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Questions tagged [vector]

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

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133 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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57 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
121 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 ...
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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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0answers
464 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) ...
3
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0answers
97 views

When moving a feature in QGIS, is there a way to nudge it rather than use the mouse?

I need to move a lot of features (polygons) in QGIS to fit a newly Georeferenced scanned map that is slightly asymmetrically distorted. This is fine as it is just to provide a print copy. I end up ...
3
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0answers
125 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
1k 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, ...
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42 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 ...
3
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0answers
78 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
31 views

Snapping vectors to vertices for ROI delineation?

I am trying to manually extract a set of ROIs in ENVI 5.0. However, I can't seem to successfully line up the vector to be flush with the boundary of the pixels, which means I don't have fine-tune ...
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0answers
150 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 ...
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173 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
216 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-...
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0answers
725 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
427 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
529 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 ...
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0answers
149 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.
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0answers
31 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 ...
2
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0answers
22 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
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0answers
45 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, ...
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0answers
43 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) ...
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0answers
81 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
274 views

Aligning raster data to vector data in QGIS?

I'm in the midst of aligning century-old maps (of Paris) to vector data of the modern same: Qgis' Georeferencer tool works fine, but doing the entire city that way is a gargantuan task. Paris hasn't ...
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0answers
138 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
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0answers
126 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 ...
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0answers
75 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
votes
0answers
355 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
665 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
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0answers
240 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
votes
0answers
143 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. ...
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0answers
117 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)...
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0answers
121 views

Open raster and vector files with PyQGIS

I'm making a plugin for QGIS and I'm trying to open the layers I've created on QGIS, but I only get to open the one called 'sinkhole raster' which is the input of the tool. I don't know what order ...
2
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0answers
67 views

Finding vectors with wrong direction in river network

I have a shapefile containing network of rivers for the whole country. The description of the layer is saying that orientation of the vector should be the same as the river flow. This is true for most ...
2
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0answers
153 views

QGIS Lost precision when converting raster to vector

I am after running ordinary kriging, converting raster to vector I lose decimal value and only get whole number. I have added first the raster then the vector image.
2
votes
0answers
59 views

Trigger event after KML Layer completely loaded

I want to set the bounds of my map after a Vector (KML) Layer is loaded. kmllayer.events.register('refresh', kmllayer, function(evt) { map.zoomToExtent(kmllayer.getDataExtent()); }); In the ...
2
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0answers
294 views

Command line join attributes by location using OGR

I have two overlapping vector files (polygons and sample) and want to do a spatial join from the command line to extract all features in polygons that intersect with sample. Essentially I want to have ...
2
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0answers
75 views

Converting u and v from WGS84 to NZTM2000 - Do I need to do vector conversion?

I have u and v wind component values in latitude and longitude in WGS84. I want to convert this to NZTM2000. I've converted the lat/lon in ArcView - (and will try in R) - but do I need to also do some ...
2
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0answers
27 views

QGIS upgrade from 1.8 to 2.12: Vector layers are not displayed

I just updated my very outdated version of QGIS. I was running 1.8 and thought the new version would work out a couple kinks that had developed. Well, now I can't even figure out how to make my vector ...
2
votes
0answers
130 views

QGIS 2.12 map composer issue with vectors

I am making a map that includes all kinds of vector layers; the map looks perfect in QGIS 2.12 Lyon as well as in map composer. None of the layers have scale-dependent visibility. I have the ...
2
votes
0answers
90 views

How can I measure the distance between many polygon features and either another polygon or a line in QGIS?

I often have to manually measure the distance between a single site and other sites around it, but obviously this can get long-winded and I feel like there must be a much more efficient way of doing ...
2
votes
0answers
92 views

Error trying to save vectorfile in QGIS 2.10?

I'm trying to save some changes I made in a vector file (polygons) in QGIS 2.10. The file contains properties and I want to merge two of them into one. I toggled and selected the two and then pressed ...
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votes
0answers
201 views

Creating a 3D model of airspace that I can interrogate to see if some other feature (like a tree) will intrude into the airspace

The goal is to create a 3D model of imaginary planes in space that I can interrogate to see where other objects in the vicinity of the model cut through any part of that plane. For example, an ...
2
votes
0answers
487 views

How to make a model with more than 2 input layers for buffering and merging?

Would it be possible to add more inputs to Buffer and Merge? From what I can see there is a limit of two input layers per both. As far as I know this is possible in ArcGIS's Model Builder but from the ...
2
votes
0answers
756 views

Merge multiple geojson-polygons

Lets say I have a very big image With a polygon in it: I want to polygonize this very big image with gdal polygonize. But the image is too big, so I dont have enough memory to polygonize that ...
2
votes
0answers
238 views

Connect two contour lines with calculated line length

Is it possible to make a plugin for QGIS like PEGGER for arcview 3.2? Problem is, how to make path over contour lines with a gradient in percent? Formula is: K= e*100/G*M ; K=10*100/0.08*10000=1.25m ...
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0answers
64 views

Aggregate nearby points to develop equally sized regions in QGIS

I have a list of 4,500 points (lat, long, unique id, attribute). I also have a service territory which all of the points fall into. I would like to break the service territory (polygon) into 6 ...
2
votes
0answers
66 views

QGIS polygon areas inside a polygon

I'm having hard time doing the following analysis in QGIS: I have watershed polygons with individual IDs. Then I have four different shape files, each having different land use polygons. I would ...
2
votes
0answers
315 views

Update Attribute based on spatial location

I want to spatially (Spatial Join) update few fields, not all, from another feature class. Is there any way to select and update few fields instead of all the fields from the other layer and ...
2
votes
0answers
164 views

Adding feature to GeoServer vector layer using WFS-T in absence of fid index?

I want to add a feature to GeoServer vector layer with WFS-T. When I use saveStrategy.save(), an error returned that said: java.io.IOException: current fid index is null, next must be called ...