[postgis-users] tile size

[Duncan Golicher]

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 <Pierre.Racine at sbf.ulaval.ca
> 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: postgis-users-bounces at lists.osgeo.org [mailto:postgis-users-
> > bounces at lists.osgeo.org] On Behalf Of Stephen Crawford
> > Sent: Friday, September 13, 2013 12:34 PM
> > To: postgis-users at lists.osgeo.org
> > 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
> > <dustymugs at gmail.com> 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
> > <src176 at psu.edu> 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>
> >
> >
> >
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> >
> >
> >
> >
> >
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> >
> > --
> > Stephen Crawford
> > Center for Environmental Informatics
> > The Pennsylvania State University
> > src176 at psu.edu
> > 814.865.9905
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-- 
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

dgolicher at bournemouth.ac.uk
dgoliche at ecosur.mx

Researcher ID:
http://www.researcherid.com/rid/B-4240-2009
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