[postgis-devel] ST_Simplify vs ST_SimplifyVW

[Komяpa]

Having different simplification functions is cool thing to play with!

It's strange, however, to get non-simplified output from simplifying
function. 0 as epsilon is commonly used to remove duplicated points or
points on overnoded datasets - I assume that s/Simplify/SimplifyVW/g in my
scripts shouldn't change semantics at all?..

Also consider adding ST_Buffer(ST_Buffer(ST_Buffer(geom, -eps), 2*eps),
-eps) as an option to the list - ST_Simplify for a polygon alone doesn't
make it look good on ultra-low-zoom renderings.



2015-06-03 23:34 GMT+03:00 Paragon Corporation <lr at pcorp.us>:

>
>
>
> > What I think about is if we should have a table also oncluding
> ST_SimplifyPreserveTopology describing the differences, and if so, where in
> the doc should that be?
>
> > Thanks
>
> > Nicklas
>
> I'm just going t opinionate on this one since I haven't thought much about
> the other questions you asked, nor really looked at the differences of
> each.
>
> Yes we should have a table describing the differences.
>
> Since simplification is often used for performance reasons -- e.g. make
> intersects less costly, or for reducing weight sending over the wire, I
> would put the table somewhere in this section:
>
> http://postgis.net/docs/manual-dev/performance_tips.html
>
> Create a whole new section in fact on the topic of simplification
> describing
> use cases, and detailing the different functions (not 4 really if you
> include ST_EffectiveArea)  and how they differ.
>
> Then all the different functions, can link back to the topic in this
> section.
>
>
> Thanks,
> Regina
>
>
>
>
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>



-- 
Darafei "Komяpa" Praliaskouski
OSM BY Team - http://openstreetmap.by/
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