laser scanning

a report by

S t e v e n E B r own

Director, Plant Segment, Cyra Technologies, Inc.

I n t r o d u c t i o n

Modifying an existing offshore platform (or anyfacility for that matter) can be a daunting task. Any engineering company, owner operator orconstruction contractor who has tackled an offshoreretrofit is well aware of this challenge. Tight spaces,densely packed equipment and a difficult operatingenvironment combined with a tight timeframe forfield construction creates engineering challenges thatoften carry a high penalty when errors occur. Anderrors do occur! Most platform owners, engineeringfirms, equipment vendors and constructioncompanies have experienced significant difficultieswith retrofit projects at one time or another. Theresults are major cost overruns and/or scheduledelays as well as ‘field compromises’ required to getthe platform back online as quickly as possible.

These construction issues and delays can frequentlybe traced back to either inaccurate or missing as-builtinformation used as critical input to the design andconstruction/demolition planning of the retrofit.The root causes of the poor quality as-builtinformation lie, in turn, in the traditional methodsfor gathering as-built information: engineers extract‘as-built’ information from original design/construction drawings and supplement thisinformation by taking additional as-builtmeasurements manually. Both these techniques areprone to error. Existing drawings are rarely, if ever,accurate, and good manual measurements areextremely difficult to obtain. In addition, even whenaccurate manual measurements can be taken, manycritical measurements may be missed due to oversightor later changes in design/scope. The result is fieldconstruction interferences, fit-up problems and costlyon-site changes.

Today, these problems (and costs) can be avoidedwith the use of Cyrax Laser Scanning technology.

Wha t i s C y r a x L a s e r S c a n n i n g ?

Cyra Technologies, a San Ramon, California-basedcompany and subsidiary of Leica Geosystems AG,introduced Cyrax® laser scanning in 1998 and is the

largest supplier in the laser scanning industry with over300 systems shipped through December 2002. Thetripod-mounted Cyrax laser scanner sweeps a pulsinglaser over the facility, collecting up to 1,000 individualsurface geometry measurements per second. Bymeasuring precisely the time of flight for the laserpulse (distance) and two angles (horizontal and verticalrotating mirrors), a rich, dense ‘three-dimensional (3-D) point cloud’ of facility geometry is created. Eachindividual point measurement is accurate within +/-6mm up to a range of 50 metres. By averagingthousands of points on surfaces, a few millimetresprecision can typically be achieved when point cloudsare processed into as-built models and drawings.

To capture full 3-D geometry of the area(s) ofinterest, the laser scanner is moved around theplatform or facility as needed. Once multiple scans ofa facility (offshore or onshore) are collected, they are‘registered’ together and typically tied to a local co-ordinate system using several known surveypoints. The registration process can utilise bothknown common points (target registration) as well asmatching of common surfaces within the pointclouds (cloud-to-cloud registration). Even largestructures such as offshore platforms can be scannedeasily and the scan data tied together accurately, asshown in Figure 1. This project consisted of 43 scans(roughly 43 million measurements) capturing theareas of critical interest for the retrofit. The scanswere collected in less than two days.

Since the laser scanner literally ‘blankets’ the scene,designers can easily identify all objects (valves,flanges, strainers, structural elements) they areworking with (see Figure 2). The point clouds can beused within Cyra’s Cyclone™ software for rapidcreation of accurate, complete as-built models, or,with Cyra’s CloudWorx software, the points can beused directly within the AutoCAD or Microstationdesign environment to extract measurements orcreate as-built drawings. This allows designers tomodel existing piping, structures and equipmenteasily using familiar design tools while referencingthe point cloud as an accurate ‘3-D road-map’.Through CloudWorx, plant design software such asPDS, AutoPLANT, CADWorx and Plant4D can all

3-D Laser Scann ing for Smoother Of f shore Ret ro f i t s

B U S I N E S S B R I E F I N G : E X P L O R A T I O N & P R O D U C T I O N 2 0 0 3

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Technology & Services

take advantage of rich point clouds for creation ofaccurate as-builts for interference-free design.

T h e B e n e f i t s o f C y r a x L a s e r S c a n n i n g a n d Mod e l l i n g

Rapid, accurate, complete measurements combinedwith the easy-to-use Cyclone and CloudWorxsoftware allow the designer to create truly accurateas-builts quickly and easily and/or create new designsthat are interference-free. The result is reduced cycletime, reduced engineering effort, lower project costand on-time construction completion.

The areas that laser scanning has impacted over thepast number of years are many.

E l i m i n a t i o n o f R e w o r k

This is an obvious and well-documented benefit.Through the increased accuracy achieved by laserscanning, construction contractors are finding thatpiping spools and prefabricated structural elements fitright the first time. Reports of ‘zero rework’ arecommon. This, in turn, means no downtime whiletrying to make corrections, no expensive standbytime for lifting equipment and no delays in plantstart-up due to ‘field adjustments’. Interferences havebeen eliminated in advance.

L o w e r C o s t D e s i g n

When laser scanning is used during the design phase,fewer field trips are required in order to obtaingeometric data. In essence, the point cloud databrings the ‘3-D field reality’ right to the designer’sdesktop. Rather than relying on surveyor notes anda few point measurements, the designer can now

‘virtually’ navigate through the facility, view,measure and design based on complete data. Directmeasurements from the point clouds can be takenquickly and utilised for the design. This not onlyreduces costly and time-consuming field trips tocollect missing information, but also increases theconfidence in the design, thus allowing for fewerfield welds. In one small project alone, over 40 fieldwelds were eliminated after laser scanning data wasincorporated into the design process.

Another major saving in the design phase is theability of multiple disciplines to share the same 3-D point cloud information. Rather than eachgroup (electrical, piping, structural, etc.) collectingand using their own field data, a single set of pointcloud data can be utilised. This not only savesmoney (and time) in the data collection phase, butensures consistency of the information being usedfor the design. Since everyone can view the samedata, numerous potential conflicts can be avoidedin advance.

R e d u c e d C y c l e T i m e

Due to the rapid collection of field data andminimal ‘post processing’, a reduction in projectdesign cycle time can be achieved. Since each laserpoint is already a 3-D measurement, the raw pointclouds can be used directly for design once they areregistered and tied to the appropriate co-ordinatesystem. No interpretation or translation of fieldnotes is required and there is no need to process2-D drawings into 3-D.

I m p r o v e d S a f e t y

Rather than climb ladders and piping or deal withlifting devices and safety harnesses, a Cyrax laserscanner allows the data to be collected remotelyfrom a distance of up to 50 metres. This also enablesthe field crew to obtain accurate measurementssafely and quickly even in inaccessible or otherwisehazardous locations.

F l e x i b l e W o r k F l o w

A full suite of software products allows the user toselect the work flow that is appropriate for theproject. If a basic geometry model is required for usewithin computer-aided design (CAD), the Cyclonesoftware can be used to create and export therequired model quickly. In addition, if desired,object intelligence can be added through the use of a‘Piping Mode’, which incorporates Alias SKEYsterminology. Once the piping is created with theSKEYs, it can be output into the Alias pcf format andthen translated into AutoPLANT, PDS and PDMSformats using Alias products.


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Technology & Services

Figure 1: Offshore Platform Scan

3-D Laser Scann ing for Smoother Of f shore Ret ro f i t s

An accurate, intelligent as-built can also be createddirectly by combining a 3-D design system such asAutoPLANT with CloudWorx for AutoCADapplication. CloudWorx 2.0 Pro automatically fitspoint clouds to pipe centrelines directly in the CADenvironment, thus enabling the designer to modelexisting piping elements quickly and accurately usingfamiliar tools.

If the objective is simply a new, interference-freedesign, CloudWorx can be used within the CADenvironment to view the raw points and create thenew design around them.

Since the plant modelling tools are typically familiarto the designer, and the learning curve forCloudWorx is minimal, high-level production canbe achieved quickly. In addition, very little‘organisational resistance’ is typically encounteredsince no-one is being asked to make a major changein work practices and deliverables. Now, instead ofreviewing surveyor notes, they simply pull the pointdata directly into their CAD station.

Whe r e / H ow C y r a x L a s e r S c a n n i n g i sB e i n g U s e d

Service providers who own laser scanners andsoftware are often contracted to provide sets ofregistered point clouds or as-built drawings andmodels. Laser scanners and software can also bepurchased or rented and some owner/operators havegone this route as well. Today, the technology isavailable worldwide. Typical costs for services arecomparable to costs of as-builts done manually(sometimes less), but the results are far more accurateand complete and the deliverables are availablesooner. Cyrax laser scanning and software are beingused in the offshore and onshore petrochemicalindustries and manufacturing facilities of many types.Initially considered a tool for only large-scaleprojects, it has evolved rapidly to prove cost-effectivefor small-scale modifications to major revamps.Projects ranging from several hundred million dollarsto a few hundred thousand dollars have all been ableto reap the benefits of 3-D laser scanning technology.

3-D laser scanning technology was originally focusedon the design phase, but it has also proven beneficialduring the construction phase. Plants underconstruction have been scanned (and sometimesmodelled) for use in developing crane placements

and 3-D rigging plans. Construction verification anddeviation analysis (quality control) are additionalareas that have benefited from this technology. Insome cases, contractors have been able to resolvedifficult field issues more quickly by having the 3-Dpoint cloud data available to them.

As this tool becomes more familiar to designcompanies, construction companies and owneroperators, the number and variety of uses seem to belimited only by the human imagination. ■


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Figure 2: Point Cloud Shrinkwrap

Figure 3: CloudWorx with AutoPLANT

laser scanning

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