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

Stephen Woodbridge woodbri at swoodbridge.com
Sat Nov 12 20:01:59 PST 2016


Thanks, that is good to know.
-Steve

On 11/12/2016 8:24 PM, Paul Ramsey wrote:
> For both curves and for geography the bounding box/volume is calculated
> to take in the whole arc, even if the furthest extent of the arc does
> not happen to have any vertices on it. So, if you density the
> arc/great-circle, the box should not need to be re-calculated, since any
> new vertices will be added into the existing arc.
>
> On Sat, Nov 12, 2016 at 6:35 AM, Sandro Santilli <strk at kbt.io
> <mailto:strk at kbt.io>> wrote:
>
>     On Sat, Nov 12, 2016 at 09:25:58AM -0500, Stephen Woodbridge wrote:
>
>     > What about curved geometries? like arc segments. Is the BBOX defined based
>     > on the true arc BBOX or the segmentized arc BBOX, if the later then changing
>     > the segmentation of an arc could in theory change hte BBOX.
>
>     Yep, this is similar to the point raised by Darafei (geography).
>     To be honest I don't know how BBOX is computed for curves though.
>
>     Once again though, topology does not support curves (nor geographies).
>
>     --strk;
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