Historic Gasholder 3D Documentation

Historic Gasholder 3D Documentation featured

3D Laser Scanning and Architectural Documentation of D15 Gasholder in Technopolis City of Athens, Greece


The complete architectural 3D documentation of the historic D15 Gasholder, located in Technopolis City of Athens, was an essential prerequisite for its maintenance and restoration works. The project was assigned to Astrolabe Engineering in 2014 by Technopolis City of Athens SA, and led to the monument’s current status, finalized in 2016.

Technopolis City of Athens, one of the most renowned cultural hubs in the city nowadays, is house in the historic Gasworks Plant of Athens, which was established in 1857. It is considered to be the most recognizable and important monument of the industrial heritage in Athens. The unique industrial monument has now transformed into the most vibrant cultural multispace in the heart of the city, open and accessible to all, with more than one million visitors per year. Concerts, exhibitions, performances, screenings, educational programs and actions of the Industrial Gas Museum, seminars and workshops dedicated to new technologies, initiatives for the development of entrepreneurship and innovation and events of social nature are only some of the 900 events that take place every year in Technopolis.

The D15 Gasholder was the largest of the four gasholders of the historic plant, with a capacity of 15.000 cubic meters. It is also the largest gasholder ever constructed and operated in Greece. The metallic structure was built in 1909 in a telescopic form with an open spaceframe by the French company Bonnet Spazin & Co.

Project tasks

  • 3D laser scanning using a Faro Focus3D scanner:
    • 60 scans
    • 5mm resolution
    • intensity and RGB color
    • +/-2mm accuracy
  • Georeferencing in HGRS’87 (EGSA’87) coordinated system
  • Data processing for the final poincloud generation
  • 3D architectural documentation and preparation of deliverables

Conclusions – Results

A complete set of digital documentation products was generated, which was used as background information for subsequent design and construction works:

  • 3D RGB georeferenced pointcloud
  • 360 panoramic images interactive dataset
  • Orthoimages (elevations, unfolded elevations, layouts, sections, details)
  • Architectural vector drawings
  • Architectural documentation report

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Industrial Scan2BIM project in progress

3D scanning NOVAL Scan2BIM FARO Focus

NOVAL PROPERTY assigned ASTROLABE the as-built 3D documentation of the former VIOHALCO factory


NOVAL PROPERTY is one of the dominant Real Estate Investment Companies in Greece. Its portfolio of assets consists of office buildings, shopping centres, hotels and former industrial buildings of a total built-up area of about 430,000 sq.m. The total portfolio’s estimated value is about 300 million euros.

One of its latest development projects is the urban regeneration of the former Viohalco industrial asset (currently HALCOR sales department) at 252 Pireos str. in Athens. This is an investment of 120 million euros for the creation of the first supra-local pole of tourism and culture in the center of Athens (city resort). The plan features two hotels, a park of more than 30,000 sq.m., playgrounds, a museum, a technology research and development center, catering and leisure facilities, sports facilities and a rehabilitation center. The uses of culture will cover more than 30% of the built-up areas, while the tourist infrastructure will cover 45%. The investment has already received the green light from the inter-ministerial committee on strategic investments. It will provide for the creation of 800 new jobs.

The industrial Scan2BIM project

The industrial building complex resides on a land parcel of 72569 sq.m. and consists of 26 buildings with a total built-up area of 43868 sq.m. The purpose of this industrial Scan2BIM survey, being executed by ASTROLABE is the complete documentation of the as-built status of the buildings. An accurate and up-to-date BIM model, as well as detailed architectural and structural 2D drawings will be generated . For the field data collection, we have engaged two 3D laser scanning crews. They are both equipped with FARO Focus scanners, capturing pointcloud data and high resolution panoramic images. As a result, we expect to conclude the survey, consisting of more than 1,000 scans, in 10-15 days. Our Scan2BIM team has already started to process the first 3D data coming from the field.

Stay tuned for an upcoming case study!

Update: July 2020

Field data capture has been concluded on schedule. 3D poincloud processing is almost completed for the whole complex. For better project development, three partial deliveries have been arranged (building groups A, B and C). Enjoy a 3-minute “sneak preview” video of our ongoing Scan2BIM processing:

3D4Delphi Research Project launched!

Modeling archaeological uncertainty by combining modern 3D surveying methods for scientific documentation and promotion of cultural heritage – Application in the archaeological site of Delphi

EPAnEK logo

We are excited to announce that, after a long anticipated approval decision, our 3D4Delphi Research Project is finally starting! You are invited to check what it is about. More information to be published as the Project progresses.

The partners

Ministry of Culture logo
Hellenic Mediterranean University logo
Technical University of Crete logo
Astrolabe Engineering logo
CreThiDev logo
JGC logo

The 3D4Delphi concept

The objective of the 3D4Delphi project is the development of new innovative methods of documentation, analysis and promotion of cultural heritage monuments combining modern techniques of 3D surveying and mathematical modeling of archaeological uncertainty, with its integration in the three-dimensional reconstruction of archaeological monuments itself.

In archaeological representation, it is common to create diverse scenarios of the original state of a monument and to revise such plans based on more recent information.

In the area of Delphi, there are important monuments which inherently communicate elements of uncertainty regarding the reconstruction of their past form. For these monuments, diverse non-invasive 3D data capture techniques will be applied, through terrestrial and aerial (via drone or UAV) imagery, laser scanners or optical scanners of varied principles of operation, ranges and accuracies, the results of which will be integrated,  in order to be optimally used for the scientific documentation of cultural heritage.

Then, based upon the 3D captured data, the development of mathematical models of archaeological uncertainty will be conducted in relation to the potential form of an archeological structure in the past. This will provide multiple variants of three-dimensional reconstructions based on historical data and excavation findings, which will offer a whole new set of uses for archaeological 3D models that will broaden the horizons of archaeological research, such as investigating archaeological hypotheses, comparing uncertainties between different models, and identifying areas where further archaeological research may be required. 

The results and the three-dimensional documentation and reconstruction methods that will emerge from this project will be presented in a pilot interactive demonstration setup, that will be designed and installed at the Museum of Delphi. Furthermore, the 3D documentation methods will provide the basis for the development of Augmented Reality (AR) applications, implemented with modern software development tools.

Visitors will have the opportunity to browse the archaeological site while receiving, on a mobile phone or on a specialized AR display, 3D information in relation to the archaeological monuments as they may have existed in the past, including elements of archaeological uncertainty, combined with real-world exhibits, so that they can acquire the sense of “cultural experience” and broaden their knowledge.

Firefighting Training Center Scan2BIM project completed

Astrolabe Engineering recently completed an important Scan2BIM project for the Firefighting Training Center building complex, located in Nea Makri, Attica, Greece. A former USA military base, the Nea Makri building complex has been since the 1990s under the authority of the Greek Fire Service (FS).

In the summer of 2018, in the aftermath of the devastating fires that hit Greece and cost the lives of more than a hundred of citizens, the Stavros Niarchos Foundation (SNF) had announced a donation of € 25,000,000 to support the FS. The construction of a fully specialized and equipped training center for the training of FS employees was set as a priority, the creation of which had been a confirmed and ongoing need since the establishment of the Service (1930). With the donation of the SFN, the fulfillment of this need will become a reality at the facilities of the former USA base in Nea Makri.

A team of experts from the architectural firm Betaplan SA determined the scope and cost of construction work at the training center based on the technical specifications drafted by the FS. Additional technical specifications for the use and operation of the center have also been defined. The total cost for the creation of the training center is estimated to reach € 15,300,000.

The FS and Betaplan SA on January 2020 signed a contract for the elaboration of the “Complete Design and Supervision of the Fire Service Training Center in Nea Makri”. As part of this main contract, Betaplan SA hired Astrolabe Engineering as a sub-contractor for the Survey of the as-built condition of the buildings.

Astrolabe Engineering performed a detailed 3D laser scanning survey of 21 existing building in total, which, in combination with additional detailed measurements, enabled the generation of 3D Building Information Models (BIM), detail drawings and inspection maps of the structural metallic frames per building. These deliverables are already being used as a background for all subsequent design (architectural, structural, etc) and construction activities under the main contract.

A detailed case study will be availabe on our website’s related section soon. Check out some sample images!

Visit our booth at BUILD-EXPO 2019!

We are pleased to announce the participation of ASTROLABE ENGINEERING at BUILD-EXPO GREECE 2019 which will take place at the Metropolitan Expo in Athens from October 18th to 20th.

You are invited to visit our booth (27A at Hall 1, Coriddor A) to learn more about the capabilities, methods and products related to our 3D laser scanning – Scan to CAD and Scan to BIM services.

Join the ECOMED webinar!

Learn about the ECOMED Project and join the network!

Click here to download the ECOMED Webinar Invitation



Dates (alternatively): Wednesday, Nov 29, 2017 OR Thursday, Nov 30, 2017

Time: 11:00am to 12:00pm

Duration: 1 hour

Presenter: Michael Xinogalos, Surveying Eng. NTUA

Register now!

About the ECOMED project

The aim of this project is to generate a sector-specific theoretical and practical syllabus essential for the specialization process of the Mediterranean Ecoengineering sector.

Also, to jointly develop a long-term interaction scheme among the stakeholders of the ecoengineering sector and to deliver a training courses programme technology enhanced in “Soil and Fluvial ecoengineering, Hazard Assessment and Techniques Selection in Mediterranean Environment”.

This new syllabus will be generated during the implementation of the long-term strategy of the proposal “Specialisation process for the ecoengineering sector in the Mediterranean environment (ECOMED)”.

Highway as-built 3D Mapping

As-built 3D mapping and modeling of Highways in Greece: Korinthos – Tripoli highway (static TLS), Elefsina – Korinthos highway (mobile TLS)


Concession Self Financing Projects have been, during the last decade, a common practice for the construction of road transport networks. The basic concept is that a large private J/V undertakes the construction of a new highway section and in the same time takes the responsibility for the maintenance (and improvement) of an existing highway section, from which it collects the toll fees, in order to finance the whole project. After completing the project, the J/V has its full exploitation for a certain number of years, according to the concession contract.

An obvious need for detail surveys of the existing highway sections arises from the whole process. These surveys usually require:

  • Detail “as-built” survey of all highway features (pavement, structures, slopes, signage, poles, etc).
  • Efficient archiving of “as-built” situation for future reference.
  • Positional accuracy: 2-3 cm.
  • Elevation accuracy: 1-2 cm.
  • 3D model (TIN) for highway reconstruction design.
  • Background survey maps (scale 1:500).
  • No significant traffic closure or delay.
  • Efficient safety plan.
  • Permits from local traffic authorities.

Applying TLS methodology

Terrestrial Laser Scanning techniques have been applied in two cases of existing highways (dual carriageway, 2-3 lanes & shoulder), using two different approaches:

Korinthos – Tripoli highway (length 80 km, J/V MOREAS) was surveyed in 2006-2007 using a static (scan & go) approach with an Optech ILRIS 36D Laser Scanner.
Elefsina – Korinthos highway (length 60 km, J/V APION KLEOS) was surveyed in 2008 using a mobile approach with the newest Optech LYNX Mobile Mapper.

Project Tasks

a. Korinthos – Tripoli: Field work tasks and parameters

  • Establishment of geodetic infrastructure networks (triangulation, leveling, polygonometry), also necessary for construction.
  • Static (stop & scan) laser scanning with Optech ILRIS36D.
  • Scanner carried by a vehicle moving or standing always on the shoulder lane, protected by a traffic regulation trailing vehicle.
  • Scanning from both sides of the highway, distance between scanning positions 50-80m.
    1100 total scanning stations, 120 working days for 80 km of highway.
  • Critical issue for horizontal objects: lifting the scanner (better scanning angle, improved object visibility, lower scanning resolution and / or fewer scanning positions required).
  • Lifting device used: Genie Super Hoist (5.6m, 113 kg capacity, CO2).
  • Custom modifications: Trailer integration, 5/8 bolt, longer ethernet and power cables, stabilizers, fuel generator & UPS, etc.
  • Scanning resolution: 55mm @ 25m horizontal / 20mm @ 25m vertical.
  • Pan-tilt base overlap set to maximum (20% overlap, 15 frames/3600).
  • Primary georeferencing: with conic targets (standard traffic cones: easy to install, measure and model), 1 cone (anchor point) per scan position required for sequential georeferencing.

b. Elefsina – Korinthos: Field work tasks and parameters

  • Establishment of geodetic infrastructure networks (triangulation, leveling, polygonometry), also necessary for construction.
  • Mobile laser scanning with Optech LYNX Mobile Mapper (collaboration with SINECO).
    Sensors – GPS/IMU carried by a vehicle moving at 50 km/h on the shoulder and left lane, protected by traffic regulation vehicles.
  • 2 passes for each carriageway (shoulder lane – left lane) for better data quality.
    240 km total scanning distance, 1 working day for 60 km of highway.
  • Base GPS station support (6 base stations on known points).
  • Measurement of positional Ground Control Points (natural targets identifiable on pointcloud).
  • Basic data processing / alignment and delivery of georeferenced pointclouds in 500 m segments for each carriageway.
  • Conversions between global (WGS84/UTM/zone 34) and local (CGRS87) geodetic reference systems.
  • Positional GCP alignment for groups of 3-5 segments of 500 m (typical target registration accuracy < 3cm).

c. Common post-processing tasks

  • Georeferencing refinement for elevations: using additional points measured on both edges of each carriageway every 50-80m (typical elevation alignment accuracy < 1 cm).
  • Feature collection from pointclouds.
  • 3D Modeling (TIN) from features and Survey Maps (scale 1:500) generation.
  • Archiving for future reference: Pointclouds segmented per km.

Results – Conclusions

While the newest mobile TLS approach using the LYNX Mobile Mapper is obviously the method of choice, the static approach with the ILRIS still has some advantages and can be applied at least for smaller road sections, taking into account also the cost of the two systems. The comparison conclusions between the two methods, in terms of data quality, accuracy and productivity are presented below:

Data Quality


  • Uniform resolution homogeneous pointclouds.
  • No unnecessary overlaps.
  • Less noise from passing traffic.
  • Better object coverage with 2 sensors.


  • Better detail for close objects.
  • Better viewing angle when lifted.
  • Produces organized pointclouds (with normal vectors).



  • No errors from overlapping frame ICP alignment.
  • No errors from sequential scan positions ICP alignment.
  • Good relative accuracy for segments of 500 m.


  • No errors from GPS outage or poor satellite conditions.
  • No errors from attitude compensation.
  • Excellent relative accuracy for each frame.
  • Lifting device can lower accuracy with bad weather conditions.



  • Field works: Dramatically faster (1 day vs months) and safer.
  • Faster alignment and georeferencing of datasets.
  • Significantly faster and easier noise cleaning.
  • Automated feature extraction tools work better with uniform density homogeneous pointclouds.


  • Easier manual feature collection with shaded organized pointclouds.
  • Advanced filtering techniques work only with organized pointclouds.
  • Better level of detail for close objects (resolution – viewing angle).

Related Videos

Tanks 3D Inspection

Tanks 3D inspection and deformation analysis at HELPE SA Aspropyrgos refinery / Aspropyrgos, Athens – Greece


During a refinery’s operation, it is a common maintenance task to periodically check tanks and other equipment for deformations, in comparison to their theoretical geometry. Significant deformations are a sign of tank wall weakening and pose a risk of critical damage, thus repairing measures have to be consider.

Project tasks

A cylindrical and a spherical tank at HELPE SA Aspropyrgos refinery were checked for deformations using 3D laser scanning methodology. The cylindrical tank was empty and was scanned internally from a single position, while the spherical one was operational and was scanned externally from 3 positions. After basic processing and alignment of scans, the final pointclouds were used for tank wall inspection. In particular, a cylinder and a sphere where best fitted to the respective pointclouds and deviations from those ideal primitive geometries where calculated. Results were presented in 3D, as well as in 2D sections properly spaced, in order to facilitate locating and quantifying the deformations.

Results – Conclusions

3D laser scanning is an ideal methodology for this kind of maintenance inspections of industrial facilities’ equipment due to fast data capture, non-contact measurement, high accuracy and, most important, complete 3D coverage of the scanned objects. Thus, the whole object is efficiently being checked, while specialized software makes inspection tasks quite easy to perform and their results comprehensively presentable.

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Plant 3D survey & PDMS Modeling

Plant Survey and Intelligent 3D Modeling of HELPE SA Aspropyrgos refinery – Vacuum Gas Oil Storage Area / Aspropyrgos, Athens – Greece


Hellenic Petroleum SA holds a leading position in the Greek energy sector, as well as in the greater area of Southeast Europe. In Greece, the Group owns and operates three refineries, in Aspropyrgos, Elefsina and Thessaloniki. The three refineries, combined, cover 76% of the country’s total refining capacity.

As in many refineries and other industrial facilities all over the world, the as-built status of existing equipment and components of the Aspropyrgos refinery is poorly documented. Documentation consists mainly of 2D drawings which are geometrically inaccurate, incomplete and eventually obsolete. Furthermore, for many years, all designed expansions, repairs and maintenance works have been based on those existing drawings, resulting in on-site undocumented interventions, making the situation worse.

Everyday maintenance and management tasks represent a significant part of the refinery’s operation cost. To reduce these costs, HELPE SA investigated methodologies to create a reliable as-built registry of its existing equipment, which, through industry standard solutions will incorporate the results in everyday operation of the facility.

Thus, a pilot plant survey and intelligent 3D modeling project was awarded for the Vacuum Gas Oil Storage Area (of medium difficulty), in order to demonstrate the efficiency of the proposed methodology under real conditions, to reveal possible problems, to clarify the owner’s requirements regarding the contents and level of detail of the intelligent 3D model and attached information, to define the format of deliverables (3D model and digital drawings’ specifications) and finally to ensure the smooth incorporation of the results to the operational procedures of the refinery.

Project tasks

The pilot project’s area is approximately 27,400 sq.m. large and includes, among other equipment, 4 storage tanks, about 300 pipes and a rather complicated pump station with 19 pumps. The project’s tasks were elaborated in two phases:

Phase A consisted of the 3D laser scanning survey works, including:

  • TLS survey using an Optech ILRIS3D laser scanner:
    • 35 total scanning positions
    • 10 days of scanning
    • About 300 millions of points collected
    • Average resolution: 1-2 cm
    • Accuracy < 1cm
    • Georeferencing by assigning coordinates (based on the refinery’s geodetic network) to most scanning positions and additional control points
    • Assigning RGB color to points from internal or external camera photos
  • Basic processing of TLS data and other measurements.
  • Alignment of adjacent pointclouds and georeferencing using control coordinates.
  • Segmentation and preparation of pointclouds for easier management by the 3D modeling software.

Phase B consisted of the intelligent 3D modeling process, using industry standard plant 3D modeling software, including:

  • Transfer of the georeferenced pointclouds to the 3D modeling software.
  • Taking digital photos of the area to be modeled.
  • Collection from the owner of:
    • All available drawings (Plot Plans, General Arrangements, P&IDs, Isometrics, Piping Layouts, etc).
    • All available specifications (for piping, instrumentation, materials, insulation, structures, etc).
    • Drawing and document naming and abbreviations procedures
  • Software Database Creation regarding:
    • Equipment
    • Materials
    • Piping classification
    • Column and Beam Specification
  • Creation of intelligent 3D model, based on the assets of the created database, on pointcloud geometry and on the information provided by the owner.

The above 3D model was made easily available to the owner in 3D PDF format, together with its attached component database tree structure. Furthermore, the final intelligent 3D model was used to automatically extract updated sample digital drawings for the surveyed pilot area.

Results – Conclusions

Intelligent 3D Models of plant establishments have proven to be an essential tool for plant management, maintenance and design. In addition to the geometric accuracy that a simple 3D CAD model can provide, an intelligent 3D model associates every object with a library of components and their full specifications, thus reflecting the true as-built geometrical and – most important – functional state of the plant at the time of the site survey.

Using appropriate reverse engineering software tools, an intelligent 3D model can be used to automatically generate any kind of drawing (PlotPlans, General Arrangement, Isometrics, P&IDs, EFDs), to design expansion components, to perform collision checking, to extract material lists, to schedule maintenance tasks, to perform stress analysis and other calculations and even to totally monitor, control and manage a plant environment.

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Training and on-project support for SAUDI UNICOM on mobile surveying workflows using the Optech Lynx Mobile Mapping System


SAUDI UNICOM Group, with its headquarters located in Riyadh, Saudi Arabia, is a major player in the Arabic, as well as in the global market, in many sectors (trade, industrial, telecommunications, software, media, etc). Its Geoinformation subdivision, U-MAPS, made in 2011 a strategically significant investment by purchasing a high-end mobile mapping system from OPTECH, the LYNX M1. The system was delivered by OPTECH together with the standard company’s high quality on-site setup, calibration and training services.

UNICOM, having undertaken a quite large mobile mapping project, the survey of major corridors for the “Jeddah Storm Water Drainage Program”, realized the urgent need for extended on project training and support, in order to:

  • Incorporate as fast as possible the mobile surveying technology in their standard mapping workflows.
  • Choose the most appropriate from both the technical and financial point of view post-processing software solutions and practices.
  • Create an efficient and productive field and office team, able to elaborate the undertaken project within a strict and pressing time schedule.
  • Understand all the aspects and best practices of mobile surveying projects (mission planning, accuracy, resolution, reference GNSS stations, control points, local datum conversions, pointcloud matching and georeferencing, feature extraction, modeling, etc).
  • Ensure the quality of deliverables and their compliance to specifications.

Project tasks

For this purpose, UNICOM engaged Astrolabe Engineering, investing in its extensive experience in “start to finish” mobile surveying workflows using the OPTECH LYNX Mobile Mapper. Astrolabe responded swiftly by providing training and support during field data collection in Jeddah, KSA, training UNICOM’s personnel in Riyadh, KSA and Cairo, Egypt and also undertaking some urgent post-processing tasks to assist in on-time delivery of the first project sections. On-line remote extended support was also made available according to UNICOM’s needs.

Results – Conclusions

As a result, UNICOM / U-MAPS successfully and timely completed all undertaken tasks for the project, having gained the trust of a major client in the area. Furthermore, UNICOM possesses now a fully trained, productive and efficient field and office team for mobile surveying services, having elevated mobile surveying using the OPTECH LYNX Mobile Mapper to the company’s major mapping activity.