[postgis-users] Tiles

[Pierre Racine]

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 11:56 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> :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> :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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