[gdal-dev] Map Caching with GDAL

[marcello ferrero]

Hi Robert,
thanks for the reply.
Maybe I'm wrong, but tilecache and memcached both are server side modules, while I need something for the client side of my application (think about something like google maps mobile).
On the other side GDAL in-memory raster seems to me capable of managing pre-decoded raster buffers that in my case would occupy too much memory. 

That's why I need something that is able to read a png (or jpeg) encoded  buffer from memory as it was a file reading.

Marcello


----- Original Message ----
From: Robert Coup <robert.coup at onetrackmind.co.nz>
To: marcello ferrero <marcello_ferrero at yahoo.com>
Cc: gdal-dev at lists.osgeo.org
Sent: Friday, January 25, 2008 11:14:06 PM
Subject: Re: [gdal-dev] Map Caching with GDAL

On 26/01/2008, marcello ferrero <marcello_ferrero at yahoo.com> wrote:
> in order to implement a map caching mechanism for my application I need to read tiles from a server (for example OpenStreetMap) and keep them in memory to speed up subsequent access to the same tiles once they have been already downloaded from the map server.
> To implement this, I'm going to manage a single indexed (x,y,z) data file where I keep the dump of each .png (or .jpg) file.

TileCache running with memcached could do exactly what you want, or
just memcached on its own.
  http://www.tilecache.org/
  http://www.danga.com/memcached/

> Therefore I need to access the .png (or .jpg) tile not from a file (in that case I would simply use GDALOpen to open it), but from a memory buffer.
>
> What are the GDAL functions to do what I need?

Have a look at the in-memory raster documentation:
http://gdal.org/frmt_mem.html

Rob :)


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