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.

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4
votes
1answer
406 views

Edit existing polygons to include several new nodes

I want to define catchments which are quite large from vector contour data. I normally start zoomed out to define the catchment generally as it is easier to see. I then zoom in and refine the ...
11
votes
3answers
2k views

Combining corner-touching polygons into a single feature

I have created a polygon layer from rasters, and only have a single classification ID (and calculated acres) for each polygon. I would like to "dissolve" all touching features into larger, individual ...
2
votes
1answer
48 views

Polygons drawn in editable feature service through Collector cause reverse or negative geometry

I have been experiencing a very odd situation where polygons – when drawn in an editable feature service through Collector on iPad – will draw and save, then seconds later the geometry will be ...
4
votes
1answer
78 views

Find out if overlaying polyline matches polygon centerline in qgis

I have a polygon and a polyline and I need to find a scientific way of how close that polyline is to the actual polygon centerline. Is there any way of doing this in qgis? Any extensions, models, ...
1
vote
2answers
86 views

How to combine two polyline shapefile together

Here is my question Two shapefile: * A: represent the outer boundary of the city area * B: represent the inner boundaries of the city divisions. I want to * Combine these two shapefile * ...
0
votes
1answer
186 views

calculate distance between points crossing the antimeridian

How can I calculate the distance between two points (lon/lat) if any of the points exceeds the antimeridian (+-180 longitude)? Im using the distVincentyEllipsoid {geosphere} to calculate the shortest ...
0
votes
2answers
25 views

Keeping attribute table when converting from polygon-based feature layer to grid layer

I am trying to transfer (or extract) attribute data from a polygon-feature class to point data. I can do this for a grid file using the Spatial Analyst-Extraction-Extract multi-values to points ...
2
votes
1answer
36 views

How can I split a polygon by network line in QGIS?

I have a road network as line layer and a land cover as polygon layer, I want to find number of subpolygon for each polygon that divided by line layer in QGIS? I used union function in Geoprocessing ...
1
vote
1answer
27 views

transformations from a sphere using R for raster and polygon data [duplicate]

I am planning on using the MODIS burned area products which were produced by Maryland University. These come as either polygons or rasters. In the user guide it says A shapefile version of the MCD45 ...
2
votes
1answer
30 views

Catchment boundary polygon from catchment area raster

I am trying to generate a catchment area polygon from a digital elevation model. I am using SAGA tools in QGIS and used the Flow Accumulation (Flow Tracing) tool to generate a catchment area raster ...
0
votes
0answers
28 views

Adding custom vertices to a Leftlet LineString / Polyline

I have a normal Leaflet Draw page here, when I'm not in editing mode I would like to have custom vertex icon in some of the vertices that will also respond to click events, showing a popup. I looked ...
4
votes
2answers
76 views

How to find 2nd order polygon neighbors? (and 3rd, 4th etc.)

I have a shapefile of contiguous polygons and for each pair of polygons, I need to know how many polygons are between them, following an neighboring/bordering approach. The output is likely to be a ...
1
vote
1answer
35 views

Highlighting selected polygon features without filling colors in QGIS while editing?

When editing in QGIS, how can I highlight the selected polygon features without filling them with colors i.e. just outline the polygon boundary?
2
votes
1answer
51 views

Create frequency polygon from overlapping features in another polygon

Mac 10.9.5; QGIS 2.8.4-Wien; history and unioned data, in GDA94, zone 55 here. I have a polygon of fire history with a number of overlapping features. I want to create a new polygon for fire ...
2
votes
1answer
17 views

WFS Filter performed before or after reprojection?

I'm trying to perform a WFS filter with a polygon in EPSG:3031, (the native projection is EPSG:4326 I think). And I'm aware that WFS/GeoServer supports reprojection on the fly. But will the features ...
29
votes
4answers
7k views

How can I calculate the average width of a polygon?

I'm interested in examining the average width of a polygon that represents the road surface. I also have the road centerline as a vector (which is sometimes not exactly in the center). In this example ...
2
votes
2answers
111 views

Average width of irregular polygons QGIS 2.12.0 Lyon

I'm interested in examining the average width of streets, that are irregular polygons, for a project. I'm using QGIS 2.12.0 Lyon, and have lines (power cables) and Polygons (streets) as layers. For ...
4
votes
1answer
32 views

How to extract a buffer layer from a vast amount of individual buffers around polygons using ArcMap?

I have a vector layer containing nearly 8000 singlepart polygons. It looks like this: I want statistics on the area that is further than 2,5m away from any border. I thought I could do this by ...
0
votes
0answers
17 views

Extracting coordinates and climatic conditions of grids where species polygon overlaps with the climatic layer in R?

I have species’ shapefiles and climatic raster files. The climatic file is in 50 * 50 km equal area grid. Now, I want to calculate the climatic conditions in each grid cell where species polygon ...
5
votes
3answers
86 views

Merge a list of spatial polygon objects in R

I have a list of spatial buffers (30000 buffers) that I built with the function lapply: buff.pts <- lapply(1:nrow(pts.prj), FUN=function(l){ buff <- gBuffer(pts.prj[l,], width=1000) ## 1km ...
28
votes
8answers
31k views

Removing small spaces (slivers) between polygons?

I have a set of polygons representing administrative districts. The districts were digitized by hand, and there are small spaces (slivers) between polygons where the polygons should be touching. How ...
2
votes
1answer
460 views

Invalid join selectivity error in postgis 2.1.3

I have 2 tables, one for points and one for polygons. I want to find points falling within theese polygons, so I quered: select p.id, l.id from points p inner join polys l on st_contains(l.geom, ...
3
votes
3answers
197 views

Remove islands and completely surrounded polygons after polygonization with QGIS

I have a line map of buildings in a city. I was able to correctly polygonize the buildings in QGIS with the Polygonize processing algorithm. All the holes/islands became features as expected. Now I ...
10
votes
4answers
3k views

OpenStreetMap Neighborhood Boundaries

Is it possible to download neighborhood boundaries from OpenStreetMap? I see on maps that they often indicate neighborhood names; is there a way to retrieve their coordinates and boundary polygon ...
12
votes
7answers
4k views

Where can I get neighborhood boundaries?

Besides Zillow's creative-commons licensed neighborhood boundaries shapefiles, what sources of neighborhood boundaries are there? Not just in the US, but all over the world. Free/open source is ...
3
votes
1answer
42 views

Is it possible to remove small polygons from Census Block shapefile?

I just pulled up a shapefile that plots census blocks (TIGER product) using Quantum and I noticed that there are well over 1000 small polygons that aren't census blocks that are (I assume) used to ...
1
vote
0answers
38 views

How to correctly rasterize a polygon which crosses 180E longitude?

I want to rasterize a polygon wich crosses 180E lon with gdal_rasterize. The polygon is in the WGS84 projection. I used the following command: gdal_rasterize -burn 1 -of GTiff -ot Byte -ts 1500 ...
2
votes
1answer
56 views

Selecting many maximum points within polygons

I've got a point layer with three values such as high, age etc. and polygon layer with many forest area. What I want to do is to select the 100 maximum (highest) points in every polygon. I can't do ...
1
vote
1answer
47 views

What is the easiest way to create rings from existing polygons?

I have been given a shapefile from a client that features pivots, yet they were recorded as 10 circles overlapping. The software my company uses requires that these polygons be rings that don't ...
1
vote
1answer
66 views

How to map geoJSON polygon from a url request in python

Using Python I have loaded json data from the url http://environment.data.gov.uk/flood-monitoring/id/floods and have found that the flood areas encoded as geoJSON polygons are displayed as url links. ...
6
votes
1answer
5k views

How can I transform a polygon to a linestring in QGIS?

I have a polygon, imported from a shapefile in QGIS. I would like transform it to a linestring instead so I can save it as a GPX file later. How can I transform a polygon to a linestring in QGIS?
1
vote
1answer
28 views

How to assign the attributes of the largest overlapping polygon area to each overlapping gridcell?

I am new to R, and I am trying to use it to calculate the areas of polygons that overlap with each gridcell, in order to assign the attributes of the largest overlapping polygon area to the ...
4
votes
1answer
57 views

Add column to point data of whether point falls inside polygon

This seems like it should be fairly simple, but have been having quite a bit of trouble. I am no expert in ArcGIS for Desktop I have: one layer of points, and 4 polygons, which partly overlap I can ...
2
votes
2answers
67 views

Drawing a polygon of a given area

First, I am using QGIS 2.8.2. I have GPS waypoints and satellite imagery and am trying to draw polygons. This is easy enough, but I need to make sure each polygon is 1ha exactly. Is there a way to ...
0
votes
0answers
132 views

How to calculate the number of markers with in a polygon in openlayers3

I am using https://github.com/tombatossals/angular-openlayers-directive openlayers angular repository and plotting markers on the map as shown below <!DOCTYPE html> <html ...
2
votes
1answer
46 views

Can't Find the Split selected features with selected line from another layer tool

I'm trying to split a selected polygon features with a selected line from another feature layer. I, however, can't seem to get the tool for this to show up in my advanced digitize toolbar. In ...
1
vote
0answers
21 views

Convert a polygon grid into an edge table

I'm working on a robotics project. I've got a rectangular grid (polygon shape file) that is a navigateable/routable region (i.e. I can travel anywhere in this grid). That is I took my bounding area ...
6
votes
3answers
251 views

How to select specific rows of polygons from a grid in QGIS?

I have a polygon layer. I would like to select every second row of the polygons but not manually. Is there an expression to select every second row as seen on the picture with Select by expression in ...
6
votes
2answers
514 views

Automate Splitting Polygons Into Sections

I've searched for similar problems on this topic but can't find a solution. I need to split many, many, many cemetery sections into 8 (mostly) equal pieces each. Each section is for the most part ...
4
votes
3answers
968 views

Remove Holes Existing Within a Single Polygon for a specific area in Qgis

I have a shapefile that consists of a single polygon. I have gaps within the polygon that needs to be eliminated, but only the ones that are less than 200m2. I tried different ways but none of them ...
1
vote
0answers
55 views

Problem in polygon division using the union tool from QGIS

I am trying to overlay two polygon layers using the union tool from QGIS, to then compute the areas from the resulting polygons. However, in the resulting layer some polygons are not divided as ...
3
votes
2answers
56 views

How to calculate area in sq m - troubleshooting projection issues in a global dataset in QGIS

I am using QGIS version 2.12.3. I have 3 polygon shapefiles: A, B and the intersect of A and B, which we can call C. All I want is to add a field to the attributes table of each shapefile giving ...
0
votes
2answers
68 views

Dividing an irregular polygon into sub-regions

I am trying to divide an irregular polygon into equal widths and am having trouble understanding the proper tool to use. I am in possession of ArcGIS and am aware that the Parcel Editor is the closest ...
3
votes
1answer
68 views

How to create a fishnet/grid along a polyline or polygon

I am trying to generate a fishnet/grid along a line/polyline or polygon boundary in ArcGis 10.3 or QGIS. While it is totally intuitive and easy to generate a box-standard grid, what I am trying to do ...
2
votes
1answer
62 views

Converting Shapely MultiPolygon to Polygon: Technique doesn't always work

In order to get the exterior coordinates I need to convert a shapely MultiPolygon to a Polygon. I do it like this: if poly.geometry.type == 'Polygon': x, y = poly.geometry.exterior.xy elif ...
4
votes
4answers
4k views

Clip raster using shapefile into multiple rasters using ArcGIS Desktop?

I have a raster file representing a large area and a shapefile of 30 polygons representing watersheds. I would like to clip the raster with the shapefile to create 30 rasters representing each ...
2
votes
4answers
1k views

Polygon Shape Data for North America

Does anyone know where I can get data like this for north America (for use in SSRS). It does not have to be exploded. If I add Bing maps my 36 page PDF is 250MB when exported!
2
votes
0answers
102 views

Merge n number of adjacent polygons [closed]

I have over 17,000 individual polygons. I want to merge two adjacent polygons so that I finish with approximately 8,500 polygons. The polygons need to be merged based on location, merge two adjacent ...
0
votes
1answer
36 views

How to select congruent polygons in PostGIS?

Title says it all. What is the best way to select congruent polygons in PostGIS? CREATE TABLE polygon_a ( gid serial NOT NULL, geom geometry(Polygon, your_SRID), CONSTRAINT polygon_a_pkey PRIMARY KEY ...
2
votes
2answers
227 views

how can we save vector layer as a file in openlayers

Im using mapserver + openlayer for GIS API and im new to GIS. I'm done with drawing line, point and polygon features in openlayer. but not being able to save it in some shapefile afterwards i got to ...