New archive file format (was: [omgps] collect feature requests)

Dr. H. Nikolaus Schaller hns at
Thu Jul 2 10:37:30 CEST 2009

I do not completely understand the reasons why there is a need for  
(once again) a new file format.
As far as I understand the proposal, it is just a file system running  
in an image file. Like mounting an ISO or any other file system  
residing not on a raw disk but within a file.

So what problem does it solve better than just using the existing file  
system hierarchy directly (/tiles/z/y/x.png)? If it does not compress,  
has no directories, is not faster and is not more reliable as William  
pointed out.
I see only one benefit - you can copy the whole archive as a single  
object instead of copying a file tree.

New file formats usually create more problems than they solve...

Am 02.07.2009 um 10:08 schrieb William Kenworthy:

> I hope not - I have over 2 million tiles stored on SD card - if file
> corruption or disaster occurs, it may affect only one tile if its  
> being
> accessed at the time - imagine the effect of file system corruption on
> one large archive ... you will most likely lose the lot.
> Then there is the extra overhead needed - Ive gotta ask "why"? - if  
> you
> can justify the extra cpu needed for this, why not do vector maps?
> BillK
> On Thu, 2009-07-02 at 00:42 -0700, mqy wrote:
>> x and y are tile no in tile coordinate system within range of [0..  
>> 2^zoom).
>> just do it if you have time, since proof of concept is necessary :)  
>> keep in
>> mind clear APIs.
>> it's likely that, the final version to be integrated into omgps is  
>> rewritten
>> in C.
>> Laszlo KREKACS wrote:
>>> If I understand right the OSM tiles, they have the following  
>>> directory
>>> ...
> -- 
> William Kenworthy <billk at>
> Home in Perth!
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