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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5
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2answers
2k views

r - increase speed of crop, mask, & extract raster by many polygons

I'm extracting the area and percent cover of different land use types from a raster based on several thousand polygon boundaries. I've found that the extract function works much faster if I iterate ...
1
vote
2answers
33 views

How to compute the distance from the current polygon centroid to another in QGIS field calculator?

There is layer with polygons. I want to save in new field distance of every polygon's centroid to centroid of one particular polygon. To do this I should write some expression like this: ...
1
vote
1answer
30 views

extracting statistics from a raster within the extent of a polygon

I have a polygon representing the extent of a study area. This polygon is overlaid to a raster representing the quality of land, which is classified into 5 classes (from bad [1] to good [5]). I would ...
4
votes
3answers
4k views

Intersect (analysis) of polygons generating empty output

I have previously asked a question on determining the area of polygons with another polygon boundary. Determining the area of each polygon within a polygon boundary? I came to the conculsion that ...
0
votes
1answer
1k views

How to narrow the result from Nominatim with only cities and countries, no additional areas with the same name?

I'm trying to get WKT or GeoJson polygons of cities and countries from Nominatim (for example, Paris and France). I send a GET request but it returns me several results named "Paris" or "France". How ...
3
votes
1answer
509 views

postgis: cluster/group points based on distance

We have a set of thousands of points and want to group all of those which are within 100m distance from each other (to get the centroid from each group). A first idea was to build 100m buffers around ...
7
votes
0answers
608 views

Grouping analysis of points to divide polygon into n number of sub-regions using QGIS?

I'm attempting to create n sub-regions from a polygon based on a cluster analysis of a bunch of overlapping raster layers (physical layers, eg: depth, currents, waves). Briefly, I can create a ...
0
votes
1answer
211 views

Testing correlation between two polygon features

I am working on a project looking at county boundaries for the state of California. I have 2 polygon datasets with this same geographic boundary, and these datasets, when mapped individually, visually ...
2
votes
0answers
23 views

Intersect, Spatial Join?: One Line crossing Multiple Polygons, assigned wrong attribute

I am looking for any possible solutions to a problem I am encountering with ArcGIS. I am using census block groups (CBG) to assign streets an income level value based on their location within the ...
2
votes
0answers
25 views

Adding attribute data together within multiple polygons in QGIS? [duplicate]

In QGIS I have two vector layers, the first is a set of polygons and the second is a series of points. Each point has a numerical attribute associated with it and is located within one of the ...
4
votes
4answers
3k views

Percentage of polygon in one shapefile within polygon of another

I'm a newbie, apologies if this is obvious/has already been asked and answered but I couldn't find anything. I have two shapefiles: 1. an administrative boundary layer for a county in the UK known as ...
4
votes
1answer
41 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 ...
4
votes
2answers
117 views

Clip polygon using buffer

I'm very new to QGIS, so apologies if this is a daft question. I've been trying to resolve my problem for a couple of days and I can't get anywhere. I have searched for similar issues here on SE but ...
1
vote
3answers
790 views

“Identity” overlay in QGIS?

I have two polygon layers I'd like to overlay using QGIS or another open source tool. What I want as output is a polygon layer with the extent of one polygon, but with each polygon in that layer ...
2
votes
1answer
482 views

Extract data from netcdf using a shapefile polygon in python

I need to subset data from a NetCDF using a specific shapefile. The data are sea surface temperature and ocean color at 1/4 degree resolution. I have 4 polygons describing the US. Northeast ...
2
votes
1answer
46 views

Tutorial to create Shapefile based on Districts using ArcGIS for Desktop?

I have been tasked to create shapefile of Amritsar, India (will be incorporated into R programming language) So far, I see this 2-part video tutorial, where person is assigning numbers and icons, ...
2
votes
1answer
48 views

Selecting features of vector layers based on another vector layer using QGIS?

I am using QGIS 2.12.2. I am using three vector layers (point, polyline and polygon shapefiles) of the region of interest. Any advice in making the selections from one dataset based on the other ...
1
vote
1answer
412 views

Is it possible to draw polygons along Google Maps Polyline?

Web application has option that user draws polyline on Google Map. After he draws it, there is a button 'Add polygons', which should draw polygons along that line, based on some width and height in ...
0
votes
0answers
30 views

How to not display a layer, if its below a other semi transparent layer?

I have two polygon layers (PostGIS). One of them is semi transparent. If the other layer is below the semi-transparent one, it should not be displayed. My situation at the moment is: The grey ...
4
votes
1answer
52 views

Remove sliver gaps between polygons with R

Is there a way to eliminate the small "slivers" between polygons using R? The desired solution would create a new SpatialPolygonsDataFrame where the shared boundaries between polygons are coincident. ...
4
votes
1answer
593 views

How to give elevation information to a polygon feature class using existing TIN file ? (geological mapping)

I'm an ArcGIS 10.1 user. My issue: I have a printed form of a map which depicts geological bodies being surface rock occurence. Additionaly, there are elevation contour lines. I digitized the map by ...
0
votes
2answers
83 views

Adding one search box for multiple GeoJSON polygon layers?

Multiple GeoJSON markers can be combined to one group layer then search on a specific attribute but doesn't work for GeoJSON polygons. How to put multiple GeoJSON markers and polygons in one search ...
6
votes
3answers
78 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 ...
1
vote
1answer
182 views

how to find that two polygon boundaries are connected?

I am working on a Geo database where there is a layer with many polygons. i want to find that which polygons boundaries are connected so that i can create new layer from that polygons and which ...
2
votes
1answer
48 views

How to rasterize an object of class SpatialPolygonsDataframe in R

When I read a polygon shapefile into R using rgdal, it was imported as an object of class SpatialPolygonsDataframe. I need to rasterize the polygon, but the rasterize{raster} function requires it to ...
9
votes
6answers
8k views

How to remove only donut holes from polygons using ArcGIS Desktop?

I am using ArcGIS Desktop 10.0. I have a trick for removing the donut holes, which is converting the polygon to line and then creating polygon out of the lines and in the end merging all of them. ...
0
votes
1answer
193 views

How to merge polygons with ST_union

I have a similar problem, but I can't get the syntax correct. This refers to the following question: Merge polygons in CartoDB? I'm trying to merge multiple polygons into one (in this case, just ...
3
votes
1answer
419 views

Determine when I have crossed state line?

We are currently using the Google Maps API to get route information and total mileage but we would like to determine when we are crossing into a new state. When we return the route information we can ...
0
votes
0answers
25 views

How to bind event to Polygon inside polygon in google maps.?

I am drawing a polygon buffer in google maps api v3 and finding number of polygon objects lying inside it.(on click) I am using oracle spatial database. on each child polygon click i need to do some ...
4
votes
0answers
40 views

Buffer neighbouring polygons without overlap using QGIS

Is it possible to create a buffer around neighbouring polygons, so that the new polygons do not overlap? Preferably in QGIS but any other tool will do. So instead of the first result I would like ...
2
votes
1answer
55 views

Trouble adding proportional circles on top of symbolized polygon in ggplot2 map

Data: Zipped ea.ml1 shapefile can be found here, and the country outline can be downloaded here at the GADM site. I've been using the Ethiopia ESRI shapefile. Branch locations are here. Per the ...
1
vote
1answer
41 views

How to create custom discrete color scheme for polygon attributes in ggplot2?

Back again with more questions. :) Data: Zipped ea.ml1 shapefile can be found here, and the country outline can be downloaded here at the GADM site. I've been using the Ethiopia ESRI shapefile. As ...
0
votes
1answer
184 views

How to copy closed loop lines into polygon feature class

I'm trying to utilize line contour data to find the volumes of local depressions. To do this, I want to copy the closed loops formed by depression contours into a polygon feature class to find the ...
2
votes
0answers
25 views

Create polygon layer from point data with number attribute where polygon encloses n% of point data attribute value in QGIS [closed]

I have two sets of data, one is the CodePoint Open with the location of all of the uk postcodes, the second is from online form data from which I've extracted the postcode and telephone area code, and ...
4
votes
3answers
2k views

Clipping Vector File based on certain Raster Values using ArcGIS Desktop?

I need to clip a vector file based on certain values of a raster (Slope > 2%). I can´t find a direct way to do it. Trying to vectorize the raster first didn´t work. Is there an ArcGIS tool I could ...
2
votes
2answers
35 views

How to calculate the intersection within the grid and saving to the grid

Here is my example: (1) I creat the grid line layer using MMQGIS plugin (2) I use line intersection function to get the intersection points. I want to calculate the distance sum within each ...
0
votes
1answer
29 views

Polygon Representation from Contours

I have contours lines along with their elevations in ArcGIS. I want to create a polygon representation from those contour lines. How can i create polygons from those contours which may help me to ...
3
votes
1answer
68 views

How to reshape polygons with curves in ArcMap?

I'm looking for a good method for reshaping parcel polygons that have curves. One side of a given polygon (like in my screenshot) has a curve but for some reason, the other side was made with straight ...
4
votes
2answers
717 views

Displaying adjacent polygon lines beside each other instead of overlapping

I would like to display adjacent polygons with the line work beside each other, not one on top of the other for that shared boundary. I do not want to edit the polygon boundaries - only want to ...
3
votes
1answer
287 views

Dynamically drawing a polygon around another shapefile, ArcGIS 10.2

Let's say I have a vegetation raster that indicates the density of forest all over the world. I also have a shapefile that contains the admin boundaries of each country in the world. The easy part is ...
9
votes
4answers
3k views

Finding centrelines from polygons in QGIS?

I was wondering if there is a way to create centre lines from polygons in QGIS? I have a polygon layer, but ideally need the centrelines as a separate file.
5
votes
2answers
858 views

How to create zip code areas from point data?

I have a point dataset which has zipcodes for a certain region. This zipcodes have been marked on the basis of lat long collected. So each zipcode is repeated as it would be useful to show the region ...
2
votes
3answers
181 views

Error in merging 2 shape files of different geometry types

I am trying to merge two shape files ... Here are the links of two shape files Australian State & Territory State and Territory ASGC Ed 2011 Digital Boundaries in ESRI Shapefile Format ...
1
vote
1answer
82 views

Get all points with in some range of a point (or range of point) in MySQL

I have got a list of points and a fixed range (10m). So what I have to do is for each point I have to find all the points present in a table with the 10m range of the given point. For example: Let ...
0
votes
2answers
50 views

How to create circles starting with points and attributes (diameter, lat/long)?

I have a point shapefile with attributes (diameter, latitude and longitude). For each point in that file, I want to create a polygon (circle) described by those attributes. The new shapefile should ...
3
votes
2answers
60 views

Move leaflet polygon to given position

I have a circle and a polygon that I'd like to move to the user's local position. I managed to move the circle latLng but I can't find a way to do the same thing with a polygon. Can someone help me ...
2
votes
2answers
225 views

gDistance to determine closest point to polygon: does changing projection change results qualitatively?

I'm using gDistance from the rgeos package for R to find the nearest point to a polygon. The projection of both points and the polygon is +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 ...
4
votes
5answers
2k views

Simplify shapefile parcel layer

I have a very large shapefile with over a million parcels within it. The problem I am having is that the polygons representing each parcel are very jagged. What I am looking for is a simple and fast ...
4
votes
2answers
57 views

Get the 2 points immediately before and after a given point in PostGIS

In the picture below: The given point is C, I would like to select A and B, but not Z (which is closer to C than B but it's not immediately after in the LineString). Note that C is always ON the line ...
1
vote
1answer
80 views

How to properly draw and label overlapping polygons?

I would like to show overlapping polygons on a single layer. The polygons are coloured based on a property and labelled according to another property. The problem is then twofold: The polygons are ...