Inspection – High Speed High Intensity Photogrammetry

Data for Out of Straightness Fugro Survey Limited Aberdeen

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Fugro

SeaStriper

Fugro Survey

Limited

Aberdeen

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Specifications for OOS surveys are constantly

increasingly comprehensive and onerous on the

survey contractor to collate and present high quality

and high quantity data.

In response to the ever increasing demands on the

survey teams to comply with these specifications

Fugro have developed a suite of hardware and

software tools to enable this to occur efficiently.

OSS Surveys

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Currently OOS Data is collected from dual head Multi-

Beam Echo Sounder data and high accuracy

positioning sensors or odo wheels in contact with the

pipeline. This requires very highly skilled ROV pilots.

Current OOS data deliverables are of the top of pipe

from generally manually picked from the data set. The

positions and depth provided is raw and non-tidally

corrected.

The interval of the top of pipe reporting is ever

decreasing.

There have been many advancements in Multi-Beam

Echo Sounder technology determining the top of pipe

can still be a very onerous task and open to

interpretation.

ROV MBES trenched pipeline profile data

ROV MBES trenched pipeline data

Current data collection

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The SeaStriper system is a Fugro proprietry high

resolution optical survey solution.

SeaStriper collects an accurate 3D point cloud of

complex subsea infrastructure using non-contact,

vision and laser technologies.

SeaStriper is a precise, robust and adaptable subsea

survey system designed especially for subsea pipeline

inspection.

SeaStriper data

MBES Data

Fugro SeaStriper

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SeaStriper has the following components:

Two pairs of calibrated machine vision cameras

Two green laser stripers (150 mW Class IIIb)

Camera control unit (CCU)

Interconnecting cables (CCU to ROV)

Starfix.NG SeaStriper Solution

ROV Requirements

• INS Positioning Solution

• Gigabit Ethernet & Trigger Line

• 12-30v DC Power

Skid Mounted

Bar Mounted

SeaStriper Components

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ROV Multi-beam Echo Sounder Calibrations require

approximately 4 hours to acquire and process to allow

for operations to commence.

Seastriper takes approximately 10 minutes of

observations by the cameras on a target table at

varying altitudes and headings followed by 10 minutes

of computer number crunching. After this the system

is ready to undertake OOS survey operations.

Calibration

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As seen in the data examples the density of raw data

allows for clearer identification of the pipe line and the

top of pipe compared to Multi-Beam Echo Sounder

data.

Data examples

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Combined Data Set

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The SeaStriper data is handled as a pseudo MBE

device.

Once all the data is present in the database the Top of

Pipe (TOP) is automatically picked from the

SeaStriper data in the Starfix Suite using Fine Pick,

little manual work is required on this due to the highly

dense and precise data.

If the SeaStriper is imaging the seabed adjacent to the

pipeline then the Seabed Adjacent Level (ADJ)

markers are also assigned using the previously

defined TOP as reference.

If only the pipeline is being imaged by the SeaStriper

then no seabed markers can be assigned to this data.

The TOP is injected into the Reson MBES data and

the Natural Seabed Level (SBL) assigned using the

Reson MBES data.

Automated

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Accuracy

FSLTD used a section of data to model in Leica Cyclone. This was acquired using FCV3087 with

SeaStriper running at 8Hz.

Distance between ‘stripes’ along pipeline: 20 – 40 mm

Distance between data points on each stripe: 2 – 4 mm.

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The SeaStriper data was also modelled by best fitting

a cylinder to the point cloud at regular intervals along

the data set.

This allowed FSLTD to compare SeaStriper measured

OD against client supplied, as well as pipe position

and depth.

Client Supplied OD: 0.363m

SeaStriper measured OD: 0.359m (Min: 0.354, Max: 0.363)

Accuracy

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Project Trial – OOS

There are two bottle-necks in the current processing workflow when working with MBES data alone;

cleaning the data and assigning the pipeline marker. These two processes require time-consuming

manual intervention to complete, to varying degrees, depending on the quality of the acquired data.

The SeaStriper does not use acoustic data therefore the amount of noise present in the data is minimal

and generally does not require manual cleaning.

The automatic pipeline picking routine in Sfx.Edit requires a substantial amount of data points on the

pipeline in order for the algorithm to successfully place the pipeline marker, Seastriper enables this.

When this is not successful, the alternative is to manually assigning the marker for each cross profile

which is a time-consuming process.

The increased precision and density of the SeaStriper data (over MBES) results in the pipeline being

successfully automatically picked and therefore little manual work is required.

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Top of Pipe from MBES

Top of Pipe from SeaStriper

Project Trial – OOS

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Differences between MBES, ODO and SeaStriper

Project Trial – OOS

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Differences between MBES, ODO and Seastriper

Project Trial – OOS

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Time Saving

The below statistics are calculated for one hour of data surveying at 600 m/hr and processing MBES at

1m intervals.

In summary, utilising SeaStriper on a 28 days ‘standard’ project with three processors on the vessel

results in 9.3 man days of time saved, this is due to the increased density and precision of the data, over

MBES, which allows more automated post processing routines to be utilised.

This frees the senior processor to fully manage the reporting rather than being the pipe expert. The data

is also available to the client sooner.

Processing Navigation

[Mins]

Sfx.Proc

Cleaning Data [mins]

Sfx.SwathEdit

Assigning markers [mins]

Sfx.Edit

Total time

[mins] Speed Gain

Option 1

2x MBES 10 5 45 60

1.5 Option 2

2x MBES & 2x Seastriper 21 5 15 41

3 processors 36.0 Man hours per day

28 day project

(70% acquisition time) 19.6 Acquisition days

Option 1 705.6 Project man days

Option 2 482.2 Project man days

223.4 Man hours saved

9.3 Man days saved

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• With the requirement for high specification OOS

surveys new tool need have been developed to

achieve the requirement.

• Increase in speed and accuracy allowing for

additional time savings.

• Additional information can be provided and

increased statically analysis

• Future development to the system is only

restricted to what we can ‘see’

Conclusion

Fugro Survey Limited

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information required to design,

construct and maintain your

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