DataFlash: Update for AHRS NED changes

Report both origin and home NED altitudes to the log file

libraries/DataFlash/LogFile.cpp

@@ -1107,15 +1107,17 @@ void DataFlash_Class::Log_Write_POS(AP_AHRS &ahrs)
     if (!ahrs.get_position(loc)) {
         return;
     }
-    Vector3f pos;
-    ahrs.get_relative_position_NED(pos);
+    float home, origin;
+    ahrs.get_relative_position_D_home(home);
+    ahrs.get_relative_position_D_origin(origin);
     struct log_POS pkt = {
         LOG_PACKET_HEADER_INIT(LOG_POS_MSG),
-        time_us : AP_HAL::micros64(),
-        lat     : loc.lat,
-        lng     : loc.lng,
-        alt     : loc.alt*1.0e-2f,
-        rel_alt : -pos.z
+        time_us        : AP_HAL::micros64(),
+        lat            : loc.lat,
+        lng            : loc.lng,
+        alt            : loc.alt*1.0e-2f,
+        rel_home_alt   : -home,
+        rel_origin_alt : -origin
     };
     WriteBlock(&pkt, sizeof(pkt));
 }

libraries/DataFlash/LogStructure.h

@@ -210,7 +210,8 @@ struct PACKED log_POS {
     int32_t lat;
     int32_t lng;
     float alt;
-    float rel_alt;
+    float rel_home_alt;
+    float rel_origin_alt;
 };
 
 struct PACKED log_POWR {
@@ -835,7 +836,7 @@ Format characters in the format string for binary log messages
     { LOG_AHR2_MSG, sizeof(log_AHRS), \
       "AHR2","QccCfLL","TimeUS,Roll,Pitch,Yaw,Alt,Lat,Lng" }, \
     { LOG_POS_MSG, sizeof(log_POS), \
-      "POS","QLLff","TimeUS,Lat,Lng,Alt,RelAlt" }, \
+      "POS","QLLfff","TimeUS,Lat,Lng,Alt,RelHomeAlt,RelOriginAlt" }, \
     { LOG_SIMSTATE_MSG, sizeof(log_AHRS), \
       "SIM","QccCfLL","TimeUS,Roll,Pitch,Yaw,Alt,Lat,Lng" }, \
     { LOG_NKF1_MSG, sizeof(log_EKF1), \