Fix ProjectedSonarImage comments about frame

acoustic_msgs/README.md

@@ -45,13 +45,13 @@ adheres to these guidelines:
       of the standard message, following the Image/CameraInfo pattern.
   - In order to support generality for a wide range of sensors, there will be some
     fields that are not applicable to some sensors.
-    (e.g. per-beam elevation angles; per-beam beamwidth)
-    * If not supported at all, leave that array empty
-    * If value is constant across the data frame, array should be length 1
+    * If not supported at all, the array may be left empty.
+    * If value is constant across the data frame, array may be length 1.
     * Otherwise, the length of each array should match the length of the data.
-* Underwater acoustic messages should include the speed of sound
+* "raw/temporal" Underwater acoustic messages should include the speed of sound
   (field will be called sound_speed) that was used by the sensor, as well as any
   information required to raytrace the data with a new sound velocity profile.
+* "processed/spatial" acoustic messages will have the ray-tracing already performed.
 * The beam geometry is specified as a per-beam vector relative to the frame in
   the header. This is an alternative to other approaches that have been used, including:
   * additional TF frames for individual beams, which will quickly become unwieldy

acoustic_msgs/msg/Dvl.msg

@@ -4,8 +4,6 @@
 # repository, which was released under a BSD license.
 # Modifications were made by UW-APL.
 
-# TODO: check style concistency with sonar messages for
-
 # ENUM: Velocity mode
 uint8 DVL_MODE_BOTTOM=1
 uint8 DVL_MODE_WATER=2
@@ -25,6 +23,9 @@ uint8 DVL_TYPE_PHASED_ARRAY=1
 # The standard ROS header.
 # Timestamp is neither transmit nor receive time -- it is the time that
 # the velocity should be considered valid at.
+# Frame convention:
+# * z-axis in direction DVL is pointing
+# * x-axis aligned with vehicle forward
 std_msgs/Header header
 
 # Velocity mode (see above)

acoustic_msgs/msg/ProjectedSonarImage.msg

@@ -1,18 +1,18 @@
 # Single scan from an imaging sonar
 #
-# The X-axis is centered in the plane of the fan ("forward"), with Z down,
-# in order to be consistent with the NED convention.
+# The Z-axis is centered in the plane of the fan ("forward"), with X up,
+# in order to be consistent with the NED for traditional multibeam profilers.
 #
-# For sonars with a 1D array, the beams lie on the X-Y plane, and
-# and each beam has an azimuth (rotation about Z) value.  Zero azimuth
-# is in the direction of the X-axis, typically "straight out" from the sonar.
+# For sonars with a 1D array, the beams lie on the Y-Z plane, and
+# and each beam has an azimuth (rotation about X) value.  Zero azimuth
+# is in the direction of the Z-axis, typically "straight out" from the sonar.
 # Elevation is the orthogonal direction (rotation about Y),
 # often termed the "vertical aperture"
 
-# The meaning of the header timestamp relative to the sonar's data
-# acquisition cycle is defined by the sonar driver. It is taken to be
-# a best estimate of the time when the sonar data is valid, which will
-# the timing information available from the sonar hardware.
+# The header time should be the time the ping was transmitted, not
+# the time the message was received.
+# Note that these two could potentially be several seconds apart,
+# especially in deep water.
 std_msgs/Header header
 
 PingInfo ping_info