Questions tagged [vector]

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

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8k views

How to clear attribute columns from a Shapefile?

I want to clear all columns from a SHP. Only need geometry of features. I use QGIS and Sextante with grass and saga. Is there any tool for this job...
5
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2answers
820 views

Splitting vector file by date (year) but column containing dates in Day/Month/Year format?

I am using national accident data in QGIS and quite frankly the dataset is huge as it contains every recorded accident between 2005 and 2014. I've split datasets by field for a number of vector layers....
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2answers
825 views

Problem overlapping shapefile and raster in R?

I want to plot a shapefile over a raster file in R but I can't make them overlap perfectly: the raster appears to be rotated of few degrees counter-clockwise. Is it a problem with the projection? ...
5
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2answers
2k views

Spatial query of raster data using QGIS

I have population distribution data as a raster layer and exposure contours as vector (polygon) layers. What I'd like to do is use the vector layer to estimate the population indicated from the raster ...
5
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1answer
1k views

QGIS Calculate angle between two lines

I am currently trying to calculate the angle between two lines or rather vectors (which are not touching) like in the picture shown below: In order to calculate the angle α, I think I will have to ...
5
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2answers
1k views

Convert vector point data (shp) to raster (tif) using QGIS

Overall Question: How can I get the rendered tif image to keep the modifications seen in the image produced by map canvas? I am writing a standalone Python script. I have simplified my code below ...
5
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1answer
5k views

Change vector projection in Openlayers

I have added vector layer to map: vactorTest = new OpenLayers.Layer.Vector("Editable Features", { strategies: [new OpenLayers.Strategy.BBOX(), saveStrategy], projection: new OpenLayers.Projection(...
5
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2answers
833 views

Merging vectors 'global name 'dataobjects' is not defined'

I'm trying to merge contour line shapefiles but I keep encountering errors when doing so. I'm using Vector > Data Management Tools > Merge and selecting all six line shapefiles and given the ...
5
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1answer
27k views

How to plot certain values of a column in R?

Lets say we have a shapefile of cities with a column called category cities@data category A B A C A A B C How can i plot the A category only etc? Tried c<-cities$category[A] plot(...
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2answers
2k views

Overlay Vector Layer on Raster Layer

How can I overlay a Vector Layer on a Raster Layer and assign NoData Values on the Raster where the Vector Layer does not cover the Raster Layer? (preferable with ArcGIS)
5
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1answer
10k views

How to convert shapefile to vector EMF?

I want to convert a shapefile to an EMF file. The EMF file must be a vector image, not a raster image. Please suggest to me some good packages or tools.
5
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1answer
7k views

Showing menu based on right click on point geometry in JavaScript

I have implemented a vector layer(using JavaScript) in OpenLayers which has a point geometry. Now my requirement is to show menu just beside the point whenever we do right-click on the point. Can we ...
5
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2answers
2k views

Seeking QGIS affine equation?

I am at the mercy of a govt authority who have provided utility information in a cad format with a 0,0 origin and a nonsense grid. About a dozen files, the grid and origin are entirely arbitrary. To ...
5
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2answers
149 views

Splitting polygon using another polygon in QGIS?

I have two polygon layers (yellow and orange in the attached image). I am wondering if there is a way to get a count of the number of isolated areas that the orange polygon has divided the yellow ...
5
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2answers
224 views

Splitting polygons with single shared vertex?

I am trying to use QGIS to split a set of polygons into single parts where there is a join at a single vertex. The image shows a number of examples. I have taken a single polygon and used '...
5
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2answers
11k views

How to edit an existing layer using leaflet?

I am used to working with OL3 and I wanted to try using leaflet and see if it is as powerful as OL. I loaded a map with some data from a GeoServer WFS layer using this tutorial from Georepublic. var ...
5
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1answer
513 views

How to suppress polygon boundaries shared by objects of same type in QGIS?

Given polygons - like landcover in OpenStreetMap or street areas in cadastre - how can one suppress those polygon boundaries which are shared by objects (features) of same type in QGIS (see figure ...
5
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1answer
6k views

OpenLayers 3 displaying a vector layer

I have GeoJSON that happily displays on GeoJson.IO that I am trying to display on a vector layer in an OpenLayers 3 map. The GeoJSON is in EPSG:4326, the map is in EPSG:3857. My code is: view = new ...
5
votes
1answer
828 views

How to horizontally align irregularly shaped point symbol to vector layer in QGIS?

Fairly new to QGIS and searching a method to graphically align my point symbols in the direction of the vector. The symbol represents a water valve in an irregular shape in close proximity to a vector ...
5
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2answers
965 views

Distribute points respect to features using Quantum Gis

I want to know if there is any tool to make points with respect to selected features in a theme? Using: vector, investigating tools, regular points you can do it but not with respect to a selected ...
5
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1answer
660 views

Calculating shortest distance between multiple Polygon borders to a common Polygon border?

I have 2 sets of Polygons and I need to calculate the shortest distance between the polygons on one layer to the single polygon (one feature) on the other layer! How can I do that? Any help on how to ...
5
votes
1answer
548 views

Why is QGIS points in polygon so slow when select is fast?

I'm looking at QGIS 2.18.9 and using a polygon to select points from a large point layer (file based tab file). I wondered why the process is so slow if you use plugins or analysis options? I ask ...
5
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1answer
592 views

How to split a circle in equal parts in QGIS?

I'm looking to split a circle polygon generated by a buffer around a point in equal parts. The goal is to be able to calculate statistics about the raster that will be under the circle for each part ...
5
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1answer
201 views

Why is QGIS only one label rendering at a time?

I'm new to QGIS, but I'm experiencing what I think is a bug. When I load the qgis_sample_data landcover raster and lakes vector layers, then enable labels for NAMES on that layer, I can only ever ...
5
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3answers
316 views

Time delta between consecutive points of GPX file?

I'm in a course learning about GIS systems, and we have recently recorded a GPS track. I've exported this track as .gpx and imported the points into QGIS. Each point has a timestamp. One of the ...
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2answers
1k views

Is it possible to generate a vector polygon from a polygon on a raster image?

I have a raster map which I have extracted from a government report providing flood extent return frequencies. I want to 'snatch' these flood extent polygons (i.e. convert to vector) and I was ...
5
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2answers
243 views

Vectorize cell boundaries in GRASS

I need to vectorize the cell boundaries of a raster map and I have forgotten how to do this. For instance, if I have a raster map of a region that is just map=1 with a cell size of 500m, I would ...
5
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3answers
2k views

QGIS split vector layer gives me GPKG files but I need shp files

QGIS 3.6.0 I am new to QGIS software and not very technical on its deep workings. I am trying to split a .shp file using split vector layer. I need .shp file outputs but it auto creates .gpkg files. ...
5
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2answers
128 views

Creating a new point shapefile when vector grid features have a common attribute?

I have a very large shapefile that is composed of many cells. If there are 4 cells together that have the same attribute value, I must locate a point geometry, like below: Each side of the cell is ...
5
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1answer
195 views

Aggregating polygons with space between them

Im currently editing a large dataset that has large chunks removed throughout (buffered road network). The areas adjacent from each side have coinciding attributes, but have this large erased area in ...
5
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1answer
4k views

Create a new vector layer that fills space between other polygons in QGIS

I inherited a clipped (500m radius) land cover map containing vector layers of different land cover categories such as buildings, grass, roads, etc from a colleague. The empty (white) space in the ...
5
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1answer
546 views

How to cache PostGIS views?

Does anyone knows if there exists a caching system for views or queries in postgis? I have a system that gives information through a webpage using a postgis view as backend. The problem is that, ...
5
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3answers
13k views

Hover/Popup feature problem

im really having an issue here. I am trying to realise a map where i can hover over the features and they get highlighted (works), then i want to be able to click them (works) , i also want a div to ...
5
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1answer
148 views

Where to put vector layers with different CRS in a PostGIS database?

We have a PostGIS database with vector data with CRS British National Grid EPSG:27700. It is accessed remotely by users with QGIS. I now need to set up a similar vector layer for Northern Ireland, ...
5
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2answers
6k views

How to style a LineString feature to be red colored?

I try to add Features with LineString geometries in different colors to a ol.source.Vector. I tried to do this with the following code: var myFeature = new ol.Feature({ geometry : new ol.geom....
5
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1answer
489 views

Which system of units does the unit 'degree' belong to?

Let us say that I would like to store latitudes and longitudes like this: lat 35 degree long 80 degree Which system of units does the unit 'degree' belong to? It is not really a SI unit nor a ...
5
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1answer
1k views

How to compare two sets of points in QGIS?

I have two point layers with XYZ data; one set are points measured in the field and the second set is a Lidar data set. I want to check the accuracy of the Lidar in comparison to the measured data. ...
5
votes
2answers
5k views

Add rectangle polygon

I have a polygon shapefile layer. I want to add a rectangle polygon (just like in Arcmap), and another one using the previous polygon edge. I need it to be accurate, my hands do not meet this ...
5
votes
3answers
1k views

How to measure the distance of multiple points to a line

I have two shapefiles in QGIS to which I am trying to find the distances between. I have a shoreline which is a vector line and then I have hundreds of data points in the ocean. What I am trying to ...
5
votes
2answers
602 views

How to download Leaflet vectors in GPX format?

I would like to use the leaflet.draw plugin to allow users to digitize vectors on the map. At the end the data should be downloadable as a GPX-file. Is there any sample that shows how this can be ...
5
votes
3answers
3k views

How to update feature positions with clustering in OpenLayers?

I have an OpenLayers 2.12 map with a vector layer with a cluster strategy. All the static behavior is how I want it. Now I'd like to add the possibility to update the features' position. I do this ...
5
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3answers
3k views

Calculate neighborhood statistics for polygons?

I've been searching around for the answer to this (including here) and have yet to find it. I'm interested in finding out how to calculate a 'neighborhood sum' for vector, polygon data. I am aware ...
5
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4answers
13k views

Free Mercator, Vector Maps [closed]

Are there any free, vector, mercator projection maps available online? I'm not wanting satellite imagery, but more a stylized map along the lines of this: However, I need it to be vector-based such ...
5
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1answer
6k views

Sketch event in Openlayers 3 drawing interaction

For drawing Polygon in OpenLayers 2 we could use as follow: function drawEnd(){ ... } function putPoint(){ ... } function sketchModified(){ ... } function cancel(){ ... } var ...
5
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1answer
3k views

How to cache and server pre-rendered vector tiles in pbf format?

I want to serve vector tiles server in pbf format. For that I used Mapnik-vector-tiles which is bundled by avecado. Using avecado_server i can render pbf tiles on the fly using ./avecado_server -b ...
5
votes
1answer
549 views

OpenLayers Only draw features in a vector layer within view

I am dealing with a kml that I am importing into openlayers as a vector layer. This kml has many features so it dramatically slows down the web app. I would like to make it so only the features within ...
5
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1answer
805 views

One vector data layer with different styles in QGIS

I have one layer of vector data that I would like to show in two different styles. Is there a way of accomplishing this in QGIS? I've solved it now by duplicating the the vector layer and add ...
5
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1answer
448 views

LiDAR Feature extraction specifications/standards

I have vector data representing forests/trees/buildings that have been automatically extracted from LiDAR data. I am looking for specification/guidance for LiDAR derived products, or any standard for ...
5
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3answers
2k views

Vector Mapping for iOS?

Are there any vector map data providers with API's, that i can use to build my app on iOS natively (not on a webview). Specifically im looking for: For a library/framework that uses existing map ...
5
votes
1answer
250 views

Grid Analysis from samples data

I'm trying to analyze set of samples into vector grids in order to generate average data in corresponding grid.I'm working with 50m separated grids but the size of grid may change over time.That's why ...