[OSGeo-Discuss] Re: idea for an OSGeo project -- a new, open data format

Robert Bray rbray at robertbray.net
Tue Nov 13 23:18:42 PST 2007

A little clarification on SDF, since it comes up once or twice in this 
thread. Jason's earlier descriptions of it's capabilities are pretty good. 
It supports multiple Feature Classes / Tables per file, strongly typed 
properties, multiple geometry properties per class, with seperate R-Trees 
for each geometry property. All of this is stored in a single file that is 
heavily optimized for spatial reads. The SDF FDO Provider suppports a 
multiple reader / single writer model. The geometries themselves include 
simple features + circular arcs in 2D, 2D with Z, 2D with M, or 2D with Z & 
M. The R-Trees are currently 2D.

Is it an open format?  ABSOLUTELY (we just never wrote a spec, but I am 
willing to get it done)

Another little known fact is that in the process of creating SDF we 
(Autodesk) literally wrote the code three times. The first time we built SDF 
on BerkleyDB, a great open source project but it has some fairly significant 
license fees for using it in a proprietary product. The second time we wrote 
it on SQLite, however the performance penalaty of the Relational layer was 
significant (read orders of magnitude). The third time we chose to strip 
away the SQLite relational layer and built directly on the SQLite Backend 
components (B-Tree, Pager, and OS Interface). In the end the third 
implementation actually turned out to be faster than BDB and is the one we 
use today.

All this said, I'd really like to understand everyones requirements for this 
new format. If SDF fits thats great, if not thats ok too. We are always 
happy to contribute what we can to the community.


----- Original Message ----- 
From: "Michael P. Gerlek" <mpg at lizardtech.com>
To: <punkish at eidesis.org>; "OSGeo Discussions" <discuss at lists.osgeo.org>; 
<bitner at gyttja.org>
Sent: Tuesday, November 13, 2007 12:23 PM
Subject: RE: [OSGeo-Discuss] Re: idea for an OSGeo project -- a new,open 
data format

>> > Regarding the suggestion that MapServer takes on this new format as
> the
>> > primary format:  I think this is way beyond the scope of what OSGeo
> should
>> > be doing.
> I agree with bitnerd.  If the MapServer team thinks this is a valuable
> and worthwhile format, they will adopt it at some point.  It would not
> be unreasonable for them to step back and see how thing progresses
> before deciding to spend their valuable ergs on it.  The burden is on
> the "OpenShape" people to show the idea is worthwhile and meritorious.
> (My two cents on the "standards" question: OSGeo is not a standards
> organization, but / however / on the other hand / nonetheless one of the
> reasons OSGeo exists is to foster such collaborations.  If some people
> want to try and develop something new like this, I'm all in favor of
> OSGeo offering mailing list and wiki space to help out.  Declaring this
> to be a "standard" effort, however, is probably premature in any case --
> more useful at this point to see the idea sketched out further, see
> who's interested, etc.)
> -mpg
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