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Network Rail Bathymetry survey River Calder

Whalley Viaduct Following on from the initial successful 3D terrestrial scans of Whalley Viaduct. Network Rail requested an additional Bathymetry survey of the river bed, to investigate any potential issues. The Whalley arches are important components of this busy railway route built between 1846 and 1850. One feature of the viaduct is that it not only traverses land for much of its length, but also crosses the river Calder. Bathymetry To ensure the viaducts integrity in the river Calder section,  a bathymetry survey was undertaken. A 100m section of the river was mapped using a HyDrone RCV remote control survey  platform. The HyDrone RCV was connected to a GNSS receiver. Adding the GNSS receiver, enables points on the river bed to be accurately geo-located. Using the data from the GNSS assists with the building a 3D model of the river. In addition, the receiver was linked with a LIDAR survey of the riverbanks to enable the accurate profile build of the river under the viaduct.  Monitoring erosion and scour Monitoring the riverbed around the structures is a critical undertaking. The principal mode of viaduct base failure is typically focused on the area where flooding and scour occurs. Flooding, climate change and increase of rainfall significantly change river hydraulics and, in some cases, it can cause serious problems to the base of structures. This survey concentrated on riverbed scour, identified using our high-resolution sonar bathymetric remote-control boat. Data Collection Using our bathymetric underwater surveying technology gives our engineers the ability to inspect water retention and riverbed features using specialist software back at our base. The data we collected from the watercourse characterises the river both above and below the waterline at the River Calder location. Additionally, we visualised the impact of objects affecting river flow and evaluated the changes in the river caused by sediment dynamics. The comprehensive bathymetric data captured the above features with a precise resolution and detail. Consequently, the inspection and assessment of the viaduct features and improved sonar detail increased the evaluation of the watercourse. Thus, ensuring safety of the structure by identifying any areas of concern. The models provided will be used to assess future maintenance requirements and to ascertain any immediate works required. 

Scanning with Network Rail – Scans, drones and viaduct arches

Whalley viaduct built in 1846 stretches across the river Calder. The viaduct is a magnificent structure, consisting of 49 brick arches, 620m long and 21.3m high. Locally the area is known the Whalley Arches. Traditionally, the surveying and inspection of these structures would be undertaken manually, with measurements and repetitive paper-based data entry. The traditional method is both time consuming and expensive; requiring extensive scaffolding. To eliminate the human errors attached to traditional surveying, and to save on time, we employ terrestrial 3D laser scanning techniques to capture buildings and structure data. Combined with photography of the structure, the laser scan data assists in assessments, helping with the prioritisation of maintenance issues,which may or maynot be required. Our team travelled to Whalley Arches late in the evening, our job was to scan the top railway section at midnight, the best time to work when scanning railways - whilst trains were stopped. However, due to strong wind gusts and torrential rain, the night time scan was cancelled much to our dismay. Undeterred, the next morning, clear skies and a mild breeze greeted us as we set off with a RIEGL scanner, two drones and camera team to capture the arches. Several areas under the arches required cleaning out of saplings, brambles and general discarded waste. These were cleared by the ever helpful team from Network Rail, armed with Chainsaws, and industrial hedge trimmers. As soon as these obstacles were cleared, giving us line of sight for the scanner and operator and easier access to the grounds, our job commenced. Each arch was scanned with terrestrial lidar, which made for some interesting scrambling up embankments and into residents gardens to ensure a clear view of the arches for the scanner. Thanks to all the residents who allowed us into their property, who were all very kind and welcoming. A total of 187 scan positions, combined with 3,000 high resolution photographs gave us a highly detailed accurate comprehensive analysis of the complete structure.

Practicalities of 3D scanning

3D scans useful in so many ways Our forte is our ability to combine data from the following different sources and technologies: Sonar, Bathymetry, LiDAR, and Photogrammetry. Promote your service with an exciting 3D interactive film or animation, or accurately measure your buildings or terrain. For speed and accuracy of capturing geospatial data, such as buildings, bridges, objects, and terrain. We give you asset management, 3D virtual films and surveys, and promotional marketing services too. The benefits of using our services are twofold “accuracy and speed.” 3D cameras vary in specifications; they are expensive and complicated to use regarding downloading and stitching the collected 3D data images. With our service, you tell us what you want and we do the work for you, from travelling to the location, capturing the data, processing your data, and passing you the finalised product. Our scans are precise to submillimetre distances, and can be used in a variety of scenarios, from forensics to wind turbines, terrain and building structures. Most recently we have been making 3D animated films to assist the tourist industry and engineering companies. 3D scans take your Quality control and quality assurance workflow to the next level of speed and accuracy. We quickly and accurately collect, process, and deliver your data even in hazardous and demanding conditions. Our data provides you with the ability to process, manage and collaborate more efficiently with greater detail. In addition to measuring benefits, your 3D data lends itself to immersive film and fly throughs giving you total “ real time” experience and clear views of your buildings, installations, and terrain.

Surveying and scale plans in 3D illustrating speed and accuracy in Forensics

Traditionally forensic tools consisted of cameras, to take photos and videos and measuring tools, tape measures and measuring wheels. The problem with the traditional method is that it is a complicated and time consuming process. Time and complexity are not helpful when collecting information as quickly as possible. In traffic accidents, with fast moving and changing environments and crime scenes where deterioration of the scene can happen very quickly. Scanning is invaluable for capturing the scene quickly. To enable the fast and accurate collection of data there is a vast array of geospatial tools to capture vital forensic evidence and information. This information is helpful and can be relevant in court or for insurance purposes. 3D Surveying and scale plans illustrate accidents and crime scenes as pristine views of what exactly occurred. The 3D scans offer the ability to capture precise measurements, and record everything for prosperity and for further thorough analysis. Using multiple scan stations, and line of sight positioning of the scanner, we obtain every detail in perfect 3D precision. Dependent upon the type of scanner used, and your requirements, our Scans can be viewed in real time or taken away to be compiled, processed, and delivered to you; in which ever format you require. Scans lend themselves to measurements from every angle, allowing for clear and precise forensic information. Scans can easily be viewed as a walk-through; this Provides both inspectors and a jury insight into the scene that was not previously possible. Our 3D survey and scale plans are presented in colour, which adds to the immersion of the scene itself, and assists with both spatial and visual referencing of event. Our 3D captured models bring not only speed of delivery, but clarity and understanding to all your scenes.

Riegl scan to 3D film – The process

A glorious film project landed on our desk at the beginning of December. A mixture of photogrammetry, a LIDAR Scan, and drone footage. The task: To take all the above, fix, remodel, and turn the resulting 3D objects into a film. We had collected data earlier in the year when we visited the cave in winter to gain the advantage of low water levels and sparse vegetation. The first model, created by drone, using thousands of aerial shots was of the entrance dolines, huge depressions in the ground, along the bottom of which the River Reka flows before entering the caves. The second model of the cave, a stupendously huge file, created using a Riegl Vz-400 terrestrial scanner converted to a single 3D point cloud. Upon opening the resulting point-cloud, it presented itself as perfect, but consisted of four million polygons, which meant slow processing even with our high spec computers. First task, the model had to be decimated, bringing it down to a manageable size. The model, an exact replica of Škocjanske Jame, one of the largest known caves in the World, started out in magnificent detail. The decimation was handled carefully, a fine balance was required, to reduce the size and maintain the exquisite details captured by the Riegl scanner. Once the model was decimated, it was time for a thorough inspection. As we delved inside the cave, it felt like virtual caving, as the camera twisted and turned through the labyrinth of passages. Working one’s way around a cave system in 3D software can be quite disorientating, even when it is one of the largest in the world. The second issue presented itself while working our way through the caverns. We found areas of the model that were blank because they had been hidden from the scanner; it is quite impossible to place the scanner in all the positions required to capture everything. We solved this by digitally creating realistic walls, under the guidance of our own expert caver, who has first-hand knowledge of the cave. Once the erroneous areas had been cleared, the next task was to texture the cave. Due to the sheer size of the cave, it is impossible to capture the textures, as one would with photogrammetry. Using photographs taken from sections of the cave, our art department created bespoke images to be used as textures. This is a tricky task, because all…

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Surveying a Water Pipe

It was with some trepidation that Commendium accepted the challenge of surveying an 800m long 0.9m wide water pipe in North London. Being underground, without the aid provided by GNSS and capturing surrounding furniture, surveying a metal pipe must pose the most challenging subjects for LiDAR as there are few clues in the data to assist with the registering and alignment of scans. We set about this by mounting a VZ-400 into a crawler provided by the Water Services Group and set up a process to take scans at every 3m through the tunnel. We supplemented the displacement measurement by using an IMU to measure orientation and displacement between scans as precisely as possible. Scans were taken manually by connecting the scanner to the scanner via a fibre optical link, which via ethernet switching also allowed us to capture photographs and video at the same time. Back on the office, the scans were realigned using data from the IMU and then brought into RiScan Pro for manual, fine stitching using the MTA tools. It was vital to prevent roll and pick tie points from small imperfections in the pipe revealed by the scanners. There was no way around this slow manual process, but the results were excellent, a tribute to the quality of the core Riegl LiDAR technology. We ‘closed the survey loop’ by surveying over the surface to the other end of the pipe, this time enabling auto-registration as GNSS and plenty of street ‘furniture’ was available to stitch scans. In the end the loop closure was just under two metres over 1.8km; that will do nicely. The survey was able to show in detail four additional anomalies that were unknown to the client engineers. Had these not been identified, it could have rendered planned maintenance ineffective. It did mean that additional access had to be dug to address issues, but this remains hugely less expensive and time-consuming than the alternative.

How to Combine Drone and LiDAR Survey Data

In this article, I will attempt to give an overview of how we combine Drone and LiDAR survey data, via point clouds and other means. Everyone has a different method of doing this, depending on the software at their disposal, but this is the process that works best for us. Why combine the data? There are a number of reasons a project requires a combination of Drone and LiDAR point cloud data. In our case, we use a terrestrial LiDAR unit  along with aerial photogrammetry. Sometimes, the shape and height of an object means we cannot get the LiDAR device to scan the top of the target. In other cases, the area is too large to simply survey with a terrestrial LiDAR unit. An example project is a recent project to scan an old farm and it's surrounding landscape. The farm was in disrepair and needed internal and external surveying. As it was built on a glacial drumlin, the surrounding area also needed to be included. Our method was to survey the buildings with the terrestrial LiDAR scanner and then combine this with a point cloud created from an aerial survey. This point cloud would then be used as a guide to draw a detailed Autocad Revit model including the topography and buildings. Drawbacks of this method The main drawback of this method is that we are combining two datasets with differing point cloud densities. The terrestrial LiDAR survey has a point cloud density in the thousands per square meter, whereas the drone photogrammetric survey has a density of nearer the hundreds. This is not generally a problem if we understand that the two methods have different uses. It is also tough aligning two point clouds created with different hardware and algorithms. This is where accurate GNSS survey data becomes essential. [gallery size="medium" ids="7015,7014,7016"] The importance of GPS and Control Points. The importance of using accurate GPS co-ordinates and ground control points / targets cannot be understated here. If you have a wide range of effectively placed targets that are visible in both the drone survey and the LiDAR point cloud, it makes combining the two datasets immeasurably easier. There will be errors and there will be a slight difference in figures, but the more accurate you GPS control points are, the lower the error rate, ensuring the resulting combined dataset is still within accuracy limits. We use a combination…

3D Laser Tunnel Survey – Wet and dry.

3d Laser Tunnel survey; wet and dry Laser scanning methods have been in use for several years to survey objects, buildings and tunnels and the level of detail that can be obtained is stunning. It allows for wide range of inspections to be completed including, mapping, surface condition assessments, over and under breaking analysis, component inspection and relationship to surface features or activity. There are two approaches: a handheld laser unit or SLAM (Simultaneous Localisation And Mapping), or  terrestrial LIDAR (Light Detection And Ranging) unit; both have their advantages. A hand-held SLAM is rapid and will go places that a LiDAR unit cannot, so is preferable in long or small tunnels, but it cannot capture the detail that a LiDAR unit can, which is a slower more considered approach. Commendium will use the most appropriate method for any job and typically uses a blend of technologies to gain the desire output. With partners, The Water-Services Group, we are able to offer a multi-technological approach to surveying tunnels, aqueducts or aquifers. Uniquely, with software built in-house, we are able to combine and synchronise SLAM, LiDAR, Ground Penetration, Sonar and Airborne survey data into complete 3D models of underground subjects, so that, for instance, we can create a geolocated map of a tunnel, accurately assess the depth below ground of a tunnel at any point on the surface, accurately measure spatial relationships between underground features and give a detailed, even forensic, 3D condition survey, a full 3d laser tunnel survey all in dry and partially or fully flooded systems. We can survey where humans cannot venture using robotic vehicles, but also have the necessary confined space, access, and safety training to physically venture into these tunnels. We have recently been testing these combined technologies in Speedwell caverns in Derbyshire. Here a stairway leads to a boat ride along 450m of half-flooded tunnel, meticulously mined out in the 1770s, to a large chamber. We where able to combine sonar data from underwater, SLAM data long the tunnel and high quality LiDAR data in the chamber at the end, into a single 3D dataset.

Does my BIM look good in this Software?

  3D BIM data delivers some wonderful awe-inspiring models and structured information, but it can be a confusing medium to work with due to the huge array of outputs 3D has on offer. 3D data output comes in various formats from point clouds to intricate geometry. These different formats and outputs are where things start to get complex. Sometimes it is hard to know where to start or what exactly you require from your scan data. The 3D road is beautiful but converting 3D files can eat into your time like a ‘boxset on a bank holiday’. With the AEC industry often tarnished by problems such as growing costs, and project overruns, wastage, and inefficient processes, sorting out your BIM workflow is critical. Getting the right 3D We are all aware that it is relatively easy to do an ‘ok’ job, but it is much harder to deliver a perfect one. Getting the Software right can be a big issue, it is expensive, takes a lot of investment and training to learn; and not one piece of software is perfect for every job. Each 3D job may require an array of kit, software, and peripherals. The choices you make are dependent on the industry you work within. For example, Revit is widely used for BIM, but there can be unique and specific requirements to BIM that require different software. We all know that each sector has its own favourite 3D file software and formats. These choices are driven by the tools used in each sector, which is great, everyone loves a workflow that is smooth and fast. However, sometimes software is used for historical reasons, by this we mean, it is the software the company has used for years and that is just the way they work. Again, whatever works for you is good, but the problems start to emerge when one company works with another, and the combined pipelines must work in harmony. Sticking to what you know v using the right software for the job Software makers have their own file format, which is optimised exactly for their software. Mistakes may occur when choosing which option to use when saving or exporting a file. For example, do you want those CAD files saved in ASCII, Binary, or Compressed Binary? Using neutral software goes some-way to help workflows and improve interoperability. Nevertheless, there are often niggles with changing formats.…

Drain the Oceans: Thai Cave Rescue – A Nat Geo documentary

As a result of our numerous cave scanning assignments, Commendium were contacted by MSP TV to assist them with an episode of the ‘Drain the Oceans’, a series on behalf of Nat Geo TV. Having worked for The National Geographic on several occasions, it was great to be back working on Drain the Oceans: Thai Cave Rescue.  Our brief was to 3D survey a 6km stretch of the Tham Luang cave passages in Thailand, using LiDAR terrestrial scanners. The data from the scans would be processed to make a photorealistic CGI 3D model of the cave journey. The 3D model itself illustrates part of the Thailand Cave Rescue story deep in the Chiang Rai province. Prior to setting off we were looking at a hand-drawn cave survey of the Tham Luang cave system, completed by its first explorers. Looking at the illustration it was immediately clear that this was going to be one of our more demanding projects, 6km of often narrow, invariably humid and muddy cave passages. We estimated it would take three weeks, to scan the caves and a complete surface survey of the area. The Challenge The cave system proved to be every bit as challenging as we had imagined. In the dry sections, the cave was very easy to navigate for experienced cavers, however, then came the slippery section with lots of clambering over large boulders. With each of us carrying about 20kg, the humidity was draining for the crew. We opted to scan from the furthest point inside the cave and work our way through to the entrance. This was mainly for psychological reasons, for every subsequent surveying day required less travel to the start and so became easier, though most days underground were more than ten hours. One job was to record the cave texture through photography. It is amusing to put one of the world’s leading caving photographers to such repetitive work, but the discipline to ensure that everything is recorded meticulously is probably the single hardest aspect of 3D data capture. We tried to work to three days and then rest on the fourth, however, in practise, our rest days and evenings were spent processing the vast amounts of scanned data. Our drone operator meanwhile was travelling above ground capturing the surface terrain data. Capturing Data By the end of the project we had gathered almost a terabyte of data, which takes some managing,…