add logging for gpos terrain alt

src/modules/sdlog2/sdlog2.c

@@ -1432,6 +1432,11 @@ int sdlog2_thread_main(int argc, char *argv[])
 			log_msg.body.log_GPOS.vel_d = buf.global_pos.vel_d;
 			log_msg.body.log_GPOS.eph = buf.global_pos.eph;
 			log_msg.body.log_GPOS.epv = buf.global_pos.epv;
+			if (buf.global_pos.terrain_alt_valid) {
+				log_msg.body.log_GPOS.terrain_alt = buf.global_pos.terrain_alt;
+			} else {
+				log_msg.body.log_GPOS.terrain_alt = -1.0f;
+			}
 			LOGBUFFER_WRITE_AND_COUNT(GPOS);
 		}
 
@@ -1464,7 +1469,7 @@ int sdlog2_thread_main(int argc, char *argv[])
 			log_msg.body.log_VICN.yaw = buf.vicon_pos.yaw;
 			LOGBUFFER_WRITE_AND_COUNT(VICN);
 		}
-		
+
 		/* --- VISION POSITION --- */
 		if (copy_if_updated(ORB_ID(vision_position_estimate), subs.vision_pos_sub, &buf.vision_pos)) {
 			log_msg.msg_type = LOG_VISN_MSG;

src/modules/sdlog2/sdlog2_messages.h

@@ -220,6 +220,7 @@ struct log_GPOS_s {
 	float vel_d;
 	float eph;
 	float epv;
+	float terrain_alt;
 };
 
 /* --- GPSP - GLOBAL POSITION SETPOINT --- */
@@ -449,7 +450,7 @@ static const struct log_format_s log_formats[] = {
 	LOG_FORMAT(AIRS, "fff",			"IndSpeed,TrueSpeed,AirTemp"),
 	LOG_FORMAT(ARSP, "fff",			"RollRateSP,PitchRateSP,YawRateSP"),
 	LOG_FORMAT(FLOW, "hhfffBB",		"RawX,RawY,CompX,CompY,Dist,Q,SensID"),
-	LOG_FORMAT(GPOS, "LLffffff",		"Lat,Lon,Alt,VelN,VelE,VelD,EPH,EPV"),
+	LOG_FORMAT(GPOS, "LLfffffff",		"Lat,Lon,Alt,VelN,VelE,VelD,EPH,EPV,TALT"),
 	LOG_FORMAT(GPSP, "BLLffBfbf",		"NavState,Lat,Lon,Alt,Yaw,Type,LoitR,LoitDir,PitMin"),
 	LOG_FORMAT(ESC, "HBBBHHHHHHfH",		"count,nESC,Conn,N,Ver,Adr,Volt,Amp,RPM,Temp,SetP,SetPRAW"),
 	LOG_FORMAT(GVSP, "fff",			"VX,VY,VZ"),