lat/long as float

• From: Mike Dean <mdean@bbn.com>
• Date: Wed, 19 Jul 2006 10:44:59 -0400
• To: <public-xg-geo@w3.org>
• Message-ID: <020801c6ab41$e94dc5d0$0a1510ac@mdeand800>

[1] notes that "the string representation of lat and long should follow the
rules for XML Schema float".  I'm a bit concerned about this, since the
precision of xsd:float is limited to 24 bits (including the hidden bit).  In
the worst case at the equator 

  24000 miles * 5280 feet/mile / (2^24) = 7.553 feet

which is achievable by current handheld GPS units using WAAS, not to mention
differential GPS.

I generally represent lat/long's using xsd:double.  An alternative may be to
specify xsd:decimal and let applications worry about the precision.

I'd prefer to see explicit rdfs:range's for these properties.  The syntactic
burden for datatyping individual Literal values is an unfortunate feature of
RDF.

For clarity, the spec and property definitions should also note that North
latitudes and East longitudes use positive values.

	Mike

[1] http://www.w3.org/2003/01/geo/

Received on Wednesday, 19 July 2006 14:45:08 UTC