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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8
votes
3answers
367 views

Find Duplicate Polygons Algorithm

I have a group of polygons. My objective is to find the duplicate polygons from these group of polygons. Using NetTopologySuite(A c# port of JTS), it is possible to compare two geometires and check ...
2
votes
1answer
273 views

Software for building non-overlapping sets of polygons?

We have multiple populations of patients spread out over geographic distances. For each population, we want users to easily define non-overlapping polygons. The outer borders are likely to be U.S ...
1
vote
1answer
469 views

How to convert a polygon to a grid of polygons using QGIS?

For example, the city of Rotterdam represented as a hexagonal grid.
3
votes
2answers
627 views

Merging polygons that intersect by more than a specified amount

I am working with a dataset that contains a subset of property boundaries in a local government area, thus my dataset is made up of several thousand properties but not all are touching. Since it is a ...
1
vote
3answers
466 views

How to calculate forest area of a bitmap (jpeg) map?

I have a map of 1:50,000 scale map in .jpg format. Can i calculate the land area of forest,lakes etc from arcmap.Anybody can give me the step to do it? And I want to know what is the coordinate ...
5
votes
2answers
1k views

How to smooth large vector polygons from Raster

I have a landuse classification raster file (6 classes) of a large area. But I need it in vector polygons so I vectorised it. No problem so far, but the result is - of course - that every pixel is ...
3
votes
2answers
2k views

How to perform spatial queries on polygons in mongodb?

I will build a GIS system based on polygons, not just points. I wanted to use mongodb or postgis. how do this in mongodb? Query A - get the center of a polygon Query B - distance between two ...
3
votes
2answers
109 views

Selecting proper polygon

Currently doing a final project for school on ARCMAP 10. I have a set of unsuitable and suitable buffers over a big area which is Quebec City, Canada. The final potential sites give me areas between ...
0
votes
0answers
18 views

World country borders in polygon geometry format [duplicate]

Possible Duplicate: Where do I get territories data? Is there some source I can get all world countries polygon geometry points with latitude and longitude? I find it for USA states but ...
3
votes
3answers
968 views

How to digitize polygons from georeferenced raster file

I used QGIS to georeference a raster file of a custom US map. The map has features which are not strictly defined by state borders. I would like to digitize the map by creating contiguous borders for ...
2
votes
0answers
459 views

cant find point/polygon intersect using qgis (windows only)

below i describe the method i am using. i have 2 machines: 1 ubuntu linux, qgis 1.4 - intersection works 2 WIN xp, qgis 1.8 - intersection dows not work hopefully, someone will ...
1
vote
3answers
2k views

How can I aggregate points to polygons?

I am trying to aggregate my data points to the polygons so that I could find out how many points I actually have in each polygon, and then export the data contained within each polygon to further look ...
3
votes
0answers
178 views

Area-weighted rasterising of polygon data

I'm looking for any GIS tool to do detailed rasterising of polygons. I've checked GDAL's gdal_rasterize command (and API), and ArcGIS's Polygon to Raster tool, but they only rasterise 1 attribute per ...
2
votes
0answers
611 views

How to calculate the area of a polygon considering the relief?

I work in a fire department and i'm mapping all the fires that occur in my area, creating polygons that represent burnt areas. my problem is that the values are not accurate... for instance, arcgis ...
15
votes
5answers
1k views

Algorithm to fix topological errors in GIS software apps

Related question here. I notice that ensuring topological correctness is essential for GIS applications, this is because the input from user or polygon boolean operation can have severe topological ...
0
votes
1answer
382 views

table of polygon centroids

Given a polygon layer, census tracts, how can I generate a table of centroid coordinates in QGIS, or add columns with the centroid coordinates or generate a new layer of polygon centroid points?
3
votes
2answers
1k views

How to change the vertex style for editing?

When I use drag feature, then the circles on the polygon edge has the same style. For example, this OpenLayers site. I need to change it, I mean they need to be a different color. What is their ...
4
votes
0answers
85 views

Reducing Polygons [closed]

I am merging several data sources into one final answer via a fishnet. My problem is I have landcoverage with multiple attributes unioned to a fishnet. Now I want to eliminate the smaller polygons ...
4
votes
3answers
723 views

How to split features?

I would like to split a shapefile in qgis according to how the polygons overlaps. Don't know how to though? See pic for explanation:
1
vote
1answer
168 views

What is the Quickest Way to Update Polygon Geometries in ArcGIS

I have a shapefile which contains the approximate boundaries for sites that are being worked on (thousands) in polygons, each with a reference number and additional detail in the attribution. I have ...
5
votes
1answer
504 views

Identify Polygons on raster image

I have OS street view mapping as raster images. Is it possible (without the obvious of tracing each dwelling) to identify all polygons on each tile. To clarify, My ultimate aim is to produce a ...
5
votes
1answer
1k views

Copy a polygon geometry in Arcpy

This to me sounded very simple so I am probably missing something basic here. What I need to do is to create a copy of a polygon shapefile to a new shapefile with slightly different attributes. Where ...
3
votes
2answers
895 views

How can i select a polygon in MS SQL 2008

I am very new to MS SQL 2008. I got a task to select a polygon from the polygon layer by giving the X-Y coordinates. I already got the script for PostgreSQL for the same thing, but i need it for MS ...
1
vote
1answer
190 views

How to identify Polygon within another Polygon layer

I have two polygons files. The first one has several smaller polygons within it eg.a shapefile with all US states, the other polygon file has a single polygon eg. a river basin. I am trying to get all ...
-1
votes
1answer
209 views

Finding the area of a polygon feature in a shapefile [closed]

Excuse the very simple question. How do i find the area of a selected polygon feature in a shapefile?
0
votes
1answer
319 views

To get attribute data of polygon layer by giving Lat/Lon

Is anyone having an idea about how to get attribute data of a polygon layer by giving Coordinates with in that polygon. Here i have tried with these codes.. SELECT * FROM kar_bbmp_198 WHERE ...
2
votes
1answer
418 views

How to meassure the length of common edges between polygons?

I have a shapefile that contains several polygons which in fact represent the limits of several counties. My task is to find each length of each shared border. So in other words I want to know how ...
3
votes
1answer
335 views

QGIS Polygon layer table of adjacent polygons

In a polygon layer, how can I generate a table of adjacent polygons?
8
votes
3answers
954 views

Creating regularly spaced, defined # of points within polygon in QGIS

I used the research tool "Regular Points" to produce a certain number of points within a polygon, but it forms a rectangular grid of points rather than only within the shape of the polygon. Since I ...
3
votes
0answers
56 views

Passing attributes to neighbouring polygons

I have an ecosystem polygon layer that has been updated using a more recent tree cover layer (to remove cleared areas and also to re-align veg boundaries where growth has occured). Where the polygons ...
0
votes
2answers
644 views

How can I convert Polygon to LinearRing Geometry?

How can one convert a Polygon to LinearRing geometry using OpenLayers? I'm thinking that I can do this by getting bounds of the polygon, then use this to construct a Points array. Finally, use ...
2
votes
3answers
506 views

Split polygon with holes to get several hole-less polygons

Unlike this thread I actually need to split the polygons into several hole-less polygons. I'm not sure on how to approach to this problem. I have polygons with holes of many diferent shapes, like ...
2
votes
0answers
171 views

Polygons of Land Use Change

I am doing a project where I am digitizing a map of Haiti from the 70s. Through R2V I digitized the lines and then I exported it into ArcGIS 10. I am just interested in the land use change, therefore, ...
10
votes
1answer
486 views

How to convert fake donut holes in polygons to real ones?

I have this problem where I have to import shapefiles into our system which must be geometrically valid, but the software that everyone uses to produce them seems to output files where every polygon ...
2
votes
2answers
391 views

Selecting Part of a Polygon

I have a dataset, in shapefile format, for agricultural land grades in England. It is divided into 7 categories in its attribute table. As the file is a large file and I only want a small section I ...
3
votes
2answers
283 views

How to select polygon features that have their centers outside of another polygon feature class

Since I only have Incorporated area feature class, how can I select census blocks that are in unincorporated area? Or not within any incorporated areas? Thank you. John
5
votes
2answers
2k views

How to disable polygon Label on the vertices (OpenLayers) in Edit Mode

I added the style on the polygon layer like so. var style = $.extend(true, {}, OpenLayers.Feature.Vector.style['default']); // get a copy of the default style style.label = "1233456 ha" ...
0
votes
2answers
258 views

How to retrieve a single polygon from a multipolygon layer in GeoServer

I have a multipolygon layer in GeoServer. The layer represents states within a country. I want to enable a user to search for a specific state, and then only the selected state to be displayed on the ...
5
votes
1answer
3k views

can I extract overlap of polygons within the same layer?

I am trying to extract the overlap of polygons that are within the same layer in 10. The layer came from a buffered street centerline and I'm trying to extract and delete the intersections from the ...
2
votes
2answers
347 views

count features in polygon shapefile A that fall within each feature of polygon shapefile B

I have two polygon shapefiles, each of which contain multiple (possibly overlapping) polygons. Is there some way, using GRASS, to calculate the number of polygons belonging to shapefile A that fall ...
0
votes
2answers
1k views

Calculating shape perimeter/area per zone in ArcGis 10

How can I calculate geometrical features of polygon (perimeter and area) per zone (similar to zonal stats for rasters)? I have a square fishnet (approx 20x35, 1 square kilometer each) and I need to ...
2
votes
1answer
291 views

determine whether a circle intersects a county boundary in postGIS

I'm using PostGIS 2.0.1 and need to determine whether a circle (center + radius) intersects a county boundary (polygon). The query I'm using is this: SELECT DISTINCT(u.id) FROM siteareas_poly sa, ...
19
votes
3answers
1k views

Packing Polygons within polygon

I have a Boolean raster. In the grey areas of the raster I would like to fit a given size polygon within a contiguous extent. Basically, I have an irregular polygon, and i would like to "fit" a ...
5
votes
1answer
894 views

finding the long axis of an irregular polygon

Hi need some help in how to find the long axis of an irregular shaped ellipse using ArcGIS. I have found the centroid but don't know how to determine the longest distance.
2
votes
2answers
414 views

FME Donut Hole Extractor

I am using FME to fill in some small holes within polygons. I have used DonutHoleExtractor to split these out, however I have found the output via the HOLE port also brings existing 'filled' holes ...
3
votes
2answers
689 views

Generate non-overlapping shapes from a buffer

I have a collection of points, and I need to generate shapes around these points. Let's assume that these points are locations of offices and that the shapes are the 'area of responsibility' around ...
4
votes
1answer
303 views

Sub-dividing a polygon into smaller polygons

In OpenStreetMap data, some large areas are tagged with a residential=yes tag. Actually within this large polygon there are multiple smaller (rectangular) houses (which are actually not drawn as yet). ...
5
votes
3answers
841 views

How to identify feature vertices that are part of a donut hole in ArcGIS 10?

I´m exporting the coordinates of polygon vertices to a CSV-File using the "Feature Vertices to Points" and then the "Export feature attributes to ASCII"-tools. Some of these polygons have holes ...
3
votes
1answer
517 views

how do I get the “outer mantle” of a polygon shape file? (without joining all the polygons)

I am interested in finding all the vertices of all polygons which are not on the inside the most outer polygoin that can be formed in a shape file: Here is how I get all the vertices: def ...
9
votes
2answers
2k views

Intersecting a raster with a polygon using PostGIS - artefact error

I'm using PostGIS2.0 to do some raster/polygon intersections. I'm having difficulty understanding which operation I should use, and what the quickest way of performing this is. My problem is as ...