The method I use for calibrating the barrometric altitude functionality in my biking app is to use the gps to get a location I then use Googles Elervation API <https://developers.google.com/maps/documentation/elevation/> to get an altitude for this location and adjust my reference pressure to get the barometric based altitude to match. Haveing done this the relative altitude reading during a bike ride tend to be good but if the weather is changing a lot you can easaly be +-50m by the end of of a few hours riding. Aviation services should have the reference pressure for vaious airfields airfields avalable. I would investigate the various weather service api to see what is avalable but I think your going to strugle with what you are trying to achieve the weather is just too big a variable over significant time periods. Ifor
On Monday, 31 December 2012 07:26:44 UTC, sebouh00 wrote: > Sorry, but you're just repeating what Mark said. It's not helpful. > > I am not looking for a solution with GPS. My research shows GPS is bad at > altitude calculations. And I'm sure it uses more power to get an altitude > because it requires time and outdoors to get a lock, but I have no tests to > show that. > > I asked where I can get real-time sea-level pressure data. I didn't get an > answer. > > > On Monday, December 31, 2012 1:45:46 AM UTC+3, Lew wrote: >> >> sebouh00 wrote: >> >>> Wouldn't I need a lock on the GPS location in order to get the altitude? >>> I would assume that would take more time, hence more power then just using >>> the barometer. >> >> >> Less power + wrong answer/no answer = ? >> >> What about the altitude apps. How do they usually determine the >>> approximate altitude. Do they suffer from +/- 500 meter inaccuracy? >>> >> >> My brief Google search indicates GPS. I think not. >> >> What does your online search tell you? >> >> Mark Murphy (a Commons Guy) wrote: >>> >>> sebouh00 wrote: >>> > I would like to save the altitude in my app and use it to check if the >>> > device is at the same altitude in the future. Using GPS will not be >>> > applicable because of minimal power usage restrictions in my app. >>> >>> What tests have you run to determine that the barometer is >>> sufficiently lower power than the GPS radio? I suspect it is, but I >>> have never tried testing the scenario. >>> >>> > Would it be possible to do such a thing? >>> >>> IMHO, not reliably. If you are trying to get altitude accuracy +/- 500 >>> meters or so, perhaps. >>> >>> http://en.wikipedia.org/wiki/Atmospheric_pressure >>> http://en.wikipedia.org/wiki/Altimeter >>> >>> Moreover, none of this has anything to do with Android, and it smacks >>> of premature optimization, unless you have already implemented the >>> GPS-based solution and proven that the power consumption is over your >>> budget. >>> >> >> Here Mark sends you to basic information about what you're trying to do. >> Your next >> response repeats the plaint that you don't know what you're doing. This >> despite your >> having just received relevant information. I suggest that you digest the >> information and >> utility of advice already offered. >> >> In case you missed it: >> - Barometric pressure will not do what you're asking /per se/. >> - You have not provided evidence that the GPS power requirements are >> egregious. >> - You have not commented on whether comparison with a topographic map >> plus >> recalibration, as suggested, will solve your problem. I'm guessing you >> haven't even >> tried it. >> >> -- >> Lew >> >> -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
