<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Hi, </div><div><br></div>Thanks for the precision. So they are basically prone to the same problem (which is reassuring). My guess is that the true befits is that they add a compass with the barometer so you can take a heading reading when not moving... I guess that is worth 100 bucks! <div><br></div><div>Guess we’re moving away for the topic here... shitty ADHD! :)<br><br><div dir="ltr">Nicolas Cadieux<div><a href="https://gitlab.com/njacadieux">https://gitlab.com/njacadieux</a></div></div><div dir="ltr"><br><blockquote type="cite">Le 21 avr. 2021 à 08:26, kirk <kirk@nortekresources.com> a écrit :<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><div dir="auto">Hi Nicolas.</div><div dir="auto"><br></div><div dir="auto">You can set the barometer my using a known point and elevation or by setting the current atmospheric pressure. As with an anologue altimeter, your readings will change throughout the day as the pressure changes. This is less of a problem if you are out on a sunny day with a high pressure cell with a small pressure gradient. but becomes bit more problematic if a low pressure system is moving in.</div><div dir="auto"><br></div><div dir="auto"><br></div><div id="composer_signature" dir="auto"><div style="font-size:85%;color:#575757" dir="auto">Sent from my Galaxy</div></div><div dir="auto"><br></div><div><br></div><div align="left" dir="auto" style="font-size:100%;color:#000000"><div>-------- Original message --------</div><div>From: Nicolas Cadieux <njacadieux.gitlab@gmail.com> </div><div>Date: 2021-04-21 9:14 a.m. (GMT-04:00) </div><div>To: David Strip <qgis-user@stripfamily.net> </div><div>Cc: Qgis Users List <qgis-user@lists.osgeo.org> </div><div>Subject: Re: [Qgis-user] (no subject) (elevation question) </div><div><br></div></div>Hi,<div><br><div>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´! </div><div><br></div><div> 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. </div><div><br><div dir="ltr">Nicolas Cadieux<div><a href="https://gitlab.com/njacadieux">https://gitlab.com/njacadieux</a></div></div><div dir="ltr"><br><blockquote type="cite">Le 20 avr. 2021 à 23:03, David Strip <qgis-user@stripfamily.net> a écrit :<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
<div class="moz-cite-prefix">In the course of trying to find what
geoid model Garmin uses, I found this on a<a href="https://support.garmin.com/en-US/?faq=QPc5x3ZFUv1QyoxITW2vZ6">
Garmin support page</a>:<br>
<blockquote>. It is not uncommon for satellite heights to be off
from map elevations by +/- 400 ft. Use these values with caution
when navigating.<br>
</blockquote>
Apparently some, but not all, models of the Garmin64 have a
barometric altimeter. Depending on your actual model, this may or
may not apply.<br>
<br>
<br>
On 4/20/2021 8:23 PM, Nicolas Cadieux wrote:<br>
</div>
<blockquote type="cite">
<div>Hi,</div>
<div><br>
</div>
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.</blockquote>
<br>
</div></blockquote></div></div></div></blockquote></div></body></html>