Add Altitude.msg

sensor_msgs/CMakeLists.txt

@@ -18,6 +18,7 @@ find_package(rosidl_default_generators REQUIRED)
 find_package(std_msgs REQUIRED)
 
 set(msg_files
+  "msg/Altitude.msg"
   "msg/BatteryState.msg"
   "msg/CameraInfo.msg"
   "msg/ChannelFloat32.msg"

sensor_msgs/README.md

@@ -16,6 +16,7 @@ This package provides some common C++ functionality relating to manipulating a c
 * [point_field_conversion.hpp](include/sensor_msgs/point_field_conversion.hpp): A type to enum mapping for the different PointField types, and methods to read and write in a PointCloud2 buffer for the different PointField types.
 
 ## Messages (.msg)
+* [Altitude](msg/Altitude.msg): Single vertical position (altitude/depth) measurement.
 * [BatteryState](msg/BatteryState.msg): Describes the power state of the battery.
 * [CameraInfo](msg/CameraInfo.msg): Meta information for a camera.
 * [ChannelFloat32](msg/ChannelFloat32.msg): Holds optional data associated with each point in a PointCloud message.

sensor_msgs/msg/Altitude.msg

@@ -0,0 +1,41 @@
+# Single vertical position (altitude/depth) measurement.
+#
+# Units & sign (REP-103): meters, +Z up. Negative altitude indicates depth
+# below the chosen reference.
+#
+# Semantics (REP-105):
+# - 'altitude' is the vertical position along the +Z axis of header.frame_id.
+# - header.frame_id is the frame in which the measurement is expressed
+#   (e.g., base_link, imu_link, map, earth).
+#
+# Reference:
+# The 'reference' field indicates what this measurement is relative to:
+#   REFERENCE_UNKNOWN (0): unspecified or mixed semantics.
+#   REFERENCE_DATUM   (1): relative to a vertical datum / ellipsoid / geoid.
+#                         When used, 'datum' should name the model, e.g.
+#                         "WGS84", "EGM96", "MSL", or a local datum identifier.
+#   REFERENCE_SURFACE (2): relative to a local physical surface (ground, seabed,
+#                         water surface). Typical for AGL/height-above-surface sensors.
+#
+# Uncertainty:
+# - 'variance' is the measurement variance in m^2; 0.0 indicates unknown.
+
+# Reference enumeration
+uint8 REFERENCE_UNKNOWN=0
+uint8 REFERENCE_DATUM=1
+uint8 REFERENCE_SURFACE=2
+
+# Timestamp and frame of the measurement
+std_msgs/Header header        # timestamp is when the altitude was measured;
+                              # frame_id is the frame whose +Z defines "up"
+
+# Scalar vertical position
+float64 altitude              # Vertical position in meters (+Z up); negative for depth
+
+# Measurement uncertainty
+float64 variance              # 0 is interpreted as variance unknown
+
+# Optional name of the datum/surface
+string datum                  # Name of vertical datum or surface if applicable
+                              # (e.g., "WGS84", "EGM96", "MSL", "GROUND", "SEA_SURFACE");
+                              # empty if unknown or not applicable