Convert ADV velocity components from a xyz-based coordinate system to an enu-based coordinate system.
xyzToEnuAdv(x, declination = 0, cabled = FALSE, horizontalCase,
sensorOrientation, debug = getOption("oceDebug"))An adv object, i.e. one inheriting from adv-class.
magnetic declination to be added to the heading, to get ENU with N as "true" north.
boolean value indicating whether the sensor head is connected
to the pressure case with a cable. If cabled=FALSE, then
horizontalCase is ignored. See “Details”.
optional boolean value indicating whether the sensor
case is oriented horizontally. Ignored unless cabled is TRUE.
See “Details”.
optional string indicating the direction in which
the sensor points. The value, which must be "upward" or
"downward", over-rides the value of orientation,
in the metadata slot,
which will have been set by read.adv, provided that the
data file contained the full header. See “Details”.
a flag that, if non-zero, turns on debugging. Higher values yield more extensive debugging.
The coordinate transformation is done using the heading, pitch, and roll
information contained within x. The algorithm is similar to that
used for Teledyne/RDI ADCP units, taking into account the different
definitions of heading, pitch, and roll as they are defined for the
velocimeters.
Generally, the transformation must be done on a time-by-time basis, which is
a slow operation. However, this function checks whether the vectors for
heading, pitch and roll, are all of unit length, and in that case, the
calculation is altered, resulting in shorter execution times. Note that
the angles are held in (data$timeSlow, data$headingSlow, ...)
for Nortek instruments and (data$time, data$heading, ...) for
Sontek instruments.
Since the documentation provided by instrument manufacturers can be vague on
the coordinate transformations, the method used here had to be developed
indirectly. (This is in contrast to the RDI ADCP instruments, for which
there are clear instructions.) documents that manufacturers provide. If
results seem incorrect (e.g. if currents go east instead of west), users
should examine the code in detail for the case at hand. The first step is
to set debug to 1, so that the processing will print a trail of
processing steps. The next step should be to consult the table below, to
see if it matches the understanding (or empirical tests) of the user. It
should not be difficult to tailor the code, if needed.
The code handles every case individually, based on the table given below. The table comes from Clark Richards, a former PhD student at Dalhousie University [2], who developed it based on instrument documentation, discussion on user groups, and analysis of measurements acquired with Nortek and Sontek velocimeters in the SLEIWEX experiment.
The column labelled ``Cabled'' indicates whether the sensor and the pressure
case are connected with a flexible cable, and the column labelled ``H.case''
indicates whether the pressure case is oriented horizontally. These two
properties are not discoverable in the headers of the data files, and so
they must be supplied with the arguments cabled and
horizontalCase. The source code refers to the information in this
table by case numbers. (Cases 5 and 6 are not handled.) Angles are
abbreviated as follows:: heading ``H,'' pitch ``P,'' and roll ``R''.
Entries X, Y and Z refer to instrument coordinates of the same names.
Entries S, F and M refer to so-called ship coordinates starboard, forward,
and mast; it is these that are used together with a rotation matrix to get
velocity components in the east, north, and upward directions.
| Case | Mfr. | Instr. | Cabled | H. case | Orient. | H | P | R | S | F | M |
| 1 | Nortek | vector | no | - | up | H-90 | R | -P | X | -Y | -Z |
| 2 | Nortek | vector | no | - | down | H-90 | R | -P | X | Y | Z |
| 3 | Nortek | vector | yes | yes | up | H-90 | R | -P | X | Y | Z |
| 4 | Nortek | vector | yes | yes | down | H-90 | R | P | X | -Y | -Z |
| 5 | Nortek | vector | yes | no | up | - | - | - | - | - | - |
| 6 | Nortek | vector | yes | no | down | - | - | - | - | - | - |
| 7 | Sontek | adv | - | - | up | H-90 | R | -P | X | -Y | -Z |
| 8 | Sontek | adv | - | - | down | H-90 | R | -P | X | Y | Z |
1. https://www.nortekgroup.com/faq/how-is-a-coordinate-transformation-done
2. Clark Richards, 2012, PhD Dalhousie University Department of Oceanography.
See read.adv for notes on functions relating to
adv objects.
Other things related to adv data: [[,adv-method,
[[<-,adv-method, adv-class,
adv, beamName,
beamToXyz, enuToOtherAdv,
enuToOther, plot,adv-method,
read.adv.nortek,
read.adv.sontek.adr,
read.adv.sontek.serial,
read.adv.sontek.text,
read.adv, rotateAboutZ,
subset,adv-method,
summary,adv-method, toEnuAdv,
toEnu, velocityStatistics,
xyzToEnu