Out of interest I quickly checked whether the conclusions still hold for PostGIS2.2. The changes made in ST_Clip, and some other functions including st_value seem to have altered not just the absolute timing (much faster) but also the relative timing of operations as a function of tile size. Point on raster overlays are now slower when tile size is small (<50 pixels), whereas previously there was an almost linear increase with tile size. Bborie may be able to explain why this change has occurred. I will try to add an update to the weblog at some point in order to clarify the sitation. It is GOOD NEWS as apparently there is now a single optimum tile size for both polygon and point overlays and this does seem to lie at around 200 - 300 pixels using the same example as the weblog, although I have not run enough tests to confirm this. I'll try to find time to confirm this.
Duncan On Thu, Sep 19, 2013 at 10:36 AM, Pierre Racine <[email protected] > wrote: > You can also have a look at this article from Duncan Golicher if you are > doing raster/vector analysis: > > > http://duncanjg.wordpress.com/2012/10/30/tile-size-for-raster-vector-overlays-in-postgis/ > > > -----Original Message----- > > From: [email protected] [mailto:postgis-users- > > [email protected]] On Behalf Of Stephen Crawford > > Sent: Friday, September 13, 2013 12:34 PM > > To: [email protected] > > Subject: Re: [postgis-users] tile size > > > > OK, thanks. I will give that a try. > > > > > > > > On 9/13/2013 12:31 PM, Adam Eskreis wrote: > > > > > > The most common tile size that I've seen in production is 256x256 > > > > > > On Fri, Sep 13, 2013 at 10:33 AM, Bborie Park > > <[email protected]> wrote: > > > > > > Steve, > > > > There really isn't. What I do recommend is that if your > raster > > data is not going to change over time (and you don't need to replicate > the > > database), load them as out-db rasters. That way, you can easily change > tile > > size within the database with ST_Tile. > > > > > > > > -bborie > > > > > > On Fri, Sep 13, 2013 at 6:06 AM, Stephen Crawford > > <[email protected]> wrote: > > > > > > Hi All, > > > > Is there a rule of thumb for determining the best > tile > > size when tiling a raster? > > > > Thanks, > > Steve > > > > > > -- > > Stephen Crawford > > Center for Environmental Informatics > > The Pennsylvania State University > > <tel:814.865.9905> > > > > > > > > _______________________________________________ > > postgis-users mailing list > > [email protected] > > http://lists.osgeo.org/cgi- > > bin/mailman/listinfo/postgis-users > > > > > > > > > > > > _______________________________________________ > > postgis-users mailing list > > [email protected] > > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis- > > users > > > > > > > > > > > > > > _______________________________________________ > > postgis-users mailing list > > [email protected] > > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > > > > > > -- > > Stephen Crawford > > Center for Environmental Informatics > > The Pennsylvania State University > > [email protected] > > 814.865.9905 > _______________________________________________ > postgis-users mailing list > [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > -- Dr Duncan Golicher Investigador Titular, El Colegio de la Frontera Sur, Chiapas,Mexico Mexico tel +52 1 967 137 94 20 Skype name duncangolicher Publications: http://www.mendeley.com/profiles/duncan-golicher Senior lecturer, Bournemouth University, UK Centre for Conservation Ecology & Environmental Change School of Applied Sciences Christchurch House rm C218a Bournemouth University Fern Barrow Poole (Dorset) BH12 5BB UK Tel. +44 (0)1202 961682 For list of publications see Researcher ID: http://www.researcherid.com/rid/B-4240-2009 [email protected] [email protected] Researcher ID: http://www.researcherid.com/rid/B-4240-2009
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