[postgis-devel] please review my assumption about segmentize and bbox

[Darafei "Komяpa" Praliaskouski]

ST_Extent('SRID=4326;LINESTRING(-73 40, 53 27)'::geography::geometry) = BOX(-73
27,53 40)
ST_Extent(ST_Segmentize('SRID=4326;LINESTRING(-73 40, 53
27)'::geography,100)::geometry) = BOX(-73 27,53 56.2529232769426)


In planar geometry your assumption should be valid, though.

сб, 12 нояб. 2016 г. в 14:12, Sandro Santilli <strk at kbt.io>:

> Doing topology loading tests I found time is spent to update
> the bounding box of faces whenever their edges are split.
> Following the train of thougths I arrived at asking myself:
>
> Is it possible that adding vertices in a segment could ever change
> the segment bounding box ?
>
> My answer is NO.
>
> Could you please review and confirm ?
>
> If my answer is correct, not only we can speed up topology loading,
> but also (for example) the ST_Segmentize function, which is currently
> *dropping* a cached BBOX value to be on the safe side (ie: to not
> answer that question).
>
> Math proofs welcome :)
>
> --strk;
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