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Questions tagged [polygon]

On a map, a closed shape defined by a connected sequence of x,y coordinate pairs, where the first and last coordinate pair are the same and all other pairs are unique.

9
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814 views

How can I merge adjacent polygons and return all (adjacent and not adjacent) as Multipolygon?

I have a postgres database with administrative boundaries and their geometry. Each of those boundaries have an ident number. What I want to achieve: First I want to select all rows which are ...
5
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0answers
59 views

Clipping rasters to mask layer QGIS 2.18, 3.4, 3.6 not working

Having a problem clipping a singleband GEOTIFF of Canadian land uses to a vector Quebec provincial boundary. When I do Raster -> Extraction -> Clip by mask layer, the program processes endlessly. I ...
5
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0answers
338 views

How to get or assign vertex id to polygon vertices and use these as vertex label using pyqgis?

I want to create parcels (polygons/polyline) maps with the vertices labeled incrementally by vertex id using pyqgis/QGIS. I normally do this by converting the polygon/polyline to point layer and ...
4
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0answers
68 views

Creating Raster that sums up input polygons using QGIS?

I am using QGIS and I have a shapefile with buildings. From these buildings, I have built Buffer with variegating radius. The Buffer also have data about the demand for Parking spots for each building....
4
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0answers
249 views

QGIS Zonal Statistics for polygons is missing results?

I am carrying out an analysis using QGIS 2.14.1 where I am dealing with point data that have been randomly displaced by either up to 2 Km or 5 Km. I have generated a buffer of the appropriate radius ...
4
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0answers
326 views

How to create text buffer in the legend- QGIS 2.18?

I work with this polygon layer and this is my map composer: I used the labels with Text Buffer (yellow and red), and I try to find how I can make the same text buffer in the layer name in the legend. ...
4
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0answers
640 views

What is the best way to display a large shapefile (with polygons) as a layer on a leaflet map?

I have a leaflet map of the UK with around ~2000 points total points and a bit of metadata loading for each point with two side-panels showing the metadata. These points are drawn from several tables ...
4
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0answers
457 views

Clip of polygons does not work properly by invalid geometry

I want to clip a polygon shapefile by another polygon shapefile. Input polygon is the green one (first), clip polygon is the light blue one (second) and the result should look like the dark blue one (...
4
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0answers
894 views

Find Distance Between Two Polygons

Given two polygons (point, line, or up to 8 vertices) I need to be able to calculate the shortest distance between them via code I write or a call to an API (I haven't been able to find one that does ...
4
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0answers
206 views

Reshaping polygons while preserving area

I'm looking to manually skew the shapes of areal polygons, but need to ensure their areas are not altered. Is anyone aware of any GIS tools or programming workflows that exist for manually reshaping ...
3
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0answers
31 views

Creating equidistant sampling points in polygon in QGIS 3.6.0?

I have figured out how to add random points inside polygon boundaries. Although this works well, nevertheless I need a few different things to happen for my application. What I would like to do is ...
3
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0answers
47 views

Unable to compute intersection between two polygons using PyQGIS?

I have two polygons in different layers. I am trying to find the intersect between the two polygons. Below a figure showing my test case. I initially wanted to find the intersect between the green ...
3
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0answers
583 views

Fastest way to union a set of polygons in R

I want to find the fastest way to union a set of polygons into one large polygon. Lets first get some data: # Load libraries library('raster') library('geosphere') library('mapview') library(...
3
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0answers
46 views

Dynamic filtering based on selected Layer in ArcGIS Desktop?

I am not sure this is even possible, I have about 38 geographical polygon layers showing areas of the UK, I also have a query (point layer) that shows all of the offices around the uk. What I am ...
3
votes
0answers
109 views

Why do I get invalid elements (polygons), when smoothing a vector layer (smooth geometry)?

The problem occurs, when using the commands "Smooth geometry" or "v.generalize.smooth" in QGIS. The shapefile, which I want to smooth, shows a flood water level and looks like this: The water level ...
3
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0answers
92 views

Displaying overlaping polygons and popups in the qgis2web plugin?

I'm total noobie when it comes to using qgis2web, CSS and HTML. The issue I'm having is displaying overlapping multipart polygons within the same shapefile (some of which are the same shape, but with ...
3
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0answers
426 views

Near Tool in QGIS

I am looking for an equivalent to the Near- Tool from ArcMap in QGIS. I have a Polygon Layer with potential areas for a new school and need to calculate the distance (in meters) to a point layer (with ...
3
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0answers
157 views

Flat-ended buffers on touching polygon features in QGIS?

Please note that emphasis is on POLYGON here NOT POLYLINES! I need Buffer/s on one polygon, with two touching features and straight touching parts after difference has been applied I do not want ...
3
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0answers
158 views

Fill in spaces between polygon features, voronoi style

I'm looking for a way to merge polygons across the empty space between them with a Voronoi-type result. There is a very similar question here, but the approaches outlined in the comments did not ...
3
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0answers
65 views

Constructing contiguous regions with similar properties by graph partitioning

I have census data for census output areas. Each area is a geographical region. I would like to partition these areas into contiguous super-regions with similar properties. For example, in each area ...
3
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0answers
64 views

QGIS - Layer missing polygons after pointsfile transformation

I'm using pointsfile transformation in QGIS for the georeferentiation of my layers. After the transformation the result some times has polygons missing like here: Why is this happening? How do I ...
3
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0answers
570 views

Troubleshoot with “Split selected features with selected line from another layer”

I am trying to use the "Split selected features with selected line from another layer" tool from the plugin Digitizing Tools in QGIS. Sometimes, this tool works with my shapefiles but sometimes it ...
3
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0answers
153 views

Can I reorder the points in a GEOS LineString?

Using libgeos, when I buffer() a polygon and then getExteriorRing() [to make a slightly smaller outline copy of the polygon just inside the original], it seems that which point on the new geometry is ...
3
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0answers
49 views

How do you show agreement between polygons based on hand-drawn maps?

I'm somewhat new to GIS, coming from a linguistic background, and now I'm trying to make QGIS do something that I want from that background. I have some hand drawn maps with certain areas of the ...
3
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0answers
171 views

Adjacency matrix for polygons using Java

I am trying to create an adjacency matrix from a set of polygons. That is, I have a bunch of polygons and I want to identify which polygons have a common edge or "touch" each other. Once I find this ...
3
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0answers
240 views

Create polygons from many small. Expand to include space between

I'm just a programmer without GIS-skills as such. Hence this question: Intro: I have a lot of polygons; actually each private-owned real estate in my country. I also have "counties" as polygons. In ...
3
votes
0answers
487 views

Polygon Layer Cleaning with QGIS

I have a little situation with my data. I have vectorized a raster layer, and now I have some issues with the geometries, as you can see in the picture. Most of errors I have are like this one. ...
3
votes
0answers
307 views

Why do each of my buffer-polygons have different areas

I`m using Qgis 2.2 and 2.4 and loaded a wms-map using the coordinate system ERTS89 UTM 32N. I set 8 points (all in on shp-fileand in UTM 32N) on various locations on the map. After that i created a ...
3
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0answers
354 views

What is the area that OGR extracts from the (geometry) shp files for polygons?

The ESRI July 1998 technical documentation for polygon shapefiles at page 10 makes no mention of either area measures or length measures (apart from byte/record-layout matters). Yet OGR enables me to ...
3
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0answers
163 views

Polygon parcel division in python

Is there an open source tool or module in python that does parcel division of polygons like in ArcEditor?
3
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0answers
194 views

CartoCSS: Don't show border between adjacent polygons

In OSM, riverbeds are created as multiple adjacent or even overlapping polygons. When styling these polygons in CartoCSS with a border, the overlapping can be seen: I'd like to hide that line ...
3
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0answers
599 views

Closest set of points to another set of (predefined) points

I have 10 sets of points which I call templates that I have manually classified from 0 to 10. Each point is a X, Y coordinate in a text file. Each template has 5-8 points. I have new sets of points ...
3
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0answers
752 views

Can't find point/polygon intersect using QGIS (Windows only)

Below I describe the method I am using. I have two machines: ubuntu linux, qgis 1.4 - intersection works WIN xp, qgis 1.8 - intersection does not work Hopefully, someone will find what I am doing ...
2
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0answers
34 views

Graduated color display of overlapping polygons in ArcMap

Is there a way to display overlapping polygons in a graduated color symbology based on the level of overlap within the same feature layer? For example, in one area of the map there are two polygons ...
2
votes
0answers
21 views

Removing a 'non-gap' gap from a polygon that straddles +/- 180 longitude; looking for an R-based, code solution

I am working with a set of polygons from here: http://lme.edc.uri.edu/index.php/digital-data. In the artic, there are several polygons that straddle the +/- 180 longitude line. These are single ...
2
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0answers
56 views

Extracting polygons from mbtiles

Currently, one can extract features within a bounding box from an mbtiles file using tilelive-copy. However there is no way to extract features within a polygon from an mbtiles file. The mbtiles-...
2
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0answers
29 views

Creating a continuous raster road network using Polygon to Raster in ArcGIS Pro?

I have a polygon forest road network that I would like to turn into a raster. I have attempted to use the ArcGIS Polygon to Raster tool, but whenever the majority of a cell falls outside of the ...
2
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0answers
101 views

Copy polygons to another layer with different attribute

I am working in QGIS 3.0.2-Girona. I am digitizing images in which there are rocks that can be encrusted, totally or partially, by algae. I want to have a polygon for the rock and one for the algae. ...
2
votes
0answers
41 views

Calculating individual width between buildings using ArcMap?

I have a building footprint shapefile and I would like to calculate the individual width between each building (i.e., adjacent building and across the street). I have looked at solutions which use the ...
2
votes
0answers
233 views

How to find a polygon error in QGIS?

I loaded the following multipart polygon in QGIS which consists of three separate polygons. The highlighted (yellow) polygon consists of the bigger upper part and the smaller lower part. My aim is to ...
2
votes
0answers
105 views

Reproject vector layer in QGIS?

I want to warp a vector layer (set of polygons, but not a raster map) to fit a map. The problem is, the vector layer coordinates are from 0 to 360 and the basemap layer coordinates are from -180 to ...
2
votes
0answers
76 views

Summing clipped rasters under polygon using PostGIS?

I have a multiband population raster and geometry table in postgres. For every polygon, I'm trying to sum the population (rast) that is contained in that polygon (geom). This is how I originally ...
2
votes
0answers
82 views

Clipper: Split polygon layer with line layer - generates empty layer

I am using QGIS 2.14.3 Essen. I wanted to split several polygons with several lines. Both layer are in GK4 coordinate system (used layers generated by: QGIS right-click on layer -> Save as... ) and ...
2
votes
0answers
120 views

Removing slivers from IPolygon using ArcObjects?

ArcGIS Desktop Basic 10.1 with Spatial Analyst and 3D Analyst I have multiple neighboring polygons which I unionize. On occasion the result has slivers where the multiple polygons meet. I have been ...
2
votes
0answers
75 views

Expanding polygons and clipping at midpoint?

I have several separate shapefiles with polygon features. The end goal is to maintain separate shapefiles for each polygon but form a contiguous, non-overlapping coverage for my area. Basically, I ...
2
votes
0answers
72 views

Converting polyline to polygon without 'Feature to Polygon'

I am attempting to create a script tool to automate some processes at work. Part of this process was to manually cut (using Cut under Editor) a buffer. My approach to this has been to try and split ...
2
votes
0answers
135 views

Calculating combined area of multiple polygons by counting overlapping area only once in R?

I'm using a shapefile in which polygons represent the geographic distribution of species. I need to calculate the combined range of several species sets, but the overlapping areas should be counted ...
2
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0answers
33 views

Is it any way to add more that one OpenLayers.DynamicMeasure?

I would like to make a feature to my webapp, which I could show sum of two(or more) Polygons.. But... When Im drawing another polygon, earlier one disappeared, when I change this.layer.addFeatures([...
2
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0answers
131 views

Building footprint polygon simplification / generalisation

I'm looking for implementations of polygon simplification algorithms that preserve topology and overall rectilinearity. The input data is building footprints which often have squarish protrusions and ...
2
votes
0answers
249 views

Insert a MultiPolygon in a PostGIS table with MapInfo?

I'm using MapInfo 16 to edit a PostGIS table through ODBC driver. The geometry column type of my table is MultiPolygon. The value in spatialtype colmun of a record in mapinfo.mapinfo_mapcatalog table ...