GCS CYSCAN - Defining Reflector Positions

47CyScan Positioning System • Installation and Maintenance Guide r1.1
GC S
GC S
Defining Reflector Positions
To achieve the most accurate results, please follow the suggestions given below when
defining the coordinates of installed reflectors.
• Target positions are measured using two perpendicular axes, A and B. The Origin
of the two axes can be any fixed point on the Mooring Point/Vessel, with all
measurements along both axes being taken from that point.
If the reflectors are mounted along the side of the Mooring Point/Vessel, then the
logical arrangement (and the most straightforward for measuring reflector posi-
tions) is to make the A and B axes match those of the vessel (as shown below).
This would involve the B axis passing across the vessel (starboard to port, or vice
versa), while the A axis would run parallel to the side of the vessel (stern to bow,
or vice versa).
B
3
B_supply vessel
B
A
A
3
A
2
B
2
R
3
R
2
R
1
A_supply vessel
MOORING POINT/VESSEL
SUPPLY
VESSEL
(ORIGIN)
θ_supply vessel
Defining Reflector Positions
The Origin can be any fixed point on the vessel,
however, in most cases it will be defined as the
first reflector R
1
. The remaining reflectors are
defined relative to the origin using the
perpendicular axes A and B running through it.
• If the Mooring Point/Vessel has no particular fixed reference point, then it is
recommended that the first reflector, R1 is designated as the Origin.
• The reflectors should be numbered starting from the one on the far right (as
viewed from the expected working area) and continuing anticlockwise through the
other reflectors.
• The direction in which each reflector faces must be declared to the CyScan Con-
sole. All measurements are made using the direction of the reflector face relative
to the direction of the A axis. Using a centreline running through the reflector,
perpendicular to the reflector face, the angle between this line and the A axis is
measured and declared to the system.
Using the above diagram as an example, the perpendicular centrelines of all the
reflectors are parallel to the B axis, but pointing in the opposite direction (i.e. they
are facing the sea) – therefore they all have a rotation (or Orientation) of 270
degrees.
• The reflector definitions must be entered in the order R1, R2, R3, etc.
• When using auto-survey the first reflection detected in each rev will be used as the
datum or primary target defining the origin of the A/B coordinate frame.
Please refer to the following three pages for examples of typical reflector layouts.