extract road/river/thin and linear-like polygons from a massive dataset. For now, the only index I can get some answers from is ...
2
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0answers
233 views

Create 3D polygon from 3D point map

I'm a new qGis user (just started yesterday) and I'm trying to find a solution to a problem. I need to generate a 3D polygon starting from a list of points located in space, with X and Y coordinates ...
2
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0answers
187 views

How to merge large number of vector features with QGIS SingleToMultipart?

My goal: Merging all line segments in a vector to a single feature. My approach: QGIS module singlepartstomultipart My problem: For larger numbers of features within the line vector, the module ...
2
votes
0answers
156 views

Openlayers3, vector data layer not visible after proceeding select onchange function

I input two polygon geojson layers, one is just boundary layer, another is the vectorlayer contains many attributes. I add map.on('click', function(evt), so users can click on the map, and the ...
2
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0answers
93 views

Create A Maximum-Gradient Vector Overlay QGIS

I have generated several vector layers of different gradients and geographic areas (PUMAs, ZCTAs & Census Tracts). Is there a way I can overlay all these layers with the aim of identifying the ...
2
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0answers
576 views

Problem merging polygons in QGIS

I've got a polygon shapefile with 11 features (11 Italian cities) and I want them to merge them into one, however I cannot activate the "Merge selected features" button. Any suggestion about the ...
2
votes
0answers
989 views

Create map (image) from raster and vector in Python - problem with big files

I wrote function which allows me to plot raster and (optionally) plot vector on the same image. It works for small files, but in case of big rasters, I receive memmory error. I've tried to add ...
2
votes
0answers
316 views

Automate Running Shortest Path

I have to use a qgis method (python, plugin, scripts) only to automate a shortest path calculation for multiple start and end points. How might i automate the shortest path road graph tool?
2
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0answers
201 views

Converting vector layer to raster with cell size same as other raster using QGIS?

I am a student and was taught by my professor in ArcMap but he wants us to repeat the process in QGIS. And i dont know how to set cell size in rasterize (vector to raster)in QGIS just like in ArcMap. ...
2
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0answers
322 views

QGIS SegY Compatibility

I am currently having a problem importing SegY files into QGIS. Following the 2.14 update, SegY compatibility should be available to bring in the navigation stored within the file as a vector layer. ...