Re: altitude measurement

hello martin.

Thomson, Martin wrote:
> If the specification gets into the topic of resolving differences from multiple sources of data, then it will never be finished.  The answer depends on circumstance to a large extent.  Better to leave that up to those who need to resolve these problems: the people who do the measuring.  Better that than lump web developers with the mess.

again, i do see the point of complexity being risky. but calling 
additional information "the mess" is not really what i am looking for, 
and the mess will not just disappear because you would prefer not to see 
it. if you expect API implementors to deal with the mess, shouldn't you 
have an idea of how they should do it? i am really looking for an answer 
to that, rather than just saying "wouldn't it be great if there was just 
a single set of values that would work for everybody".

> The problem with additional information is that you then need further information to help people make use of the mess.  At a minimum you need to provide information on how to interpret each so that those who are only interested in the answer can make use of it.

sure, each set of values would come with whatever labels we come up 
with, such as "GPS EGM96 altitude" and "barometric altitude". i am not 
advocating to leave things unspecified.

> Your hiking example is a good example of a person having to compensate for a shortcoming in technology - the GPS gives you altitude relative to the ellipsoid, not "sea level"; the barometric altimeter is affected by weather.  You compensate for each in your own fashion, and multiple sources are used for redundancy - to compensate for any potential errors.  In doing so you apply a fair amount of additional knowledge.

exactly. and i am happy that i can do this, because i do get the 
different measurements from my device. others might prefer to just see 
one simple value which is the "best effort" provided by the device. that 
diversity of approaches is only possible if you expose all information.

> I'm willing to bet that web developers aren't interested in managing all that complexity for what could be a single scalar.

maybe, maybe not. this depends very much on the scenario you are looking 
at. are we just trying to feed google maps, or are we also looking at 
more sophisticated ways to build applications based on geoposition data?

cheers,

dret.

Received on Monday, 5 January 2009 03:57:35 UTC