- From: Erik Wilde <dret@berkeley.edu>
- Date: Wed, 25 Jun 2008 10:00:26 -0700
- To: public-geolocation@w3.org
Jon Ferraiolo wrote: > For lay people (such as me) who until now have never heard the term > "geodetic system" before, perhaps the API can have the ability to return > a simple lat/long value but somewhere inside the spec there can be an > explanation of which geodetic system (or whatever the proper term is) is > used by default. it seems that wgs84 more or less is the de-facto standard for lat/long values these days, but that definitely needs to be specified. if you do have a gps, it very likely has some configuration screen where you can choose from a number of reference systems. this is important when you want to look up coordinates on a paper map: if the gps reference system and you map's coordinate system do not match, it is very hard to actually locate the coordinates on the map (the transformations can be fairly complex). as for elevation values, the reference system is much more important. devices can and do use different reference systems, or they may even use barometric elevation measurements (which tend to be more precise, depending on the number of satellite fixes), so for the elevation to make any sense, there definitely needs to be a reference system. and because it is entirely reasonable for a device to use gps values for lat/long and barometric values for the elevation, the reference system cannot be just one for the complete location, it must be specific for these values. and like i mentioned earlier, and somehow going in the same direction, i am very interested in the API supporting URI-based locations. in a way, this is just another "reference system", where instead of lat/long values, the location is defined by a URI scheme. like i said, i am not very happy with the current geo: scheme proposal (in particular the latest version of it, which switched to a tile-based scheme), but narrowing down location to lat/long only is a rather limited location concept. in particular, location URIs can provide a good solution for come of the privacy issues of the location API. URI-based location may use coordinate-based lat/long locations (such as proposed by the current geo: scheme draft), but they could also represent locations providing better privacy, such as city names, states, or entirely user specific locations, which still make sense in the context of interactions among closed user groups (e.g. on social networking sites), but have far fewer privacy implications than gps-precision coordinates. cheers, dret.
Received on Wednesday, 25 June 2008 17:01:24 UTC