Geometry Boost List: [ggl] nearest neighbor/segment

Subject: [ggl] nearest neighbor/segment
From: Barend Gehrels (barend)
Date: 2011-08-16 23:24:26

Hi Matt,

Hmm, seems as if this is completely forgotten indeed... Sorry!

OK, I put it on the list again. Coming weeks and weekends are full, so 
it will about begin september (again).

Thanks, Barend

On 15-8-2011 21:40, Matt Anderson wrote:
>
>   Hi Barend,
>
>   Any news on the "nearest neighbor" function?  (see below)
>
>   Or alternatively is there a way to get this information from the 
> intersect algorithm? (which I have to run anyways...)
>
>   thanks,
>
>   Matt
>
> --------------------------------------------------------------------------- 
>
> http://relativity.phys.lsu.edu/~matt/
>
> On Fri, 10 Sep 2010, Barend Gehrels wrote:
>
>> hi Matt,
>>
>> Welcome to the list.
>>
>>>
>>>   When a point is found to be within a polygon, is there a GGL 
>>> method already in place to find the polygon segment and 
>>> corresponding anchor nodes closest to that point within the polygon?
>>>
>>> [...]  Does a method similar to above illustrated 'unkown_method' 
>>> exist which would return the nodes in question?
>>>
>>>
>>
>> I once created a "nearest_neighbor" function which calculates exactly 
>> this point. Because it was in draft and not completely finished, I 
>> didn't add it yet. For this function it is not important if it lies 
>> inside or outside, and can be used for a linestring, or even 
>> multi-point, as well.
>> I was not sure about the name, and I believe in PostGIS it is called 
>> ST_ClosestPoint, which is better. But (AFAIK) in PostGIS it will 
>> return zero for a point within a polygon, so it is not completely 
>> similar. So if anyone has a suggestion for the best name, it is welcome.
>>
>> I'll try to add it next weekend to the sandbox.
>>
>> Regards, Barend
>>
>>
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>>
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-- 
Barend Gehrels
http://about.me/barendgehrels