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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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10
votes
2answers
833 views

What's the batched Refactor Fields tool “field mapping” syntax in QGIS?

In QGIS, there is this nice tool "Refactor Fields" in the Processing Toolbox : Using it on a single layer is fairly straightforward. However, when you plan on using it in a batch mode, one can see ...
10
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2answers
2k views

What's the best way to display thousands of polygons in Openlayers?

I am trying to create an Openlayers map that will display thousands of polygons. And when the user clicks on each, I want some of the metadata to display. Working with this large of a dataset seems ...
10
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2answers
2k views

What does vector tiled map mean?

I'm working on an application that renders GeoJSON into OpenLayers map. The idea is about not having PNG images downloaded from external services (OSM or Bing) but having geo-information in GeoJSON ...
10
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1answer
3k views

Why do vectors disappears when zooming in?

I have imported a .gpx file into qgis and separated the track waypoints using Vector > GPS > GPS tools. When viewing at full extent I can see the original track and component waypoints. However when ...
10
votes
0answers
4k views

Import Vector data to QGIS from pdf and apply georeference [closed]

I am Using QGIS 2.14. I have a PDF created by Mapinfo, it contains multiple layers of vector data that I can open as separate vector layers in QGIS. However no map projection data was saved to the ...
9
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3answers
21k views

How to connect OpenLayers to PostGIS data?

I have read in OpenLayers how to load KML, GeoJSON etc. vector files in OpenLayers. But how can I connect to PostGIS data. If not, why should I upload my data to PostGIS then instead of directly ...
9
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4answers
3k views

Making QGIS attribute table field automatic?

I'm working in a way to make hydrologic projects using QGIS and an Excel worksheet that I have. To do this, I want to extract some information of the lines, included in a vector layer, which ...
9
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3answers
2k views

Creating polygon in empty space from other polygons in QGIS?

I have a vector file where I have made some polygons but between the polygons I have empty space. This entire empty space I would like to make one whole polygon but until now I can't figure out the ...
9
votes
2answers
369 views

Create line segments at point coordinates in QGIS

I have a point vector layer with angle field. How can I create line segments at these points with certain length and angle? I did this with style options but I need this physically as lines vector ...
9
votes
4answers
29k views

Calculating minimum distance between points and polygons in QGIS?

I have two vector layers: one point and one polygon and I want to calculate the minimum distance of each point from the polygons (ie the distance from the closest point of the closest polygon). Is ...
9
votes
3answers
8k views

How to change layer transparency without changing border lines?

I have a raster image of elevations. I have added a vector shapefile that contains local political divisions. I want to keep the elevation colors, but I want to keep the black lines representing the ...
9
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2answers
13k views

How to clip a vector feature to the extent of an existing raster dataset using arcpy

I have a clipped raster dataset with polylines (from the contour tool) overlayed (see attached). I am trying to clip the polylines to the extent of the raster dataset, which seems simple enough, but ...
9
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3answers
9k views

Finding nearest raster cell value based on vector point?

I have two layers in ArcGIS: One is a vector point and the other is a raster layer. I want to append the value of the raster data grid to the vector point. The problem is the vector point is away from ...
9
votes
2answers
478 views

What spatially-aware GUI administration softwares exist for PostgreSQL/PostGIS?

Most of my experience with PostgreSQL has been pgAdminIII and psql, but I'm interested to know what others use. Is there PostgreSQL equivalent to SQL Server Management Studio (SSMS) and its ability ...
9
votes
1answer
1k views

How to reverse vertex ordering in polygons?

I am working with an Oracle spatial connection in QGIS through which I am accessing and editing a vector layer. I find that when I edit a geometry, the vertex ordering is reversed (to clockwise in the ...
8
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4answers
1k views

Understanding resolution in vector maps?

I'm developing a vector maps with detailed features such as road edges, cross walks, traffic lights , street lights etc., by using 3D points (x,y,z) without geo-referencing, generated from stereo ...
8
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3answers
3k views

30,000 data points… can this be reasonably served using openlayers?

I'm trying to tackle a web GIS problem and need to figure out the best strategy. I have a map with 30,000 cells on it forming a grid for the province of Alberta. I have a list of data points for ...
8
votes
1answer
1k views

Different layer styles at different scales in QGIS?

I would like to be able to show a basic style for a layer at a large scale, e.g. GB-wide, with all polygons the same, but for this to change at a smaller scale, e.g. 1:25K, to differentiate between ...
8
votes
2answers
4k views

Clipping Error 1: Cutline polygon is invalid

I used the sample files located at this URL to learn QGIS: https://qgis.org/downloads/data/. I tried to clip SR_50M_alaska_nad.tif using a shapefile as a mask (alaska.shp). The problem is I ...
8
votes
3answers
10k views

Removing columns in a SpatialPolygonsDataFrame in R?

My spatial polygon data frame (SPDF) contains too many columns (variables) and I want to remove most of the columns entirely. I know how to do this with a regular data frame in R, but I am unsure ...
8
votes
1answer
8k views

OpenLayers WFS vector layer

I'm trying to add a vector layer with a WFS layer and it's not working. Can anyone point a solution? OpenLayers code: var wfs = new OpenLayers.Layer.Vector( "Stavros Features", ...
8
votes
3answers
5k views

How to create a new Spatialite database in QGIS

I've been trying to create a new spatialite database within QGIS 1.8 (SpatiaLite Version 3.0.1; QSpatialite 6.0.3) and keep getting this error: "The SQL query seems to be invalid. no such table: ...
8
votes
1answer
653 views

How to merge two shapefiles with partial difference in QGIS?

As illustrated below, a copy of the same shapefile was given to two persons who edited them partially by changing the attributes of different features. I would like to know how to merge the two ...
8
votes
1answer
8k views

Google maps android vector rendering : how do they make it that fast?

Most of the question is in the title. If you are on android (I believe its the same on IOS) and use maps you will notice the quality of the maps app and how the vector maps are drawn in a very fluid ...
8
votes
1answer
1k views

Split up shapefile into little shapefiles

I have a very large shapefile (all the roads in RI). I need to split it up into chunks so that I can process the file with multiple worker threads in Python. So far I have created a grid in QGIS that ...
8
votes
1answer
3k views

Where can I find a Unesco World Heritage List as boundaries?

I was wondering if anyone knows where to find the UNESCO world heritage list with boundaries? I can extract point data from the json feed for the map on the website http://whc.unesco.org/en/list via ...
8
votes
1answer
15k views

QGIS: “Invalid geometry” even after using validity checker and v.clean

I'm trying to intersect two layers in QGIS, similar to this unanswered question. I've performed Vector > Geometry Tools > Check Geometry Validity and I've run GRASS's v.clean, per these questions. I'...
8
votes
3answers
359 views

Cutting Polygons in QGIS at a specific distance from a feature in another layer

I would like to be able to cut polygons such as the one below, in QGIS, at a set distance either side of a specified feature on another layer, in this case a footpath line from OS Mastermap. In this ...
8
votes
2answers
780 views

Hashing functions for GIS data

I would like to take geometries from a vector dataset and reduce them to a hash. This hash would then be used to verify the integrity of that data and also identify identical geometries. Do any ...
8
votes
1answer
350 views

Accessing “Save Vector Layer As” algorithm in QGIS Processing Model?

I'm building a Processing Model in QGIS that ultimately exports a points shapefile (vector layer) as a CSV in a different coordinate system than the shapefile. I ordinarily accomplish this in the "...
8
votes
2answers
1k views

How to convert a vector boundary to a raster map?

I need to output a PNG file of a raster map overlayed with boundaries present in a vector map. The problem is, the r.out.png script only exports a raster map. My boundaries are in a vector format. ...
8
votes
3answers
2k views

Create interactive map with no server

I have managed to build a great web mapping application using tiles created from GeoWebCache and a custom gridset, but I now need to add an overlay to the base maps. The only interactivity I need is a ...
8
votes
1answer
90 views

Visualising most likely direction of migration given points with ages using R?

I have a question about how best to visualise the predicted direction of migration given a set of points with estimated ages. Imagine I have a set of geo coordinates, representing communities. For ...
8
votes
2answers
361 views

Estimating resolution of vector data?

I got an old vector dataset with polygons covering a continent. The data was first published on paper at scale 1:5 000 000 and was later digitalized. I don't have the original data and no information ...
7
votes
4answers
9k views

Split Lines at Intersection of Other Lines

I have two line layers (roads and contours in this example) and I would like to split the roads layer every time it crosses/intersects a feature on the contour layer. I can't seem to find a tool that ...
7
votes
2answers
1k views

Creating “average” polygon?

I found this thread in the old ESRI forums with the same type of problem I am facing today. The solution to the problem is explained in little detail and since I am not an expert, I was wondering if ...
7
votes
4answers
20k views

Customizing Popups in Openlayers

Is it possible to customize the shape of popups in OpenLayers? For example, I am creating a pop-up using the following approach: var popup = new OpenLayers.Popup.FramedCloud( "popup", ...
7
votes
4answers
12k views

How to convert a vector map to raster in Qgis?

I am creating a thematic map (vector data) with different classes. How to convert this vector map to a raster map, keeping the classification?
7
votes
2answers
8k views

How do I find vector line bearing in QGIS or GRASS?

How can one extract the bearings from a set of lines in a vector file? I'm trying to find the bearings of several straight vector line segments (simplified contour lines, actually) and can't figure ...
7
votes
4answers
6k views

How to identify and eliminate overlaying polygons in Quantum GIS?

I have a shapefile with polygons and now, not sure why, most of the polygons became duplicated and overlaid, i.e. when i click to selected one, i get two selected... How do i identify those polygons ...
7
votes
3answers
439 views

Select all polygons that are completely within a circular buffer

I made several buffers around some points. Now I want to select all polygons that are completely within this buffer. My problem is that I also get the polygons that are partially outside of the buffer....
7
votes
1answer
2k views

Programmable buffers using GDAL and python

Is there a way to programmatically generate buffer layers for vector layers using GDAL and python?
7
votes
4answers
838 views

Comparing 2 vector files

I'm looking for a tool which compares two vector files (eg shapefiles). Eg 2 versions of a river network. Quite a lot of the records are equal, but some are different. A possible output would be eg a ...
7
votes
3answers
855 views

How to get a list of adjacent lots to a road in ArcMAP and PostGIS/QGIS?

In the following map, I have: A line / road layer A parcel / lot layer The Task: Find and count the list of lots adjacent to the road with their types (parcel_type is a field in the parcel layer) ...
7
votes
5answers
3k views

WFS to Vector Tiles

Is there, by some miracle, an existing piece of software which is able to convert a (3rd party, GeoServer) WFS feed into vector tiles? In a utopian world, this would happen on the fly, but a download/...
7
votes
2answers
3k views

Convert points to lines with Python GDAL

I have a dictionary with points. The points are derived from a raster (see image below). The points are not sorted and are not in order. The dictionary looks for example like this: pointDict = {0: (...
7
votes
5answers
9k views

Merge overlapping lines in ArcGIS

I have a polyline shapefile containing a number of lines, some of which overlap. By overlap, I mean that they follow exactly the same path for some of their route, but also have bits that are not ...
7
votes
3answers
4k views

Creating a raster surface of overlaps from vector polygon shapefiles?

Basically what I'm trying to do (in ArcGIS 10) is to compare three vector files in order to create a 'comparison' raster layer. I tried using Data Comparison (under Data Management tools) but it didn'...
7
votes
2answers
5k views

Converting Shapefiles to Mapbox Vector Tiles

We are currently hosting OSM vector tiles on our mapping server (courtesy osm2vectortiles and tilesever-gl). Now I'm trying to convert our own shapefiles into the same Mapbox Vector Tile format so we ...
7
votes
2answers
1k views

Create shapefile of raster outline using python

I want to create a single bounding shapefile polygon of valid pixels in raster data (GeoTIFF) using python. I need something efficient as I need to do this for hundreds of rasters. I had thought of ...