Re: [OSM-talk] GPS Altitude vs Pressure Altitude article, Tool for measuring elevation above sea level
On 29.11.17 23:39, Martin Koppenhoefer wrote: sent from a phone On 28. Nov 2017, at 06:10, Oleksiy Muzalyev wrote: Besides the number of the satellites increased lately, and the quality of the GPS receivers is also improving. And everyone who has got a modern smartphone has got a GPS altimeter. Some smartphones and some consumer gps units also feature barometric altimeters. Our consumer GPS units, especially those in smartphones with their suboptimal antennas, are unsuitable for measuring elevation precisely, the accuracy in the z-direction, from what emerged from previous discussions about this, is about 10 times inferior with respect to x/y. cheers, Martin It seems the global sources of elevation are not precise either. For example, the OSM shows correctly that the elevation in this part of the New Orleans is below sea level: http://ausleuchtung.ch/elevation/?lat=30.017679032856247&lon=-90.19947052001955&zm=14&rd=2 However, the Google Map Elevation API shows 0 meters for the same area: http://www.enetplanet.com/ . It means the elevation data which was entered by the local mappers is more correct. And this is essential information for such flood risk zones. Certainly, one should calibrate an altimeter. For example, measuring the elevation at a location with the known elevation. I think it would be even better to have both the GPS and the barometric altimeter, and both calibrated on the day of actual measurements. Best regards, O. ___ talk mailing list talk@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk
[OSM-talk] Permanent IDs RFC (was part_of:wikidata)
Permanent IDs has been brought up several times, especially as part of the Wikidata ID discussion. I started a wiki page to outline the requirements and goals, but it might be incomplete, feel free to add / correct / comment. https://wiki.openstreetmap.org/wiki/Permanent_ID Once we reach the agreement on the goals, we can figure out the implementation strategy. On Tue, Nov 28, 2017 at 2:47 PM, Andy Mabbett wrote: > On 28 November 2017 at 16:40, Christoph Hormann wrote: > > > The problem is OSM is a map of the physical world, not a map of the > > world's databases. If Wikidata wants to create links between OSM and > > other databases that is great but so far i think no one has made a good > > case why this linking information should be stored in OSM rather than > > Wikidata. > > Then you are not paying attention. OSM IDs are volatile - far more > volatile than Wikipedia IDs, let alone Wikidata IDs. > > > Again my suggestion: Working on better ways to address features in OSM > > in a stable way from the outside would be much more productive > > Great! Let us know when you have a working solution, consensus to > implement it, and tools that work with it. > > -- > Andy Mabbett > @pigsonthewing > http://pigsonthewing.org.uk > > ___ > Tagging mailing list > tagg...@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > ___ talk mailing list talk@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] GPS Altitude vs Pressure Altitude article, Tool for measuring elevation above sea level
sent from a phone > On 28. Nov 2017, at 06:10, Oleksiy Muzalyev > wrote: > > Besides the number of the satellites increased lately, and the quality of the > GPS receivers is also improving. And everyone who has got a modern smartphone > has got a GPS altimeter. Some smartphones and some consumer gps units also feature barometric altimeters. Our consumer GPS units, especially those in smartphones with their suboptimal antennas, are unsuitable for measuring elevation precisely, the accuracy in the z-direction, from what emerged from previous discussions about this, is about 10 times inferior with respect to x/y. cheers, Martin ___ talk mailing list talk@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk
