When every millimetre counts

Author:塔玛斯·萨法尔（Tamas Safar）

When thinking of common laser scanning applications, capturing intricate 3D objects or structures comes to mind. Flat, dark surfaces, just like the asphalt of the Zalaegerszeg test track in western Hungary, do not escape, however, the realm of High Definition Surveying (HDS). A 3D smart digital reality of this unique proving ground was created to ensure the track offers driving stability not only for conventional automobiles, but also for autonomous vehicles and electric vehicles.

With the Zalaegerszeg Automotive Proving Ground, Hungary provides an unparalleled venue with the highest standards. The world’s leading automotive companies, research teams and universities, will test here from breaking systems, running gears and tires to onboard navigation systems; as well as testing self-driving vehicles in an especially urban-built environment.

HDS professionals from Hírös Geo Kft assessed the quality of the pavement structure and flatness by analysing 3D point clouds generated by laser scanning.

Point clouds for pavement

Engineering teams need to produce the best possible quality pavement with an even surface so teams can trial automobiles. The dynamic platform is the area of the test track system where the cornering grip/slip friction and overturning stability of the self-driving vehicles incoming at high speed will be tested. Hírös Geo Kft, a Hungarian land surveying, engineering and utility geodesy company, was commissioned for the quality control of the 10 centimetres thick asphalt base layer of the 300-metre diameter circular dynamic platform.

准确性要求非常严格 - hírös地理kft需要证明，沥青基层的顶表面仅在其任何测试点上相对于计划的平面表面偏离少量毫米。

Hírös Geo Kft chose terrestrial laser scanning to measure the asphalt deviation. The specialists carrying out the measurement presented the divergences from the measured surface in the nodes of a regular 2 cm x 2 cm grid covering the dynamic platform. All measurements fitted to the Hungarian Unified National Projection measuring coordinate system.

Using the Leica ScanStation P40,该地区的详细调查包括70,650平方米，度过了整个工作日。单个设置产生的高质量数据，对应于计划的采样密度，在激光扫描仪周围40米的半径内。通过使用Traverse测量方法收集48个设置并链接。这导致了大约3D点云3.45 billion measure points。Point clouds were evaluated in the Leica Cyclone REGISTER software after a basic cleaning process.

“通过传统的测量技术进行控制测量是不可能的。ScanStation P40为我们提供了自由和灵活性，可以生成所需的数据数量，直接缩放到项目要求，”said Barna Bodri surveying specialist at Hírös Geo Kft.

像皮带一样平坦

The high-precision registration of the setups was perhaps the biggest challenge. The process could not be assisted by the 3D point cloud post processing software’s recognition of “identical surfaces” (auto-alignment and visual alignment of the point clouds) because the asphalt is a monotonous, flat, dark surface without any points of orientation. Instead, black-and-white targets above the ground control points enabled the registration to be globallyaccurate to 1.8 mm。

评估数据明显显示上surface of the asphalt layer has a match of nearly 90 per cent, provided that the deviation of the measured points cannot be greater than a few millimetres to the best fit plane. To lay the asphalt layers, operators relied on the Leica iCON iGG3 to guide the grader with precise control of the blade. Thanks to the 3D coordinates, it was easy to define and stake out in the field which areas need milling before the binding layer was placed. From here, the milling is an easy process using automated iCON machine control.

匈牙利土木工程公司的专家关注的目光是建造汽车验证的地面是存在间接的带状伸长率的迹象，这与特定公差以外的地区的旅行方向平行沥青轨道的边缘相遇。散布时，突出的表面与沥青的温度有关 - 当连接带沉积在升高温度下时，已经放置的沥青轨道已在冷却阶段处于冷却阶段。连接表面之间的温度差异越高，道路辊使连接平稳的困难越困难。

创建数字现实

bob综合app赌博现实捕获使匈牙利的HDS专家能够通过3D地理参与模型来衡量和验证表面均匀性，从而优化施工工作流并在现场和办公室之间进行数字共享信息。

Based on the presented useful information, experts优化了他们的工作流程并减少了所需的时间和成本to achieve quality work most effectively.