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Re: [Ecrit] Consensus Call: Precise Location Information not available t

Subject: Re: [Ecrit] Consensus Call: Precise Location Information not available to End Host
From: Andrew Newton
Date: Mon, 23 Apr 2007 14:24:39 -0400

On Apr 23, 2007, at 2:04 PM, Henning Schulzrinne wrote:


Holes in that boundary don't affect the centroid-based search. What will happen depends a bit on the way the information is stored. In simple cases, where the PSAPs serving the hole are stored in the same authoritative server (or represented as summaries in those servers), a point that hits that hole will generate two matches: the surrounding-area PSAP and the more specific one. The server can then inspect the holes registered for the surrounding-area PSAP and discover easily that the special-case PSAP for the hole is the right answer. There are optimizations you can do to make this efficient, in particular since the area of the hole is by definition smaller than the surrounding area (without taking the whole into account).

So, how does a server know that the input polygon should match an exact polygon in the db (as is needed for the VSP test) vs a need to find the centroid before looking for a match (as would be needed for regular uses of LoST)? In the first case, the VSP test will fail because it will match the more specific polygon, according to your description above.

-andy

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