[postgis-users] simplify() on lat/lon data

[Paul Ramsey]

If you have lat/lon data, the unit of interest is the "degree", so 0.01 
is still a *huge* distance. You really are best off only using 
simplify() in planar projections. Using lat/lon as a planar projection 
gets bad because the "distance" of X units horizontally is not the same 
as the "distance" of X units vertically.

Tyler Mitchell wrote:

> Folks, I've successfully used (and understood) the results of the 
> simplify() function on my UTM data.  But now I've got some DMS data
> and am stumped - any suggestions on how to make useful data?  I used
> tolerance of 0.01 and my data looks really weird.
> 
> Anyone have recommendations on simplifying this data?  With UTM I 
> understood fairly clearly that my tolerance was in meters, but what
> should I be using in DMS?


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      | Paul Ramsey
      | Refractions Research
      | Email: pramsey at refractions.net
      | Phone: (250) 885-0632
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