[talk-ph] better ways to coordinate coastline mapping?

Jim Morgan jim at datalude.com
Tue Jul 6 07:42:24 BST 2010


Eugene Alvin Villar wrote, On Tuesday, 06 July, 2010 11:57 AM:
> To clarify things, the sawtooth detection script is quite naive. It
> simply detects if there are at three or more series of nodes where each
> pair of adjacent nodes have the same latitude or longitude. This will
> also detect any three linear nodes that all have the same latitude or
> longitude like this: o----o----o  

There are a number of cases where a near-straight line is acceptable. Maybe it would be better -- and I'm not sure if this is possible -- to examine, say, a series of three nodes. It would check if the first two have the same lat or long. If they have the same lat, then the second and third points would need the same long; if they have the same long, then the second and third points would need the same lat. Then you'd be correctly identifying the step-fashion jaggies, rather than straight lines. 


To increase certainty, you could make this a series of four, or five points. Again I don't know if this is possible or plausible, but it would seem like a better pattern to look for. Not sure if the formatting will come through but ....


 p1 |_____ p2
          |
          |
       p3 |______  p4
                 |


Jim

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