Handle edge cases related to map updates whan altitude agl is slightly below zero (starting position).

Author: hmakelin

gisnav/data.py

@@ -579,6 +579,9 @@ def __post_init__(self):
 
         :raise: DataValueError if a valid FixedCamera could not be initialized
         """
+        if self.image_pair is None:
+            raise DataValueError('Please provide valid image pair.')
+
         img = self.image_pair.qry
         if self.snapshot.terrain_altitude.amsl is not None and self.snapshot.terrain_altitude.ellipsoid is None or \
             self.snapshot.terrain_altitude.amsl is not None and self.snapshot.terrain_altitude.ellipsoid is None:

gisnav/nodes/base_node.py

@@ -677,6 +677,9 @@ def _map_update_timer_callback(self) -> None:
         if map_update_altitude is None:
             self.get_logger().warn('Cannot determine altitude AGL, skipping map update.')
             return None
+        if map_update_altitude <= 0:
+            self.get_logger().warn(f'Map update altitude {map_update_altitude} should be > 0, skipping map update.')
+            return None
         map_radius = self._get_dynamic_map_radius(map_update_altitude)
         map_candidate = GeoSquare(projected_center if projected_center is not None else self._vehicle_position.xy,
                                   map_radius)
@@ -1124,6 +1127,9 @@ def _mock_map_data(self, origin: Position) -> Optional[MapData]:
         if altitude is None:
             self.get_logger().warn('Cannot determine altitude AGL, skipping mock map data.')
             return
+        if altitude < 0:
+            self.get_logger().warn(f'Altitude AGL {altitude} was negative, skipping mock map data.')
+            return
         radius = scaling * altitude
 
         assert_type(origin.xy, GeoPoint)