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
votes
2answers
427 views

Need an Algorithm to Determining Polygon Borders

I'm currently writing a program in Java and I'm dealing with polygon objects. I want to create a different color border between touching objects depending on their class (i.e. land, ocean, etc). I ...
1
vote
3answers
3k views

How to auto fill or delete sliver polygons without losing precision?

I am developing some boundaries in which precision holds the key value. Using ArcGIS 9.3 I am converting lines to polygons using the "feature to polygon" tool. The lines are accurate but I find ...
11
votes
2answers
5k views

How to check Topology in QGIS?

I have two Shapefiles with Polygons ( City and Forerst) Is there a Plugin who is able check the topology (QGIS)? Like "Knots do not overlap" or something like that? I dont want that they overlap. ...
4
votes
5answers
964 views

Python loop Polygon to raster not working

I want to convert a large number of different shp polygons to raster in ArcGIS 10.1, using an existing field column "class" for the new raster classes. I am not very fluent in python but I thought ...
1
vote
1answer
1k views

arcpy points in polygon check

I have a list of points and a list of polygons both in a separate shape files. I am trying to write a ArcPy script to loop through the points, and then the polygons respectively and tell me when a ...
4
votes
4answers
2k views

Remove Polygon Islands

I'm really stumped with the problem. I have a polygon layer with no intersects or holes and I need to remove some 'islands', as defined by attributes of a certain size within the layer. It's a hard ...
3
votes
2answers
2k views

How to create a multipart polygon?

I have two polygons that consist of two separate polygons/lines in QGIS). How can I make this into a multipart polygon, which consists of 1 line in QGIS?
9
votes
1answer
600 views

Compare spatial cluster/agglomeration patterns for polygon data

I have agricultural data in form of polygons which I would like to test for spatial clusterings/spatial agglomerations. All in all I have about 40 variables which I can aggregate and standardize in ...
11
votes
3answers
4k views

How to merge two Polygons in OpenLayers?

I have two polygons. polygon1 = new OpenLayers.Feature.Vector(new OpenLayers.Geometry.Polygon([linearRing1])) polygon2 = new OpenLayers.Feature.Vector(new OpenLayers.Geometry.Polygon([linearRing2])) ...
4
votes
1answer
6k views

How do i calculate line segment lengths within a polygon?

I have a layer with line segments and a layer of polygons (in this case, buffers around points). I need to create a new field for each polygon that contains the total length of all line segments ...
0
votes
1answer
826 views

Geojson multipolygon doesn't work with Leaflet bindPopup?

I have polygon and multipolygon data in Geojson format and when I try to bind popup for polygon, it works perfectly, and when I try to bind it for multipolygon, it doesn't work. Is that some Leaflet ...
1
vote
0answers
32 views

Suggestions for vector format for polygons

I am using two polygon tables in postgis (A and B ). I need to make a vector file that incorporates information of the overlapped polygons B intersecting each polygon on (A). I can make a single ...
1
vote
0answers
68 views

When digitizing, objects are not saved well

I've some problems with digitizing. If I draw a line or a polygon, the line or polygon is saved in the attribute list, but not visible and its location is not saved either (when I zoom to the object ...
0
votes
1answer
3k views

Calculate maximum and minimum elevation for a polygon layer from a DEM [duplicate]

I have a polygon layer and would like to know the min and max elevation within each polygon. My elevation layer is a digital elevation model. I'm not quite sure how to extract that information. I am ...
1
vote
3answers
7k views

Understanding the polygon handler function in Openlayers

Using openlayers, I want to be able to draw one polygon on a map. After one polygon is drawn, I want an event to fire that stops any more from being drawn until a button is pressed. My current code ...
0
votes
0answers
158 views

Where can I get polygons for the Municipalities of Puerto Rico?

I'd like to find GeoJSON files to draw the polygons of municipalities of Puerto Rico. It might be nice get the Nokia Map (or any reasonable publicly available map) of the same regions and overlay ...
3
votes
1answer
1k views

Merging multipolygon data into a polygon

I have a MultiPolygon representation of some shapes in POSTGIS, I am trying to convert them to Polygon data. I tried, st_geometryn(r.geom, 1) but that didnt work because the way polygons are ...
3
votes
1answer
2k views

find polygon corner coordinates

I am trying to get the coordinates of each node of the polygon I create. I would like the attribute table to display the name of the polygon (ex. address) and then the coordinates of the nodes (ex. ...
6
votes
1answer
379 views

Efficiently identifying overlapping polygons with Python

I'm parsing the NOAA severe weather alert feed and using it as a datasource for a weather alerting system. In the feed, I occasionally find a polygon entry for an alert. Unfortunately, counties that ...
1
vote
0answers
55 views

Add regular points to each polygon in QGIS [duplicate]

Possible Duplicate: assign and move centroids to their polygons I'm trying to find out a method to define a unique ID based on specific coordinates for each polygon of a shp. The problem is ...
5
votes
1answer
1k views

Create a new vector layer that fills space between other polygons in QGIS

I inherited a clipped (500m radius) land cover map containing vector layers of different land cover categories such as buildings, grass, roads, etc from a colleague. The empty (white) space in ...
4
votes
3answers
1k views

Python OGR: convert a point geometry into polygon

I'm writing a routine for creating the convex hull envelop around shapefiles of islands. I could read the data, extract polygons vertices into a geometry and then compute the convex hull. Now I need ...
0
votes
2answers
679 views

Adding values to Fishnet Grid?

I have developed a fishnet grid for my study area. I have various datasets for the area and want to allocate a value (from one of the pre-determined datasets) to each polygon within the Fishnet. ...
6
votes
2answers
309 views

Breaking apart a polygon layer by unique values, creating many new layers

I have a large dataset of habitat information that I need to calculate distances from animal locations to the closest polygon of each habitat type. The way to do this, that I understand, would be to ...
6
votes
1answer
330 views

Can you permanently set the polygon/polyline segment length?

I'm trying to create a several hundred polygons in ArcGIS 10, each of which may have up to several hundred vertices. For consistency sake I would like each line segment in these polygons to be of a ...
3
votes
0answers
108 views

Create perimeter from given area [closed]

I need to develop a web-based application to manage areas inside a bigger area. I already have the initial perimeter, and it has irregular borders like that: . I will need to tell the app to ...
1
vote
3answers
600 views

How to create one KML per polygon (from one Shapefile)?

I have a shapefile containing hundreds of polygons. I need to create a kml of each of the polygon. Is there any way that I may not have to deal each polygon individually and my polygon file may give ...
6
votes
2answers
158 views

summing up over an area based on a distance related function

Through a field study, we learned that the density of a bird species in the forest was related to the distance to forest edge: ln(density) = 1.89*(distance to edge) + 0.34 Now, for any forest ...
1
vote
4answers
5k views

Sum of areas in all each polygon layer?

I've got several layers/feature classes in an ArcMap 10 project. Thanks to everyone's help, I'm able to get the areas for the polygons contained within each layer. By opening the attribute tables ...
12
votes
3answers
2k views

Optimizing a nearest neighbor calculation using PostGIS

I'm using PostGIS to calculate the nearest neighbors of polygons. What I want to calculate is the minimum distance from each polygon, to the nearest polygon. Thus far I have got great help from Mike ...
1
vote
0answers
614 views

How to clip the contour map with the polygon using R software?

Hi I am wondering how can I create the contour lines from the discrete x, y and z dataset and then add the shapefile to cut the contour lines by polygon. I want to clip the contour map by the shape ...
5
votes
3answers
2k views

How to interpolate into polygons?

I need to interpolate values from points to polygons. I have a point shapefile and a shapefile of adjacent polygons. Some polygons get several points falling inside, some have nothing. I thought ...
4
votes
3answers
452 views

How to subset X number of features from Shape file in QGIS

I'm looking for a means to take a rather large Shape file and split it out into separate, smaller shapefiles based on number of features. So for example, if I have a file with 1 million features, ...
5
votes
2answers
743 views

How to achieve an “inner glow” effect on polygons drawn using the Google Maps v3 javascript API?

Is it possible to produce an "inner glow" effect on polygons drawn using the Google Map v3 javascript API? If not possible using the vanilla Google Maps API, is there a 3rd party tool that can do it? ...
0
votes
3answers
432 views

Calculate 'Rectangle' Coordinates Given 2 Points and width [closed]

I want to create a rectangular polygon using two points as guides. So let's say a journey starts in Egypt and ends in London, my polygon should have 4 points: 10 miles further from London than Egypt ...
3
votes
1answer
399 views

Qgis analysis on polygon

I have a data table mapped and the table also contains further information of interest, beyond the lat/long of the specific data points. I want to be able to draw a polygon and then simply have a ...
2
votes
1answer
101 views

What is the PostGIS function for retrieving buildings by road side?

I want to get information of buildings by the road side only. Assuming that the building table has multi-polygon geometry and the road table has multi-linestring geometry, what would be a pgSQL Query ...
2
votes
1answer
496 views

How to remove a hole from a polygon in OpenLayers?

Is it possible to remove a hole from a polygon by using OpenLayers? How can I do so?
6
votes
1answer
495 views

Generalize large polygon-file

I have a large polygone file with landuse information (6 classes). Its vectorised from a raster classification so the polygons are all angular. Any of my tries to generalize with v.generalize (sneaks, ...
2
votes
1answer
239 views

Obtain normalized raster average per polygon?

I have a raster that contains percentages of total forest killed plus a polygon layer that defines different zones. My goal is to find a good statistical representative that describes the forest ...
9
votes
3answers
1k views

How to sum up values of neighbouring polygons?

I hope that you can help me with the following problem: I have a vector (polygon) layer. I would like to add an attribute to the layer that - for every polygon - sums the values of a specific field of ...
11
votes
3answers
373 views

How to improve drawn shapes in Quantum-GIS?

I have a polygon-shape in qgis-1.7.0 and want to fix overlays and gaps between the edges of adjacent polygons. See image below. Is there any automated way to do this in quantum-gis? Or any other ...
6
votes
1answer
7k views

How to enable “snapping” in Quantum-GIS while drawing polygons?

I tried to draw polygons in qgis-1.7.0 and I somehow can't find or failed to find the "snapping" option. I'm used to ArcGIS-10.0 where you have some snapping options, like placing points of polygons ...
7
votes
2answers
371 views

How do different GIS systems determine a Polygon's interior?

I'm interested in understanding how real-world GIS systems and their data encode Polygons. Specifically, how do they resolve the ambiguity of a Polygon's interior on a sphere? Background: in 2D, ...
4
votes
0answers
320 views

How to write a script to square polygon corners?

I'm looking for a script that will square the corners of polygons that are near 90 degrees but not exactly. Near could be dealt with via a variable, for example within 5 degrees of 90 (85 - 95 ...
11
votes
4answers
2k views

How to colour polygons with a completely transparent fill using MapServer?

Is it possible to fill polygons so that they are completely transparent in MapServer? I want to have a black background that is slightly opaque, and wherever there is a polygon I want that to be ...
0
votes
1answer
672 views

OpenLayers polygon fill not working with GeoJSON file as source

I'm trying to visualise some data in a custom shape on a map, and I'm stuck with styling it. I'm currently using the openlayers framework in combination with a geoJSON file that I generate in code. ...
2
votes
3answers
336 views

How to calculate exact area of a loaded jpg map in to arcmap?

I calculated the polygon area through arcmap.but i'm not sure that the area is not actual,may be scale is not right. so how to calculate the exact area of a jpg image?
3
votes
2answers
735 views

How to filter out multipart polygons and then buffer?

I've written a small script trying to accomplish the task described in the question title. It basically looks like: in_fc = '...' # Some shapefile goes here # Get the fields (column names) of the ...
1
vote
0answers
35 views

area weighted average for overlapping polygons [duplicate]

Possible Duplicate: How to use NASS county level crop data to estimate crop acreage in hydrologic regions? It seems like an easy problem but I don't know how to go about it. I have two ...