From 0a6bf66088e0255768383bb56aacaf20f9c90b08 Mon Sep 17 00:00:00 2001
From: tsteven4 <13596209+tsteven4@users.noreply.github.com>
Date: Tue, 23 Jul 2024 14:57:25 -0600
Subject: [PATCH] correct garmin real time altitude, add geoid height. (#1303)

---
 garmin.cc | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/garmin.cc b/garmin.cc
index ca642c3e7..d676e33df 100644
--- a/garmin.cc
+++ b/garmin.cc
@@ -579,7 +579,13 @@ GarminFormat::route_read()
 void
 GarminFormat::pvt2wpt(GPS_PPvt_Data pvt, Waypoint* wpt)
 {
-  wpt->altitude = pvt->alt;
+  // pvt->alt is height (in meters) above the WGS84 elipsoid.
+  // pvt->msl_hght is height (in meters) of WGS84 elipsoid above MSL.
+  // wpt->altitude is height (in meters) above geoid (mean sea level).
+  // wpt->geoidheight is "Height (in meters) of geoid (mean sea level) above WGS84 earth ellipsoid."
+  wpt->set_geoidheight(-pvt->msl_hght);
+  wpt->altitude = pvt->alt + pvt->msl_hght;
+
   wpt->latitude = pvt->lat;
   wpt->longitude = pvt->lon;
 
-- 
2.30.2