Convert ADP velocity components from a beam-based coordinate system to a
xyz-based coordinate system. The action depends on the type of object.
Objects creating by reading RDI Teledyne, Sontek, and some Nortek
instruments are handled directly. However, Nortek
data stored in in the AD2CP format are handled by the specialized
function beamToXyzAdpAD2CP(), the documentation for which
should be consulted, rather than the material given blow.
beamToXyzAdp(x, debug = getOption("oceDebug"))an integer specifying whether debugging information is
to be printed during the processing. This is a general parameter that
is used by many oce functions. Generally, setting debug=0
turns off the printing, while higher values suggest that more information
be printed. If one function calls another, it usually reduces the value of
debug first, so that a user can often obtain deeper debugging
by specifying higher debug values.
An object with the first 3 velocity indices having been altered to
represent velocity components in xyz (or instrument) coordinates. (For
rdi data, the values at the 4th velocity index are changed to
represent the "error" velocity.)
To indicate the change, the value of x[["oceCoordinate"]] is
changed from beam to xyz.
For a 3-beam Nortek aquadopp object, the beams are transformed into
velocities using the matrix stored in the header.
For 4-beam objects (and for the slanted 4 beams of 5-beam
objects), the along-beam velocity components \(B_1\)
\(B_2\), \(B_3\), and \(B_4\)
are converted to Cartesian velocity components \(u\)
\(v\) and \(w\)
using formulae from section 5.5 of RD Instruments (1998), viz. the
along-beam velocity components \(B_1\), \(B_2\), \(B_3\),
and \(B_4\) are used to calculate velocity components in a cartesian
system referenced to the instrument using the following formulae:
\(u=ca(B_1-B_2)\), \(v=ca(B_4-B_3)\),
\(w=-b(B_1+B_2+B_3+B_4)\). In addition to these,
an estimate of the
error in velocity is computed as
\(e=d(B_1+B_2-B_3-B_4)\).
The geometrical factors in these formulae are:
c is +1 for convex beam geometry or -1 for concave beam geometry,
\(a=1/(2\sin\theta)\)
where \(\theta\) is the angle the beams make to the axial direction
(which is available as x[["beamAngle"]]),
\(b=1/(4\cos\theta)\), and
\(d=a/\sqrt{2}\).
Teledyne RD Instruments. “ADCP Coordinate Transformation: Formulas and Calculations,” January 2010. P/N 951-6079-00.
WHOI/USGS-provided Matlab code for beam-enu transformation http://woodshole.er.usgs.gov/pubs/of2005-1429/MFILES/AQDPTOOLS/beam2enu.m
See read.adp() for other functions that relate to
objects of class "adp".
Other things related to adp data:
[[,adp-method,
[[<-,adp-method,
ad2cpHeaderValue(),
adp-class,
adpEnsembleAverage(),
adp_rdi.000,
adp,
as.adp(),
beamName(),
beamToXyzAdpAD2CP(),
beamToXyzAdv(),
beamToXyz(),
beamUnspreadAdp(),
binmapAdp(),
enuToOtherAdp(),
enuToOther(),
handleFlags,adp-method,
is.ad2cp(),
plot,adp-method,
read.adp.ad2cp(),
read.adp.nortek(),
read.adp.rdi(),
read.adp.sontek.serial(),
read.adp.sontek(),
read.adp(),
read.aquadoppHR(),
read.aquadoppProfiler(),
read.aquadopp(),
rotateAboutZ(),
setFlags,adp-method,
subset,adp-method,
subtractBottomVelocity(),
summary,adp-method,
toEnuAdp(),
toEnu(),
velocityStatistics(),
xyzToEnuAdpAD2CP(),
xyzToEnuAdp(),
xyzToEnu()