Astrolabe Engineering
innovation for efficiency
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)
Purpose
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
LYNX:
- Uniform resolution homogeneous pointclouds.
- No unnecessary overlaps.
- Less noise from passing traffic.
- Better object coverage with 2 sensors.
ILRIS:
- Better detail for close objects.
- Better viewing angle when lifted.
- Produces organized pointclouds (with normal vectors).
Accuracy
LYNX:
- No errors from overlapping frame ICP alignment.
- No errors from sequential scan positions ICP alignment.
- Good relative accuracy for segments of 500 m.
ILRIS:
- 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.
Productivity
LYNX:
- 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.
ILRIS:
- 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
Work With Us
Planning an as-built survey of a road or highway corridor? We would be glad to discuss the right approach — static or mobile laser scanning — for your project. Contact us or explore our services.
Tanks 3D Inspection
Tanks 3D inspection and deformation analysis at HELPE SA Aspropyrgos refinery / Aspropyrgos, Athens – Greece
Purpose
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.
Related Videos
Work With Us
Need to inspect tanks or industrial equipment for deformation? We would be glad to discuss how 3D laser scanning can support your maintenance program. Contact us or explore our services.
Plant 3D Scan-to-PDMS Modeling
Plant Survey and Intelligent 3D Modeling of HELPE SA Aspropyrgos refinery – Vacuum Gas Oil Storage Area / Aspropyrgos, Athens – Greece
Purpose
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.
Related Videos
Work With Us
Looking to create an accurate as-built record of your plant or industrial facility? We would be glad to discuss how Scan-to-PDMS modeling can work for your site. Contact us or explore our services.
Training SAUDI UNICOM
Training and on-project support for SAUDI UNICOM on mobile surveying workflows using the Optech Lynx Mobile Mapping System
Purpose
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.
Work With Us
Thinking about mobile mapping training or on-project support for your team? We would be glad to discuss what we can offer. Contact us or explore our services.
Airport Tarmac Inspection
Tarmac 3D modeling and deformation analysis of airplane roundabout loops / Athens International Airport “El. Venizelos” – Greece
Purpose
The airplane traffic at the Athens International Airport towards its 2 air-corridors (eastern and western) is regulated through 4 roundabout loops, 2 for each corridor. Due to the traffic load, the fact that the heavy aircrafts often have to stop at the loops and the type of the pavement, the tarmac at those 4 areas has developed noticeable deformations. So, the technical department of the A.I.A., in order to define the extent of the damage and decide what kind of corrective actions should be taken (from simple tarmac repairs to full pavement reconstruction), requested a detailed 3D modeling of the tarmac surface, followed by a complete deformation analysis. The methodology should combine a high level of detail (measurement every 2-3 cm), speed (each loop could remain closed only for a few hours) and accuracy (<1cm for elevations).
Project tasks
- A 3D laser scanning survey, using the Optech ILRIS 36D Laser Scanner, was performed (6 to 9 scan positions per area, scanner on top of a car, tripod mounted, 20% pan-tilt base overlap, distance between scans <50m).
- Georeference was obtained using conic and circular targets, measured from the airport’s geodetic control points.
- An aligned and georeferenced pointcloud for each area was created.
- Sub-sampling (3cm) and triangulation of data points was performed, followed by an optimization and decimation of the model from 3 million triangles to less than 5000 triangles, with insignificant elevation information loss.
- An elevation map (contour spacing 2cm) was generated for each area.
- Cross sections were extracted based on the above models and deformations were properly detected, measured, demonstrated and presented in table reports.
- Results have been evaluated by the A.I.A. technical department and different corrective actions have been decided for each loop area.
Results – Conclusions
Laser scanning has proven to be not only the most effective method for the project’s purposes, but in fact the only one applicable, offering the required resolution / level of detail and accuracy at a speed that was acceptable for the airports restrictions.
Related Videos
Work With Us
Need precise pavement or infrastructure surface inspection under tight time constraints? We would be glad to discuss how 3D laser scanning can work for your facility. Contact us or explore our services.
Railway tunnel 3D survey
Railway tunnel survey and structural inspection, Aghios Stefanos, Athens – Greece
Purpose
The Greek Railway Organization main railroad, to its northern exit from Athens, passes through a tunnel complex, consisting of four tunnels (two for each railway line), near the small city of Aghios Stefanos. The NE tunnel, approximately 200m long and 5m wide, was built from stones about 50 years ago. Due to suspected deformations of this tunnel in combination with known geological problems of the whole area, the Greek Railway Organizations ordered a stability check, along with a complete survey of the tunnel and the superjacent ground.
Project tasks
- Establishment of geodetic network (GGRS’87).
- TLS survey with Optech ILRIS3D:
- 8 scanning positions (6 inside – 2 outside)
- Average resolution 1-2 cm
- Georeferencing: 8 conical targets, additional control points
- Conventional survey of superjacent ground surface above tunnel.
- Basic processing of TLS data and other measurements.
- 3D modeling of tunnel and superjacent ground, H and V section extraction.
- Inspection in comparison to theoretical geometry.
Results – Conclusions
The cross-section based evaluation and comparison of the surveyed tunnel wall to its theoretical geometry revealed large deformations at specific locations (e.g. section 15). These locations have been defined and mapped in detail and repairing actions have been designed. Tunnel has been closed until repair works will be executed. Further geological investigation defined the reason of the deformations to be the presence of slate (sch) and clay (PT) formations at the tunnel’s area and the existence of a possible fault between them.
Related Videos
Work With Us
Working on a tunnel survey or structural inspection project? We would be glad to discuss how 3D laser scanning can deliver the detail and accuracy you need. Contact us or explore our services.
ECOMED Bioengineering Project
The “Specialisation Process for the Ecoengineering Sector in the Mediterranean Environment (ECOMED)” project is an initiative to advance the specialization process on landscape bioengineering, and to generate new alliances and dynamics in the sector, within the Mediterranean region. Its specific objectives are:
- To improve the design/calculation of Bioengineering Works
- To generate a suitable vegetation database for the Mediterranean region
- To improve the implementation/construction processes
- To improve the definition and planning of the monitoring of the works
- To improve the works analysis tools, to be more effective in restoration and rehabilitation.
- To improve the contents of the training offered related to landscape bioengineering
So, the EcoMed project will enhance bioengineering works at the different stages and phases: design/calculation, implementation/construction, monitoring, and education/training. This will be accomplished by implementing applied research works from 2017 till 2018. These works include the selection of a set of bioengineering tools and projects within the European Mediterranean region to further study and analyze them.
This project that is co-funded by the ERASMUS + Programme of the European Union will generate new tools to improve the possibilities of intervening in the landscape through techniques and approaches of bioengineering, taking into account the particularities of the Mediterranean region.
Overall the consortium comprises of seven universities and seven companies distributed in eight countries throughout the European region with Universidad Politecnica de Madrid the coordinator. Astrolabe Engineering is among the 14 consortium partners.
For more information on the EcoMed project please follows us through the following social media:
twitter: @ecomedbio
Facebook: Ecomedbio-Erasmus+
Road safety 3D modeling
Road intersections survey and modeling for the design and evaluation of safety improvement measures / High risk locations all over Greece
Purpose
The project was assigned by the Maintenance Department of the Greek Ministry of Infrastructures, Transports and Networks in order to improve safety for high accident risk locations (mainly road junctions) all over the Greek road network and, in particular, to design and evaluate through video simulations the appropriate improvement interventions for these locations.
Project tasks
- Selection of “high accident occurrence – reduced safety” locations by the Maintenance Department.
- Laser scanning survey, using the Optech ILRIS 3D Laser Scanner, of the road intersection area for each location.
- Alignment and georeference of the pointclouds.
- Vector drawings and orthophotos created as background for design purposes.
- Design of safety improvement interventions: additional lanes, vertical and horizontal signage, changes in traffic regulation, closure of secondary roads, etc.
- Vertical signage modeling for 3D video simulations.
- Creation of the “as designed” total 3D model.
- Video fly-through and driving simulations created and evaluated by the Maintenance Department and Local Authorities.
Results – Conclusions
Laser scanning has proven to be not only a fast data capture tool to provide accurate and complete survey background data for road design purposes, but also an easy and efficient way of creating “before / existing” and “after / as designed” colored video fly-through and driving simulations to easily compare and evaluate the efficiency of designed – proposed interventions, before their actual implementation.
Related Videos
Work With Us
Working on a road safety audit or infrastructure survey project? We would be glad to discuss how 3D laser scanning and modeling can support your design process. Contact us or explore our services.
Bridge 3D Inspection
3D inspection and structural deformation analysis of Axios river bridge at Northern Greece
Purpose
Close to the city of Thessaloniki, in Northern Greece, the Patras – Athens – Thessaloniki – Evzoni (P.A.TH.E.) Motorway, which is the main from South to North road transport axis of Greece, crosses the Axios river, one of the largest of the wider Balkan area. The crossing occurs with two long bridges, each carrying one carriageway. The southern bridge was constructed first about 40 years ago, while the northern one is much newer.
The southern bridge is 780 m long with 25 spans, built from armed concrete and has begun to show noticeable damages through time. The Greek Ministry of Environment, Planning and Public works assigned a project to check the bridges efficiency. Within the frame of this project, a complete 3D survey and deformation analysis was required.
Project tasks
- Establishment of geodetic network (GGRS’87).
- TLS survey with Optech ILRIS3D:
- 6 scanning positions (from newest bridge)
- Average resolution 2-3 cm
- Georeferencing: 6 scanning stations, 12 circular (d:50 cm) targets, additional “natural” control points
- Conventional survey for remaining details (southern side).
- Basic processing of TLS data and other measurements.
- 3D features collection (deck geometry, piers, road level, etc).
- Geometric evaluation and deformation analysis.
Results – Conclusions
To better evaluate the 3D deformations of the bridge components, the results were presented as a longitudinal section of all examined deck edges, as well as angular measurements for each pier along the 3 axis, to demonstrate possible pier rotation. The evaluation showed insignificant rotations for the piers, but surprisingly revealed considerable subsidence of all piers, except those which were founded in the river’s bottom. Different type of foundation was identified as the most possible cause for this problem. Corrective actions are being studied to prevent further damage and deformation of the bridge’s structure.
Related Videos
Work With Us
Planning a bridge or civil structure inspection? We would be glad to discuss how 3D laser scanning can deliver the deformation analysis you need. Contact us or explore our services.
Credentials & Memberships
- ISO 9001:2015 certified
-
Greek Registry of Consulting Engineering Firms, Reg. No. 681
- 5th grade: Topography (cat. 16), Transportation Works (cat. 10)
- 1st grade: Hydraulic Works · Environmental · Spatial Planning · Urban Planning · Economic · Social · Org. & Operational Research
- Technical Chamber of Greece
- Athens Chamber of Commerce & Industry (A.C.C.I.)
- HELLASCO
- Association of Geoinformatics & Cadastral Firms
- General Commercial Registry (G.E.M.I.)
