Construction World June 2021

CIVIL ENGINGEERING

INTEGRATING AERIAL SURVEYS, LASER SCANNING AND 3D MODELLING TECHNOLOGY Bosch Munitech and Bosch Projects – part of the Bosch Holdings group of multi-disciplinary consulting engineering companies – offer specialised services that encompass aerial surveys, laser scanning and 3D modelling technology, to enhance engineering projects.

including multispectral imagery for irrigation planning and stockpile, topographic, as-built, LiDAR and infrared thermographic surveys. We also use aerial surveys for GIS mapping and analysis solutions, as well as pipeline and road route pro ling, water ow and drainage design. Advanced UAV and camera technology enable drones to utilise cameras that deliver high-resolution images and videos. Data is safely captured in compromised, dangerous and sensitive environments, with minimal risk to the surveying professional piloting the drone. With the skills of an experienced pilot, drones can easily access towers, masts, roofs, tall buildings and wind turbines. Another benefit is that large areas of land can be covered in a short amount of time. Pre-planned ightpaths also reduce the time taken from initial planning, through to the nal data processing and end-product delivery, which is important in time-sensitive projects. The process of photogrammetry from a UAV uses photographs from at least two different vantage points. Depth and perspective are calculated based on the varying angles of observation of the same points of interest. Using advanced software, hundreds of overlapping images from different angles are processed and thousands of points are identified on two or more photographs. The software algorithm then finds the geometric intersection of the light rays and calculates where that point is located in 3D space. The software deciphers camera locations, angles and characteristics resulting in the creation of millions of accurate points in 3D space. These points are then converted into topographical surfaces and texture-maps, providing a complete and accurate digital replica of the site. The Bosch team has used drones for aerial surveys in combination with 3D modelling technology, in several recent projects, including sugar factories in South Africa and South America and a wastewater treatment plant in East London requiring refurbishment work. The Mdantsane Wastewater Treatment Works (WWTW) project was constructed in the early 1970s and no drawings or blue-prints could be found for the works. Bosch Projects was awarded the contract to develop new as-built drawings of the existing works and to update these when required. To obtain detailed site information required to reproduce workable as-built drawings, the team used safe and cost-efficient 3D-scanning methods for the buildings and aerial survey scans for creating a digital 3D-terrain model that is being used to simulate stormwater run-off, which poses a concern for the client. This study is currently underway. There are many advantages of utilising geospatial technology, including time efficiency and enhanced safety. With this system, there is no need for repeated site visits to verify information and the risk of exposure to dangerous fumes and vulnerable structures is removed. 3D-scanning, which is incorporated into civil design packages, allows advanced calculations to be quickly and accurately completed. Clients are able to view 3D-Illustrations virtually and problems can be identified before construction commences, without having to physically visit the site. Parts and equipment can be easily changed and moved around, eliminating the need for incurring labour costs. Bosch Holdings has utilised aerial surveys, laser scanning and 3D modelling technology successfully for many years, to ensure accuracy and efficiency of engineering deliverables. ▄

“O ur highly-skilled team, with specialist partners, utilise unmanned aerial vehicles (UAVs or drones) for aerial surveys, often in combination with laser scanning and 3D modelling technology, to provide our clients with quick, accurate and relevant data,” explains Andrew Cruickshank, Operations Director at Bosch Holdings. “The use of drones significantly extends the capabilities of aerial surveys that have traditionally been conducted using terrestrial, light aircraft or helicopter surveys. Bosch has made a substantial investment in laser scanning that uses the latest technology for detailed measurement purposes, to create topographic maps, meshes, point clouds or drawings, based on the real-world. “Our specialists efficiently capture high-resolution imagery, using a technique known as photogrammetry, to create a comprehensive list of deliverables required in engineering projects. This data, which is becoming increasingly popular within the global surveying and engineering sectors, includes a dense 3D point cloud, orthomosaics (detailed distortion-free photographs of a site), digital surface models (DSM), digital terrain models (DTM) and topographic contour maps. “Benefits of using UAVs or drones for aerial surveys include accuracy, safety for operators and accessibility to difficult locations. This technology also enables quick and efficient data capture, cost- savings and the flexibility to deliver various aerial survey outputs,

CONSTRUCTION WORLD JUNE 2021 32