[postgis-users] How to check if two linestring are near to each other

[Raghavan Krishnasamylakshmanaperumal]

Hi Åsmund,

Thanks for suggesting ST_HausdorffDistance, I tried this function directly
on the database using sql query and it looks like solving my problem.

Are these functions ST_HausdorffDistance/ST_Distance available as java
APIs? I am trying to use org.postgis(postgis-jdbc-1.3.1.jar) library but
not sure how to access the above mentioned functions using java. Please
suggest me which package to look into to make use of these functions
programmatically?

Thanks in advance.

-Raghavan


On Sun, Apr 13, 2014 at 1:45 PM, Åsmund Tokheim <asmundto at gmail.com> wrote:

> Hi
>
> I think you should be able to use hausdorff distance
> http://postgis.net/docs/ST_HausdorffDistance.html to recognize that the
> green, red and blue lines in your image are all similar. This method will
> fail to recognize shared portions of a path (e.g. if the blue line at some
> point diverges from the red and green line), but I'm not sure if this is a
> requirement for your task
>
> Åsmund
>
>
> On Sat, Apr 12, 2014 at 9:41 PM, Raghavan Krishnasamylakshmanaperumal <
> rkrish20 at uic.edu> wrote:
>
>> Hi,
>>
>> I have formed a graph using my GPS traces of running/biking activities in
>> which I have many edges representing the same path. For example every time
>> I run from node-A to node-B my GPS traces are noted close to each other
>> like the red,green,blue lines in the attached image. Actually those 3 lines
>> are same(representing the same path), so I want to detect such linestrings
>> automatically and keep only one linestring and ignore others. Is there any
>> way in PostGIS which can help me to detect the nearness/closeness of the
>> linestrings?
>>
>> --
>> Thanks and Regards,
>> Raghavan KL
>>
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>
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-- 
Thanks and Regards,
Raghavan KL
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