[postgis-devel] Proposal: Adding buffer parameter to ST_TileEnvelope()

[Regina Obe]

I assigned Paul, Raul, Sandro, and Darafei for feedback.

 

I don’t have too many opinions about it.  If Raul is fine with it, I’m fine with it :)

 

 

Thanks,

Regina

 

From: postgis-devel [mailto:postgis-devel-bounces at lists.osgeo.org] On Behalf Of Yuri Astrakhan
Sent: Saturday, December 7, 2019 12:42 PM
To: PostGIS Development Discussion <postgis-devel at lists.osgeo.org>
Subject: Re: [postgis-devel] Proposal: Adding buffer parameter to ST_TileEnvelope()

 

What should the next steps be to get https://github.com/postgis/postgis/pull/514 merged?  Are there any blockers or required TODOs?  Thanks!

                                                                                                     

On Thu, Nov 14, 2019 at 2:29 PM Yuri Astrakhan <yuriastrakhan at gmail.com <mailto:yuriastrakhan at gmail.com> > wrote:

How should we grow tiles then with regards to the bounds parameter?  I see two approaches:

* bbox longitude (x) is not clipped unless it grows wider than the bounds, in which case the result spans the whole bounding box. Latitude (y) is always clipped.

    PROs: makes it possible to use with geometry columns without any extra modifications.

    CONs: might cause confusion because the result could be outside of bounds, and because it might not match geometries across antimeredian.

* bbox grows up to the bounds, and then gets clipped.

    PROs: all generated bboxes are within the bounds, using it as filter always matches real data in the geometry columns.

    CONs: have to manually extend it across antimeredian if needed.

 

I'm inclined to go with the first approach, would that be ok?

 

On Thu, Nov 14, 2019 at 7:58 AM Paul Ramsey <pramsey at cleverelephant.ca <mailto:pramsey at cleverelephant.ca> > wrote:

 





On Nov 13, 2019, at 11:35 PM, Yuri Astrakhan <yuriastrakhan at gmail.com <mailto:yuriastrakhan at gmail.com> > wrote:

 

Rough implementation PR - https://github.com/postgis/postgis/pull/514

 

I am having some issues with unit tests (too much magic in auto-generated code?), so a Postgis guru's help might be needed.

 

One open concern: extending envelope beyond antimeredian. Is this possible? Would a bbox from the tile that overflows to the other side of antimeredian match any geometries? For example, given two points - one at -179, and the other is at +179 (longitude), would they be found with the bbox that goes from -200..-160 ?

 

In geometry they would not match, in geography they would.

 

P





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