Hi, Interesting but I very much doubt they are not applying a geoid on top of the ellipsoid. If they can put maps of the earth on the device, they can put a geoid with a posting of 15´x15´!
I have been wondering about those barometric altimeters GPS for back packing. I have a none electronic altimeter with me normally but it only really good if you consider the temperature changes. Nicolas Cadieux https://gitlab.com/njacadieux > Le 20 avr. 2021 à 23:03, David Strip <[email protected]> a écrit : > > > In the course of trying to find what geoid model Garmin uses, I found this on > a Garmin support page: > . It is not uncommon for satellite heights to be off from map elevations by > +/- 400 ft. Use these values with caution when navigating. > Apparently some, but not all, models of the Garmin64 have a barometric > altimeter. Depending on your actual model, this may or may not apply. > > >> On 4/20/2021 8:23 PM, Nicolas Cadieux wrote: >> Hi, >> >> David gave you a very good answer. Your looking at a 11 meter difference. >> That is not much. The first thing would be to look at the gps measurement. >> (Any trees? Good satellite constellation? Any obstacles?). At best, your >> looking at a 6 to 10 meter error vertically. SRTMs are affected by trees. >> That would make the SRTM higher (not your case). Last thing to look at the >> the differences between the gps geiod model (a model of the average sea >> level). SRTM use EGM96. Your GPS probably uses something a bit more >> modern. You can easily get a 5 meter error between two Geiods. >
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