[Tilecache] Estimating disk space requirements

[Björn Harrtell]

Well it should be quite simple.. something like this probably, but don't
blame me if it's wrong.
( (maxx-minx)/(units-per-pixel*tilewidth) ) * (
(maxy-miny)/(units-per-pixel*tileheight) )

About image compression you got png and jpeg.. png is best for lines, text
etc. (and transparency) and jpeg is best for photographic imagery. Jpeg is
degrading so you'll have to choose a compression ratio that suits the
purpose, png uses zip-like compression so there is no real reason to not use
highest compression (I think?).You can strip both of these formats from
metadata if you want to make sure the files are as small as possible (might
actually make quite a difference on millions of tiles).

/Björn


On Feb 5, 2008 11:21 PM, David R Robison <drrobison at openroadsconsulting.com>
wrote:

>  Could you give me the formula for calculating the number of tiles? Also,
> do you have any tips about format/compression/metadata? TNX David
>
> Björn Harrtell wrote:
>
> You can calculate the number of tiles exactly (obviously) but the problem
> is the actual tile image sizes will depend on what kind of map you have...
> blank/ocean areas and photographic imagery beeing the most important
> factors. That's why optimizing the image output
> (format/compression/metadata) from your mapserver is quite important. What
> you could do is try to determine what the largest tile image would be and
> use that multiplied number of tiles as the estimated maximum size for the
> cache.
>
> /Björn
>
> On Feb 5, 2008 10:58 PM, David R Robison <
> drrobison at openroadsconsulting.com> wrote:
>
> > Is there a simple formula for estimating the disk space requirements for
> > the tile cache? Thanks, David
> >
> > --
> >
> > David R Robison
> > Open Roads Consulting, Inc.
> > 708 S. Battlefield Blvd., Chesapeake, VA 23322
> > phone: (757) 546-3401
> > e-mail: drrobison at openroadsconsulting.com
> > web: http://openroadsconsulting.com
> > blog: http://therobe.blogspot.com
> > book: http://www.xulonpress.com/book_detail.php?id=2579
> >
> >
> >
> >
> >
> > _______________________________________________
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> > Tilecache at openlayers.org
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> >
>
> ------------------------------
>
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>
> --
>
> David R Robison
> Open Roads Consulting, Inc.
> 708 S. Battlefield Blvd., Chesapeake, VA 23322
> phone: (757) 546-3401
> e-mail: drrobison at openroadsconsulting.com
> web: http://openroadsconsulting.com
> blog: http://therobe.blogspot.com
> book: http://www.xulonpress.com/book_detail.php?id=2579
>
>
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