[postgis-users] Tiles

[Pierre Racine]

All tiles of a same coverage should be stored in the same table. One tile per row.

There is a variant of ST_SummaryStats working on such a table as a whole. You have to pass the name of the table and the name of the raster column.

Pierre

> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-
> bounces at postgis.refractions.net] On Behalf Of Joan
> Sent: Tuesday, November 08, 2011 12:14 PM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] Tiles
> 
> In a case where I use ST_SummaryStats I would like to have statistics of the
> coverage, so I should have the coverage as one tile. Isn't it inconvenient for a
> user to have several tables of the same coverage?
> 
> 
> On 8 November 2011 18:01, Pierre Racine <Pierre.Racine at sbf.ulaval.ca> wrote:
> 
> 
> 	Briefly the ST_Intersection(rast, geom)  vectorize the raster in order to
> make a standard vector/vector intersection afterward. Since vectorizing is a
> slow process, a query involving ST_Intersection() is always more efficient with
> smaller tiles.
> 
> 	Pierre
> 
> 
> 	> -----Original Message-----
> 	> From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-
> users-
> 	> bounces at postgis.refractions.net] On Behalf Of Joan
> 
> 	> Sent: Tuesday, November 08, 2011 11 <tel:2011%2011> :56 AM
> 	> To: PostGIS Users Discussion
> 	> Subject: Re: [postgis-users] Tiles
> 
> 	>
> 	> Yes, I have been doing an analysis with the same raster file but
> different tile sizes
> 	> and I get different results e.g st_intersects(rast, geom) . I would like to
> know
> 	> what the tile size has to do with the query results or performance.
> 	>
> 	>
> 	>
> 
> 	> On 8 November 2011 17 <tel:2011%2017>  <tel:2011%2017> :30,
> Pierre Racine
> 
> 	> <Pierre.Racine at sbf.ulaval.ca> wrote:
> 	>
> 	>
> 	>       I guess you mean "raster tile"?
> 	>
> 	>       > -----Original Message-----
> 	>       > From: postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-
> 	> users-
> 	>       > bounces at postgis.refractions.net] On Behalf Of Joan
> 
> 	>       > Sent: Tuesday, November 08, 2011 10 <tel:2011%2010>
> <tel:2011%2010> :19 AM
> 
> 	>       > To: PostGIS Users Discussion
> 	>       > Subject: [postgis-users] Tiles
> 	>
> 	>       >
> 	>       > Hello,
> 	>       >
> 	>       > I would like to know what the idea behind tiles is.
> 	>       >
> 	>       > Regards
> 	>       >
> 	>       > Joan M
> 	>
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