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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7
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7answers
2k views

Intersection algorithm that correctly handles the 180° meridian and poles?

Is there a well known intersection algorithm that correctly handles 180 meridian and poles? For example, let's say we have a list of latitude and longitude values that represent Antarctica. Let's ...
2
votes
1answer
229 views

Convex Quadrilateral Polygons subdivision in equal parts using Python / OGR

Consider an irregular polygon (P) which has four vertices. I would like to subdivide P into smaller polygons as shown here http://i.stack.imgur.com/4SKhB.jpg In the old days I was using ArcGIS 9.3 ...
2
votes
2answers
144 views

What's the best way to determine if a point is within a certain distance of a GEOJSON polygon?

What's the best way to determine if a point is within a certain distance of a GEOJSON polygon? Should one use TurfJS buffer method (https://github.com/Turfjs/turf-buffer#turf-buffer)? Can one perform ...
0
votes
1answer
53 views

How to select all polygons where neighbor vertex points are below a distance threshold in arcmap

I have a shapefile with over 100k polygons (some of them have holes in them but apart from that they are simple polygons - no multipart). I want to loop through all of these polygons and select only ...
1
vote
2answers
53 views

Moving polygons to points

I have a polygon shapefile that corresponds to a point shapefile in the same projection. I need to move the polygons so that the vertices line up with the points. Right now they are about 3 feet off ...
0
votes
1answer
66 views

How to combine multiple zipcode polygons into one polygon

In CartoDB, we have a table of chapters that make up a national organization. Each chapter record has a polygon that defines the geographical area that the chapter covers. The area a chapter covers ...
4
votes
2answers
305 views

What methods exist for geohash of polygon?

GeoHash is an excellent method to code the latitude and longitude of a point into a string. It's concise, due to the use of numbers + letters, and the precision can be tuned adding characters at the ...
6
votes
0answers
213 views

Group polygon features to match a set of specifications

I have two different sets of polygon features (398 census tracts and 80 ZIP codes) that each roll up to a larger feature (a US county). Though census tracts are smaller than ZIP codes, they do not ...
10
votes
3answers
292 views

From polygon to continuous measure of diversity?

First of all; I have tried to find a similar question, without success. Maybe it's because I'm quite new to GIS and I don't really know what exactly I'm looking for. If someone points me to a similar ...
1
vote
1answer
122 views

Need to quickly know (CLI) whether point lies inside polygon

in my app I am parsing an XML from the web which gives me such coordinate info: I am able to use my app to get a pair of float values like 14.871381 and 50.065968. I do not want any complicate ...
6
votes
1answer
2k views

What is the best way to connect spatial data with attributes in Excel table?

I have many attributes which are stored in an Excel table. They refer to USA counties. I need to somehow connect those attributes to polygons in some format (don't know which is the best) and ...
0
votes
0answers
149 views

Leaflet vs Openlayers vs Geoserver for overlapping polygons application

I have 3 layers of vector polygons(about 80 polygons - 1MB geojson each but I haven't simplified any yet) displaying school territories (kindergardens, primary and secondary education) and I want to ...
5
votes
0answers
96 views

Split polygon by area using ArcGIS for Desktop (or QGIS)? [duplicate]

I'm interested to split a larger, irregular polygon into smaller ones. I know the area of the resulting polygon, and I know that the line I want to split it by should be parallel to one of the sides ...
1
vote
0answers
22 views

How to delete lines that do not overlap a polygon? [duplicate]

I'am new to QGIS and I run into a problem. I have two shapefiles, one with line data and one with polygon data. I would like to remove all the lines that do not overlap the polygon. So remove all ...
0
votes
1answer
33 views

Want to intersect a polygon of a certain elevation with a tin surface

so I want to generate a flood plain for a river in ArcMap. Basically this means that I want to create polygons with certain elevations above the drainage point elevation (870 m). For instance I would ...
1
vote
0answers
51 views

Determining Euclidean Distance in Polygon using ArcGIS for Desktop?

I would like to ask about how to create an euclidean distance analysis from a polygon shapefile. I got a geology shapefile in which I want to create a "distance from geological boundary" analysis. ...
1
vote
1answer
58 views

QGIS how to align existing polygon borders

I'm looking for a method to align the borders of two overlapping and already existing polygon layers. I'm aware of the node tool and its tolerance snapping option, but the area I'm working with is too ...
2
votes
1answer
79 views

Why are a polygon's vertices jumbled after importing KML into MySQL?

This is original KML : <Polygon><outerBoundaryIs><LinearRing><coordinates>104.700355,-3.056064 104.632127,-3.103623 104.608924,-3.103169 104.570166,-3.102411 ...
2
votes
1answer
54 views

QGIS: How to merge single polygons to multi part polygons by maximum distances?

I have a polygon layer with a land-use class and ID for every polygon. How can I merge polygons (into multi part polygon) which do not adjoin, but are not further than x meters apart from each other. ...
2
votes
0answers
87 views

How to merge an excel file with a shapefile in r

I am new to mapping in R so my question might look trivial. I want to have a density map of US for number of phone calls for different areas. Each area includes some zip codes. I only have number of ...
0
votes
1answer
76 views

CartoDB - Multipolygon not showing intersections

I'm having an issue with Multipolygons on CartoDB. I have a very simple scenario: A multi polygon row on a table that needs to be displayed on the map. Fact is that when more than two polygons ...
2
votes
0answers
85 views

Extracting gridded data from polygon vector layer

So I've spent a few enjoyable (and frustrating) days teaching myself the basics of QGIS and fiddling around to try get some data output I need to drive some calculations. Sadly I'm not having any joy ...
1
vote
1answer
40 views

How to convert Geodatabase to open standards to process it further?

I have a ESRI file in geodatabase format (v9.3). I intend to use this in a non-commercial application. I think I will have to convert it into a open standard since I am confused if ArcGIS online would ...
1
vote
1answer
94 views

Why does one polygon disappear when merging in edit mode?

I want to merge some polygons into one using the merge tool. But when doing so, one of the polygons just disappears (see screenshot 2). Why does this happen? When I use the simplify tool before, it ...
0
votes
0answers
23 views

GRASS: How to remove several categories from a geometry?

I am totally new to GRASS (and have found it difficult to get into that way of thinking and its terminology). I use grass70 under Ubuntu 14.04. I have the following problem which I have tried to ...
5
votes
1answer
2k views

How to calculate polygon area considering slopes?

I am looking for an accurate algorithm or a service to calculate surface area on earth where points are calculated on the basis of GPS Coordinates. I am using Google Map Api version 3 and are drawing ...
3
votes
2answers
77 views

QGIS calculates main soil type of polygons from another polygon layer

I've been working with qgis for a while but somehow I never fiured this out, so I thought it's time to ask. I have 2 shapefiles. a polygon layer from nearby fields (SHAPE1 (the red outlines)) a ...
0
votes
1answer
390 views

How to calculate the percentage of distribution in each polygon?

I have binary map for disease suitable area and I want to calculate the percentage using pixel count in each polygon how can I do that? I use zonal histogram and do have frequency for each polygon is ...
2
votes
1answer
27 views

Percentage of a polygon at, or less than, a specific height (supplied by a raster)

I am using QGIS to process some LIDAR data. I need to be able to define the area of a pond with respect to its depth (i.e it is 100m^2 at 32mAOD and 500m^2 at 33mAOD). Is there a way of finding the ...
9
votes
7answers
16k views

Get boundary of raster image as polygon in ArcGIS Desktop?

I have a rectangular raster image in ArcGIS. My question is: how can I produce a polygon which is just the extent of the raster image? That is, I want to have a polygon layer with a single ...
3
votes
0answers
70 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
votes
1answer
235 views

digitizing (tolerence) error in line data

I have designed a large number of boundaries. For accuracy, I took lines in patches from different data sets and merged them into one. Now I want to turn them into polygons from lines. I every second ...
1
vote
1answer
347 views

How to get list of all markers from selected Polygon using OpenLayer MAP v2

I am able to run following features on OpenLayers Map Version 2.x Put Markers on Map Draw Polygon on Map Select Polygon on Map Now my requirement is when i select any polygon then i would like to ...
1
vote
1answer
250 views

GEOS_ERROR: TopologyException: Input geom 1 is invalid: Self-intersection at or near point

I'm using GeoDjango (but I guess this is from the geos library). I have a set of polygons that compose a city surface and I want to merge them into a single one. The code looks like this: polygons = ...
2
votes
2answers
81 views

Mapping Russia - Int'l dateline splitting polygon

I am having the issue where the International Dateline is splitting a polygon I am working with. I have a layer of the "Federal Districts" of Russia, and the eastern most federal district is being ...
3
votes
3answers
3k views

Polygon to Raster Tool Problem

I am trying to create a raster data set from county level polygon data for the US. I have successfully created one raster from a dataset, but when attempting another, it does not work. I am ...
3
votes
1answer
115 views

Shapefiles - Polygon type - is it in fact multipolygon?

I'm wondering about the ESRI shape file with shape type 5. When reading the spec I see that "A polygon may contain multiple outer rings.". Does this mean that these outer rings must be combined to ...
2
votes
1answer
51 views

Intersection between polylines feature to polygon in QGIS

I would like to transform a line shapefile into polygons. However, the tool Vector>Geometry>Line to Polygon doesn'to work to me. What I would like to do is using the intersection between lines and ...
0
votes
1answer
77 views

Is it possible to join points to a polygon in MapInfo Professional v10.0?

This is what I have... ... and I would like to assign the points to the polygons that they belong to. In ArcGIS this is accomplished fairly easy through using Spatial Join, but I have no clue how ...
3
votes
3answers
120 views

Using SVG from Wikipedia to fill polygon?

I'm trying to use the flag of each region in Italy to fill each region's polygon. I have downloaded the shapefile of Administrative areas for Italy from diva-gis and am now attempting to fill each of ...
9
votes
1answer
196 views

Cutting out the world into polygons of equal population size

I would like to cut out the world into polygons of equal population size, say 100 million persons (starting for example with raster data of population density as provided by the NASA). I know that ...
1
vote
1answer
419 views

How to extracting raster data to multiple polygons?

I have a reclassified raster dataset (10 classes) and I want to find out the area of each class contained within multiple (hundreds-to-thousands) polygons. I have all the polygons in the same ...
1
vote
0answers
22 views

How to merge DMAs using QGIS — Creating Custom Regions?

What I am trying to do might seem basic, but bear with me as I am just hacking my way through a lot of this space. What i am trying to do: I am trying to create a new .shp file of custom regions. ...
6
votes
1answer
1k views

Easily calculate “roundness/compactness” of a polygon

I am trying to find ways to quantitatively describe the shapes of various polygons. For my project, these polygons represent lakes, rivers, lagoons, and parks. So they can be almost any shape. One ...
3
votes
1answer
59 views

How to insert some holes in a polygon?

I have a problem with QGIS digitizing advanced tool plugin. I have a landcover-like shapefile. I have to perform some corrections on it, and I have to cut or split some polygons. I want to insert some ...
2
votes
2answers
71 views

Check if a polygon is at one elevation

I have a polygon (pond) and I need to ensure it is at one elevation. I have converted all vertices of the polygon to points, used summary statistics to determine the range in elevations and if the ...
0
votes
0answers
29 views

RasterToPolygon tool is looking inside the output location and not reading the fields

I am trying to convert IMG classified rasters to polygons. I created a code using the Raster to Polygon tool and it worked for 8 of the 50 files; for the rest, I get errors 010157 (Unable to open ...
0
votes
1answer
38 views

largest area polygon

I have a layer of polygon shapes, I know this could be a quite easy question to answer but I am a beginner and probably I am not using the right concept or terminology when looking at the desktop help ...
1
vote
1answer
122 views

Generate territory polygon from sets of points

I'm looking for a simple way to generate contiguous "territories" from sets of points. Say, points A, B and C are in territory 1, and D, E and F are in territory 2, then generate polygons that lie ...
2
votes
1answer
93 views

Convert Layer to Shapefile without losing Feature definitions

I have created a worldmap with custom defined Features, representing State/Zip-Code sales areas. I want to convert them into a Shapefile, so I can convert the Shapefile into a polygon definition file ...