Survey of Vessels

Topics: Geodesy, Surveying, Global Positioning System Pages: 6 (882 words) Published: February 6, 2013
Survey of vessel reference systems, static and dynamic sensor calibration Seabed Mapping and Inspection Lokale kartdager 2008

Editor: Rolf Arne Ueland Speaker:Rolv Johannessen

October 6, 2008

• • • • • • From Blom to Parker Survey of vessel reference systems Use of close range photogrammetry GPS based static calibration of Sensors GPS based dynamic calibration of sensors Experience


From Blom to Parker
• Blom ASA demerged into mapping and offshore technology divisions, June 2007 • Blom Maritime was renamed Scan Maritime and joined Scan Rope in Scan Subsea ASA • Scan Subsea ASA was acquired by Parker Hannifin 16th of November 2007 • Parker Maritime (new name from Febr. 2008) will continue to supply our services to existing and new clients 3

Experience from survey of vessel sensors
• During 2007 we performed more than 60 Gyro & DGPS calibrations • We surveyed 17 Multibeam echo sounder and sensor installations • Similar work was also performed on Shuttle Tankers and subsea structures • Our clients are Survey vessels, Seismic vessels, Offshore construction vessels and equipment manufacturers 4

Vessel reference systems
• Purpose
• To establish a precise vessel bound coordinate system to position and align all survey sensor

• Requirements
• Better sensors and positioning increase demand for precision in the vessel reference system

• Methods
• Free station survey with total station • Close range photogrammetry for flatness and alignment 5

Survey of vessel sensors - Method
• Total station (TDM5005)
• Combination of teodolite and Electronic Distance Meter

• Close Range Photogrammetry


Principles of free point survey – Vessel


Principles of free point survey – Cont • Define points to be surveyed

Deck-points, Helideck, VRS, GPS antennas, Echo sounder, HPR (e.g. HiPap), Artemis, FanBeam (distance meter), Other reference points, Establish reference points and lines for e.g. calibration of ROV gyro. In dock: Draft marks, keel, rudderstock (Aft Perpendicular) and all sensor underside hull


Principles of free point survey – Cont • Establish station 1


Principles of free point survey – Cont
• Add Station 2 and observe common fix points


Principles of free point survey – Cont
• Add Station 3


Principles of free point survey – Cont
• Add Station 4


Principles of free point survey – Cont
• Add Station 5……

Continues with stations onboard (and in) the vessel

Principles of free point survey – Cont
• From each station:
• Measure sensors, permanent fix points and vessel axis alignment points • Direct sights to point • Distance measured to reflective stickers, magnetic targets or prism targets. 14

Reference systems – Calculations
• We calculate all observations into a common 3D coordinate system • Stations are tied together by transformation through common points • We perform an on site data inspection and quality control • Final transformation to a defined vessel axis system and reference plane • Results reported as coordinates and sketches 15

Use of close range Photogrammetry
• Close Range Photogrammetry
• Marking with coded targets and scale bars • Image acquisition, Image analysis • Object reconstruction

• Accuracy factors


Use of close range Photogrammetry - cont


Close Range Photogrammetry
• So far performed on • HU Sverdrup, Viktor Hensen, Acergy Viking and Acergy Petrel • Conclusion • Good for flatness control during installation of EM 710 • Good redundancy and documentation of accuracy • Must be tied to the vessel system by the total station measured points • Accuracy and time to perform similar to total station 18

GPS based static calibration of Sensors
• Method
• Based on calculating baseline heading between two GPS antennas

• Equipment and tools
• We use Javad HD2 GPS (plus GLONAS) heading sensor and AttCon software.

• Gyro, DGPS, RGPS other
• Challenges can...
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