June/July 2016 No. 83 The Australasian magazine of surveying, mapping & geo-information TAKE CONTROL with industry-grade RPAS Official publication of inside Reality meets 3D World leading modelling expertise GIS of the storm Lessons from Super Cyclone Winston Locate16 wrap up Insights from the spatial event of 2016
feature When capturing reality becomes REALLY ACCURATE The hunger for accurate 3D data finds us at a point in time when reality and 3D models intersect. ANTHONY WALLACE T aking a physical reality and transforming it into a 3-dimensional model allows us to achieve more with spatial data. By re-creating reality, the products of a survey is understandable by all those who receive it, whether they are spatially skilled or not. An accurate 3D model can be just the beginning in a transformative data journey. As a result, changes can be detected, designs can be tested, and complexities can be communicated. You may be surprised to learn that a team of half a dozen from Adelaide have in recent years established themselves as the world leaders in this very kind of high accuracy 3D modelling. The line in the sand Looking at a 3D model of AEROmetrex s survey of Onkaparinga, a sea-side council area in the south of Adelaide, you could easily believe they have modelled just about every grain of sand. Within the towering cliffs of sand you can see intricate fissures from years of erosion, finger-like intrusions that defy gravity and even a long-lost street sign and garbage bin that succumbed to the ruggedness of the coastline. In some places the features are so jagged you would struggle be able to see them from either above or below the cliff line, let alone dare to access them by foot. Down at the beach, a cave is mapped deep inside with the same level of accuracy as the rest of the survey. In fact for this entire 30km coastline, every feature you can see in the model is accurate to 100 millimetres. Note well however, that since accuracies using this method are directly proportional to pixel size, theoretically the same workflow could lead to submillimetre accuracy. To study erosion at Onkaparinga, however, 100 millimetres 28 position June/July 2016 proved a capable target for just five hours of photographic acquisition and three days of ground control survey. Getting to this point was no miracle, but the result of hard-earned expertise. Using a helicopter, AEROmetrex captured some 20,000 photographs of every crack and crevasse along the 30km coastline. A ground survey of 125 ground control points placed at the top and bottom of the cliffs ensured that every feature captured was geometrically referenced. One of the people behind this undertaking, David Byrne, says surveying a location such as Onkaparinga would have been almost impossible using any other method. Byrne is the technical director of AEROmetrex and has been a strong force in the push for very high accuracy photogrammetry. By other technologies I m quite sure we wouldn t be able to get in there, he says. Most surveys especially those taken from the air are only two-and-halfdimensional. This is very much a 3D dataset- we re getting right into those caves and every nook and cranny of the coastline to create a very comprehensive dataset. It s also a fast process because we use a lot of automation, it s comprehensive in that we re mapping everything, and as a result we are able to produce a very high accuracy dataset. Byrne also says with the added dimension of photographs, this particular data extends the survey into new areas of evaluation. Typically survey data doesn t go in hand with a geological assessment, he says. But when you ve created something so realistic you can look at some of those rock formations and identify the geological structures. AEROmetrex performed city modelling ahead of the Pope s visit to Philadelphia.
The more, the better The process of taking photographs and turning them into 3D coordinates is no new feat. Photogrammetry is a term that has been in industry use since the 1940salmost as long as the commercial aviation industry has existed. Photogrammetry taking multiple overlapping photographs and inferring geometry between them has theoretically always been possible. Practically however, those wishing to practice photogrammetry have lacked the hardware and software required to perform it in a commercial setting. Enter 2016 when a decade of rapid evolution in computing both in CPUs and GPUs has allowed the development of photogrammetry software that can turn a set of photos of an object of any scale into a 3D model. Underlying this process is software called ContextCapture, a product of infrastructure software providers Bentley Systems. Originally called Smart3DCapture and developed by Acute3D, ContextCapture is the result of the acquisition of the start up in early 2015. While Smart3DCapture technology was being used by some of the world s largest mapping organisations and still is, the shift to ContextCapture seeks to open up the technology to the wider commercial market, including surveyors of all scales of operation. Surveyors became a key target soon after areial surveying was opened to the wider market following the advent of remotely piloted aircraft systems (RPAS). While data capture is useful from above by RPAS or manned aircraft, it is now also practical to perform this on the ground level using nothing more than a handheld camera. There is very little difference between capturing images from an aircraft over a city and capturing images from a UAV over a small site, says Pascal Martinez of Bentley Systems, who joined Bentley with the Acute3D acquisition. When joining Bentley our first thing was to expand ContextCapture to the entire surveying industry, he says. For readers of Position, this prompts the usual questions Is it accurate?, Is it reliable? First we need to understand that the software itself works without any coordinate information- relying only on the triangulation created from the geometry inherent in the photographs. The better the optical properties of the camera and the quality of the positioning, the better the quality of the result. However, the final accuracy comes predominately from the comprehensiveness of the photos acquired. As a general rule, the more the better. Keep in mind, however, that from the initial photography right through to the 3D model, the entire process is left is left in the hands of the software. It s a fully automated process, explains Martinez. The first part of the process is Aerotriangulation figuring out all the positions and rotations of all the photos in space. Then the geometry is extracted from the texture provided by the photos orientations. It really depends how good the dataset is that you are using as an input. Good means that photos are sharp and adapted to the desired resolution. We have encountered such a diversity of demand that we re just going out and doing it. Sometimes there isn t any direct client as such. - Mark Deuter, Managing Director at AEROmetrex. Using ContextCapture, the relative precision is 1-2 pixels, meaning that if you want to capture detail to 2mm, then you will need to capture pixels at around the 1mm level. Theoretically then, it follows that the accuracy is defined entirely by the mode of data acquisition, meaning any level of accuracy is possible- even sub-millimetre. The only thing that does restrict the accuracy is the sensor used and the way positions are geo-referenced. When you do wish to geo-reference or designate a scale, the software supports a number of methodologies. Each photograph can be geo-referenced using any combination of GNSS or IMU, including on handheld devices. Alternatively, control points can be applied within the survey to manually improve the global accuracy of the survey. Bentley Systems are also working on a way to incorporate point clouds acquired from scan data with 3D models generated through ContextCapture. It is worth noting that coordinate information is not required for each photograph, meaning that data capture can occur where GNSS observations are not achievable and that models can be created by those whose skillset includes no more than being able to take a photograph. Nor is investment in heavy computing power required, since the modelling engine is supported by the dedicated ContextCapture Center cloud-based processing service. From there, the Acute3D Viewer can also be used to share the resulting 3D model. We don t see the world as point clouds, explains Martinez. We see the world with surfaces, textures, and occlusions and that is exactly what ContextCapture is doing. People want to turn information into value. And to do this we need to be compatible with the rest of the Bentley products. The.3mx file resulting from ContextCapture can be immediately integrated into most 3D modelling, GIS, and web mapping applications, including Bentley s flagship 3D modelling software, Microstation. From there, the applications are endless. Just the beginning for AEROmetrex In Onkaparinga, AEROmetrex took a stunning natural coastline and modelled it with accuracy and a strong sense of reality. But Onkaparinga is just one of many impressive undertakings of AEROmetrex. In 2015, they were selected to perform the comprehensive 3D modelling performed for the visit of Pope Francis to Philadelphia. In planning the event, the organisers needed to coordinate with Philadelphia s public services, as well as the U.S. Secret Service. To support this, AEROmetrex acquired photographs of the entire surrounding urban landscape, using both aerial and ground-based observations. The survey informed among other things the details for the 56,400 temporary structures, main and secondary stages and event seating, 33 miles of security barricade perimeter, special U.S. Secret Service security requirements and the impact of local road closures to pedestrian traffic flows. The impressive results (see here for video: https://youtu.be/dyjd36opbmy), gained the Adelaide-based team welldeserved international recognition. For now however, AEROmetrex are focussing their efforts nationally, having started a project to capture every Australian CBD in 3D- all to 50mm X,Y,Z accuracy. Organisations of all types have shown such a strong interest in the service that AEROmetrex have made the strategic decision to begin undertaking the services on their own accord. We intend to cover every Australian city at least every CBD, said Mark Deuter, Managing Director of AEROmetrex. www.spatialsource.com.au 29
feature We have encountered such a diversity of demand that we re just going out and doing it. Sometimes there isn t any direct client as such. The applications are just everywhere. You can use it for building height regulations, you can use it as a communication and visualisation tool, you can assess visual line of site, you can perform shadow analysis. Once it s in the virtual world you can do anything with it. While AEROmetrex provide a range of surveying services, aero3dpro is the name given to their impressive 3D modelling service. And amazingly, the AEROmetrex team dedicated to everything 3D is just half a dozen people, testament to the firm s commitment to using automation. There is a lot of intellectual property in the process, says Deuter. Beginning from flight planning, through to the capture sequence, the camera used and specifically how the 3D modelling engine is used. Once AEROmetrex produce a 3D model, however, it is simply the beginning of the spatial journey for the clients down the line. AEROmetrex have used Bentley System s LumenRT visualisation software to show what Onkaparinga would look like with a new seaside development or if Adelaide s CBD was transformed by rooftop gardens. Additionally, since the data is comprehensive and 3D, virtual reality has also been used to communicate spaces in the most true-to-life format available, further empowering spatial data for non-spatial users. In this case, being early adopters has paid off for AEROmetrex. Four years ago when ContextCapture was known as Smart3DCapture, AEROmetrex were actually the very the first customer in the world. AEROmetrex is one of the earliest adopters of this technology anywhere in the world, says John Taylor, Bentley System s senior director of reality modelling. They have developed a level of sophistication in their workflow of generating models that has led to producing a very high quality product. They really push our technology to the limit. Endless possibilities In addition to AEROmetrex, the early adopters are local councils, transportation, construction, oil, gas, and mining. All of the resources sector organisations are already using this technology. This is because, as John Taylor sees it, if you can see it, you can model it, and the excitement is igniting clients imaginations. Now that this data is increasingly becoming available, the clients who will be using this data are asking how can I use it? That is a question that we haven't previously been asked, says Taylor. I see a particularly huge area of potential for local governments as it provides a level of fidelity around terrain surfaces for flood modelling, supporting engineering, site selection and design optioneering to reduce costs or predict costs long before you get anywhere near to detailed design and the subsequent delivery. What we are also beginning to see is the ability to take model data and to supplementing it with other more highresolution data from, for example, a handheld camera, and incorporate that into the mesh model to give you much higher resolution in key areas of a model. From a local government perspective, as things change they want to update the model. Councils now have the ability to have more rigorous methods to perform planning and development approval. Now they have the opportunity to take a reality mesh and compare it to a proposed design or how modifications have changed in the built environment. So there s a potentially huge local government revenue source there. Extending the ubiquity of surveying operations Despite the impressiveness of ContextCapture, scanned data acquired by terrestrial laser scanners or LiDAR will remain the best choice for many applications. Compared to taking photographs however, the data capture process for scanning can be tedious, and the acquired datasets require highly skilled, well-trained individuals in order to obtain a virtual 3D representation of reality. In contrast, producing an accurate, 3D model using photogrammetry now only requires only a camera of reasonable quality and the right software. Accuracy is derived less from technical know-how or expensive equipment, but rather from the comprehensiveness of the photo survey. Brian Middleton, Vice President of Bentley Systems ANZ explains that he does not see ContextCapture as something that will replace LiDAR: What we do with photos is just extending and advancing the ubiquity of monitoring and surveying operations, explains Middleton. The speed of doing a photogrammetry survey is far greater than a laser scan. You don t need a specialist survey team- you just need somebody with a camera. The Philadelphia skyline as modelled by AEROmetrex. 30 position June/July 2016
An oblique view of AEROmetrex s 3D model of the Gold Coast, Queensland. The final products are quite different as well, with the LiDAR data creating 3D point clouds that are complicated to work with and re-purpose into additional workflows. A photo mesh is also about 100 times lighter on the hard disk than the equivalent point cloud at the same resolution. Because of all this, Middleton sees models from ContextCapture being used not just in the design phase, but through every stage of infrastructure development by the likes of surveyors, engineers, architects and infrastructure managers. AEROmetrex were selected for their world-leading expertise and were probably one of the only companies if not the only company that could have done it. This is Australian innovation at its best. - Brian Middleton, Vice President ANZ at Bentley Systems It is an application that can be used across the whole life-cycle of infrastructure- from the design/build phase, right through to the commissioning of the infrastructure and maintenance. We re seeing models where the imagery resolution is actually submillimetre in accuracy. It means you can model small complex object as well as large complex objects at a level of fidelity that you would usually need specialist surveyors to do. ContextCapture is the only solution that combines data from multiple platforms into the one reality mesh. For Middleton, the applications are only limited by imagination and he sees it being used by the likes of road managers for slope management; police for accident forensics; miners for volumetrics; and planners for point-of-view management. The applications are endless, he says. What this can do is stop governments and organisations from performing the same data capture process many, many times during the lifecycle of an asset. What I do see is the model transcending the siloes of things like planning and development into the entire council space. This could also be the next new background graphic to all GIS. Imagery is a great backdrop to GIS, and the 3D mesh model provides a level of contextual detail far surpassing anything I ve seen before. As for AEROmetrex, Middleton says that the Australian team was the first choice for the Philadelphia modelling project. AEROmetrex were selected for their world-leading expertise and were probably one of the only companies if not the only company that could have done it. This is innovation in Australia at its best. To view the Onkaparinga coastline Onkaparinga in 3D visit: http://bit. ly/1whjrg7 To learn more about ContextCapture visit http://bit.ly/1whkwo8. To learn more about AEROmetrex and their modelling service aero3dpro visit http://aero3dpro.com.au/. www.spatialsource.com.au 31