Thank you! In this article it is claimed that the barometric altimeters
are more accurate than GPS altimeters:
https://www.satmap.com/knowledge/Active_12/What_is_a_barometric_altimeter_.html
if re-calibrated periodically.
The barometric altimeters are available [1] , and they are not expensive.
However, a GPS altimeter also can be kind of calibrated by measuring an
elevation at a point with the known altitude right before starting to
perform the actual measurements. 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.
With this application if one clicks say at New Orleans, Louisiana, at
this point
http://ausleuchtung.ch/elevation/?lat=30.00890908440004&lon=-90.19363403320312&zm=14&rd=2
it is immediately clear that this area of the city is below sea level.
But this information is not visible clearly on the OSM map otherwise,
even one the Cycle layer.
[1]
https://www.amazon.com/Multifunction-Outdoor-Thermometer-Sport-YingYing/dp/B01KH4XK8W/ref=lp_219368011_1_11?s=sports-and-fitness&ie=UTF8&qid=1511844559&sr=1-11
Best regards,
Oleksiy
On 28.11.17 04:25, Jack Armstrong dan...@sprynet.com wrote:
Congratulations on your accomplishment.
Of course, elevation above sea level (MSL) for a fixed point on the ground does
not change no matter the pressure altitude (barometer setting). Pressure
altitude vs. using a QNH of 1013 for flight levels (high altitude), is
something mostly only pilots and air traffic controllers are concerned with and
have no bearing on ground mapping. The QNH or altimeter setting simply help the
pilot and/or controller better understand an aircraft's height above the ground.
But, I assume you understand this.
-chachafish
(38 years as an air traffic controller)
-----Original Message-----
From: Oleksiy Muzalyev <oleksiy.muzal...@bluewin.ch>
Sent: Nov 27, 2017 11:05 PM
To: Talk Openstreetmap <talk@openstreetmap.org>
Subject: [OSM-talk] GPS Altitude vs Pressure Altitude article, Tool for
measuring elevation above sea level
Hello everyone,
After reading a good article "GPS Altitude vs Pressure Altitude" [1] I
wrote a simple tool to calculate an elevation above the sea level at the
point of a click on the OSM map: http://ausleuchtung.ch/elevation/
More details are at the Diary entry:
https://www.openstreetmap.org/user/Alex-7/diary/42830
[1] http://www.borgeltinstruments.com/GPSvsPressurealtitude.pdf
Best regards,
Oleksiy
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