In my experience of walking with various GPSes and smart phones over the last 14 years the altitude derived by the satellites won't be good, no where near as good as the 3 to 5 meters or so of the horizontal accuracy you can normally rely on. read this https://wiki.openstreetmap.org/wiki/Altitude
If the altitude is derived from the barometer which some gpses have ( my experience is of Garmins) and some smart watches have it can be very accurate for a short time but it will drift as the weather changes. Set it to the known height or pressure and walk up or down a slope and it will display the mapped heights very closely, don't forget you are probably reading it above waist height so allow for that, this reading will give you a location on a good contoured map of your point on the trail up or down the slope but if you then camped for the night air pressure will have changed and so your altitude reading will be incorrect and require resetting, which you can do with that map if you can pinpoint yourself on a contour line. Incidentally the pressure change could help you predict the weather. You've seen the films " The glass is falling fast Captain a storms a coming!". pressure was read by height of mercury in the glass tube. Most OSM based maps that have contour use SRMT as far as i know See https://wiki.openstreetmap.org/wiki/SRTM
Happy mapping
answered
26 May, 13:01
andy mackey
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What application are you using?
Altitude from consumer grade GPS devices is usually useless.
"useless" is a misleading generalisation - as with anything, "useful" depends on what you're trying to use to for. Barometric altitude has been available in consumer devices for many years and if calibrated regularly will answer the "how far up the hill am I" question just fine.
I presume they talk about OSMand where you can download additional contour lines to overlay the map. But I haven't used the app in months, cannot tell what kind of altitude information it can display.
@alan_gr: I use OsmAnd+, paid version for Android 9. But meanwhile I have to partially retract, or reformulate my question. With GPS and mobile data, the altitude IS shown. The problem happens when no direct GPS signal is present, mainly indoors. My impression, that it may persist also outdoors (balcony, garden), as long as the WiFi signal is present and dominant. I was confused, because the location is always shown correctly, even indoors, and I thought that the altitude is recalculated from the location anyway.
So, my question can be updated as follows. Can the altitude data be displayed correctly indoors?
Another thing is that the “altitude” can be activated only via “Configure Map”, but not in the “Show”, or “Details”, or other menus. In general, I find OSM menus over-complicated to the degree that they become counter-intuitive and confusing.
While I'm not familiar enough with OsmAnd to describe what it actually does, what I'd expect an app to show is the altitude that the device is reporting. If you're using a phone without a barimetric altimeter then it'll only be able to give you the GPS altitude which will be (a) only accurate to within 10s or 100s of meters (this is what H_mlet was alluding to above I think) and (b) not available when you have no GPS signal.
What device are you actually using?
I don't know enough about the OsmAnd app to answer. Maybe you can find something at the specific website for that app, https://osmand.net/help-online.
I think by "OSM menus" you mean OsmAnd in particular. OsmAnd is just one of many apps that use data from OSM (OpenStreetMap). It also uses other data - e.g. if it shows contour lines they are not coming from OpenStreetMap data. This help site is for openstreetmap.org and for OpenStreetMap in general - e.g. questions about how to map something. It is not generally the best place for questions or observations about specific apps, although you might be lucky if a user of the app happens to be active here.
@SomeoneElse: Thanks, the Phone is Huawei P Smart Z. It does not have a barimetric altimeter. It should recalculate from the GPS location data. Meanwhile, I am just surprised that it does not do it indoors, although the correct location is still shown there. @alan_gr: Thanks, you are right, I should look at the OsmAnd+ help.