[postgis-users] Postgis Simplify

Markus Schaber schabi at logix-tt.com
Mon Aug 8 01:47:09 PDT 2005


Hi, Christo,

Christo Du Preez wrote:
> Sorry for being stupid but if my data is in [lat/lon wgs84], what should
> I do to Simplify it as much as possible and also for the result to be in
> [lat/lon wgs84]?

First, you need to know how much detail you need in your map.

A good start value is to get the scale in map units per pixel (in your
example degree per pixel if you use no projection).

When using the Douglas Peuker algorithm (which is implemented in
simplify()), you can usually multiply this value with 2 or 3 and use
this as threshold for simplify().

HTH,
Markus




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