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| GeoCommunity Mailing List |
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| Mailing List Archives |
| Subject: | Re: [gislist] Finding Islands on Lakes / topology (?) question |
| Date: |
06/16/2004 09:00:03 AM |
| From: |
John D. Evans |
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Hello Brian,
You wrote:
>(...) What I would like is to be able to assign some sort of code based
>on how 'deep' the nesting is.
>
>For example,
>0 = Not in a region
>1 = Encapsulated by one polygon (e.g. an island in the ocean)
>2 = Encapsulated by two polygons (e.g. a lake on said island)
>3 = Encapsulated by three polygons (e.g. an island on the lake on the island)
>....
>n
>
>I have no idea what n is, but I doubt it's higher than 3-4.
>
>
FYI ... there are real-life examples with n=5:
Treasure Island is in Mindemoya Lake which is in Manitoulin Island which
is in Lake Huron/Georgian Bay which is in the continent of North America.
See http://freespace.virgin.net/john.cletheroe/usa_can/on/manit.htm
Here's a map: http://www.manitoulinproperty.com/map.htm
<http://www.manitoulinproperty.com/home.htm>
[click twice and you can (barely) read "Treasure Island"]
I visited there once while on business in Toronto. (How could I pass up
such a topological oddity)
--
John D. Evans, Ph.D. <john.evans@gsfc.nasa.gov>
NASA Geospatial Interoperability Office / GST, Inc.
1-301-286-0803 / 1-240-542-1133
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