Questions tagged [vector]

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

226 questions with no upvoted or accepted answers
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414 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 ...
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81 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 ...
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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I just updated my very outdated version of QGIS.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 ...
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131 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 ...
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198 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 ...
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105 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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229 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 ...
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604 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 ...
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856 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 ...
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266 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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67 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 ...
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69 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 ...
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325 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 ...
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175 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 ...
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672 views

What C/C++ libraries exist to transform vectors between map projections

Has anybody written a C/C++ library (preferably one that is aware of Proj.4 definition strings) that has a set of routines to convert vector quantities (e.g., wind speed and direction) between map ...
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971 views

Loading Vector Layer PyQGIS Issues

I am trying to follow PYQGIS documentation for loading a shapefile from inside a script. http://www.qgis.org/pyqgis-cookbook/intro.html I was able to set the datasource and run the QgsVectorLayer ...
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173 views

Can I edit WMS layer or KML layer?

I am using OpenLayers and until now I have been using OSM as background and I got points from my database (mySQL) and added them to vector layer, then I could modify them and save it back to the ...
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238 views

Base station coverage analysis in QGIS

I want to find base station coverage for a instant location. I have building data. And i determine optimum coverage as 500m far away from a base station (buffer). So how can i find optimum base ...
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899 views

popular solution for display both tiles and vector data in android map app

We are planning to build a location based app like google map in android. We have some experiences in the PC development,that's to say we have a similar javascript api like google map javascript api, ...
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913 views

how to search a vector/wfs layer

I'm using Geoserver/PostGIS/openLayers I've succesfully set a vector layer. And now I'm trying to create a search functionality. But something goes wrong. First I set up the layer and add some basic ...
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326 views

Overlay Shapefile onto Geotiff

I have a Geotiff map and I want to overlay a Shapefile onto it. Ideally I want to specify a 'nice' style for the polygons e.g. have them opaque (for now all polygons should be the same). I want to ...
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808 views

Creating a sidewalk map for a walkability survey

If I wanted to do my own walkability survey of my city, what tools could I use? I have map data from OpenStreetMap, but I have to consider that streets have two sides (which aren't always accessible ...
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1answer
32 views

QGIS Raster to Vector Conversion - 3.4.6-Madeira

I have some contour lines in raster format, I want to convert them vector. I tried with QGIS (version 3.4.6) I got the vector form. But when I tried to select the contour lines to put the actual ...
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1answer
25 views

Selecting a polygon area in a raster image - rasterio.mask vs roipoly

How should I select a polygon area in a raster image? So far, I have seen two methods: use a vector mask or a shapefile (some examples here: http://www2.geog.ucl.ac.uk/~plewis/geogg122-2011-12/...
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16 views

Running v.net.steiner in segments?

I am using GRASS GIS 7.6 on a CentOS server with 157 GB of RAM. The vector categories of the network layer that I need to run the Steiner tree algorithm on are as follows: Layer/table: 1/network type ...
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14 views

Interactive tool for editing TIN data

I created TIN to generate DTM using Mass points from Lidar data and river data that I made from stereoplotting. TIN results show there are several locations where the river elevation floats. So I have ...
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40 views

QGIS freezes when trying to view layer properties

As of recently whenever I try to edit the properties of a vector layer the entire program just freezes and I'm forced to end the process using task manager. I use Windows 10. Any reasons as to why ...
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33 views

QGIS: Polygonize error

Running the Polygonize tool in QGIS keeps generating the following error: Processing algorithm… Algorithm 'Polygonize (raster to vector)' starting… Input parameters: { 'BAND' : 1, '...
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1answer
38 views

Polygonize specific raster values QGIS

I have a raster of 36 classes of the land cover in South Africa. However, I only need 4 of these classes and create a polygon out of these 4 classes combined. I have now used the raster calculator to ...
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16 views

Calculating the distance of raster cells from a vector within a polygon using QGIS

I am quite new to QGIS and am trying to use QGIS 3.6 to create a raster layer of calculated values of the minimum distance of each cells within a polygon (orange) from a vector (the river channel in ...
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19 views

Can QGIS be used to calculate the up-slopes (total area draining to a specified point) of multiple separate points simultaneously?

I am trying to calculate the area draining to a point of 240 separate points using QGIS. At the moment I'm using the Saga - Upslope Area algorithm to individually work this out for each of the 240 ...
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1answer
72 views

Automatic correction of many topological errors in shapefile?

I have a database with topological error. In particular I have an overlay of polygons. I would like to correct these errors. I thought to use an automatic procedure since I have a lot of errors. I ...
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38 views

Vector tile generation

I have a full planet imported in PostgreSQL with imposm3. What is the best way to generate vector tiles (MVT in .mbtiles) from PBF/PostgreSQL with maximum hardware utilization (distributed generation ...
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1answer
48 views

Python: Convert shapefile to GeoJSON whilst stripping and renaming fields

I'm writing a Python script to convert shapefiles into GeoJSONs but I would like to remove many of the fields as they are redundant and rename the ones I am retaining. Here's an extract of where I ...
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1answer
47 views

Calculating areas of polygons that match with overlapping raster threshold value?

I have a polygon of districts (districts.shp) and a raster of rainfall (rainfall.tiff). I want to calculate the area of each district that saw rainfall greater than various numbers. I'd like to ...
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73 views

Fixed distance buffer is oval in QGIS?

I want to create circles of diameter 20m in QGIS. I create a point and then use vector - geoprocessing tools - fixed distance buffer. My problem is that the size is crazy and worse, the shape is not a ...
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129 views

PyQGIS raster image shifted from vector shapefile

I previously asked a question about my raster image being larger and shifted over from my vector image here, but now I realize that the raster image is only shifted to the left and up from the vector ...
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45 views

Storing a large amount of vector layers on PostGIS

I'm developing a web application where PostGIS will be used as a vector tile server backend to serve mvt tiles. For each user of the application at least one vector layer will be created. So, ...
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85 views

Can relation reference in QGIS and QField be used to fill stochastic matrices?

I am a novice GIS user and am just seeing the potential for relations in my work. A problem I've come across and would like a solution to it. I have two stochastic matrices (risk matrices) that ...
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39 views

QGIS 3.4 (mac) std::bad_alloc error

I get the above error when trying to add a new raster or vector layer. Does anyone know how to correct it as the resulting projection is nowhere near where I need it.
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416 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 ...
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199 views

Does any version of QGIS support GDB 10.5?

Does any version of QGIS support GDB 10.5? I have a GDB 10.5 file that I need to open in QGIS and I can't. I'm using QGIS 3.6. The file is named Virginia_Parcel_Dataset_2018Q4.gdb -- it can be ...
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168 views

Vector Rasterize Error

I am running QGIS 3.4.4 With GRASS 7.4.4 and I get an error while rasterizing a vector layer and I don't know why. The same error pops up while using GDAL->Rasterize(vector to raster) and while using ...
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28 views

Vector to grid - Computing statistics by grid cells

I have a vector point data from drifting buoys (speed, direction, sst, slp) that I want to analyse in a grid. What are the right tools for this? Example of my points data below. Each point has the ...
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63 views

Raster values shows no data when using identify features tool

I used vector to raster function in QGIS, to convert some points with different values to raster. I tried to use the "Identify Features" to check values for each raster box. The values shows no data ...
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87 views

QGIS fails to generate requested number of random points

Does anyone have any ideas what might be blocking this process? The layer has thousands of polygons totalling hundreds of thousands of square metres, but when asked to locate 140 random points even ...
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64 views

How can I calculate the “average” or “median” result between a number of MultiLine Strings?

So I have a number (let's say 12) of multiline strings representing something that changes over time, like forest borders or shorelines. I want to create a single line that is the result of the ...
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46 views

QGIS vectors and rasters

I have created a map with polygon shapefiles and am trying to import them onto an different raster but when I do they are larger than the raster image and are far away. What am I doing wrong? My ...
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43 views

In ArcMap, how to create random points of a specific amount in each polygon?

I am doing an accuracy assessment of land-use product and need random points as test points. What I'm trying to do is to generate different numbers of random points in different polygons (like 5 for ...
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39 views

How could I assess the value of a polygon according to the value of his neighbor?

I would like to know if it is possible to give a value to a polygon, according to the value of the polygons around. I want to assess the ecological integrity of an aquatic network (lakes, pond, ...