山电话

Situated at 848 metres above sea level, the Klöntalersee inspired as early as 1655 the Zurich artist Conrad Meyer to draw the first modern high mountain panorama. Created by a rockslide ages ago and flanked by the 2900-m-high mountain massif Glärnisch, the lake is still a stunning attraction for tourists and artists due its ravishing beauty. But not only poets and painters recognised the potential of the 3.3 square kilometer large mere, which is fed by the surrounding mountain brooks like the Klön. In 1908, the Klöntalersee was impounded on its eastside between Rhodannberg and Sackberg by an earth mound to generate electricity for the surrounding villages and companies.

Due to the new 220-m-long and 21.5-m-high earth bulk dam, the lake can carry about 39.8 million cubic meters of water, which can be used to generate electricity if demand fluctuates and during peak times.

From air to water

Ingenieurteam Geo GmbH凭借其开创性的方法结合了水文和摄影测量法，计划通过使用其声音船，测量师，Leica Geosystems工业无人驾驶飞机（UAV）以及最新的定位技术来调查该区域瑞士（Leica Geosystems）在瑞士广州格拉鲁斯（Glarus）的广州。目标是生成3D模型，以精确和英寸的精确计算和对实际保持能力的模拟。

After all preparatory measures, approval processes and planning had been completed, the experts from Karlsruhe traveled with their sonar equipped vessel to the more than 220 km distant lake into the Swiss Alps to map the lake’s soiling situation at a regular water gauge. All measurements done by the vessel and Leica Geosystems UAV were recorded in the Swiss national coordinate system LV03.

With 172 planned recording lines, the 6-meter-long vessel set sail to create a detailed picture of the lake’s soil using its Reson SeaBat 8101 Multibeam echosounder. The fathometer emits acoustic signals at an angle of 150 degrees and calculates the depth of the water by measuring the elapsed time of the echo. At 101 beams per ping at a frequency of 30 pings per second, the hydrographs receive high-precision data of the bed with a graticule of 3,030 single points per second. With an overlap of one-third of every measuring track, the experts ensure that an accuracy of less than 10 centimeters is achieved during their measurement.

But before data can be gathered, the measuring system must be calibrated precisely in order to avoid disturbance factors and to correctly determine the results. Therefore, the sensor technology must be adjusted before every deployment to subtract both linear movements of the vessel as well as rotation around its axles to impede any falsification. A further step for the hydrographs to get a clear and detailed view of the lakes ground is to factor the waters sound velocity into the calculation, which changes depending on temperature and suspended particles and becomes especially important in lentic water.

船上有启动和校准后,crew put out to sea on a two-and-a-half hour long first cruise to get a first impression of the lake’s character and began to create the first sonar data of the soil. Following the planned routes and under consideration of the lake’s depth and texture, the highly skilled hydrographs on the Surveyor collected enough information to create a point cloud of 134.837.653 X-Y-Z-coordinates. All in all, the crew of the observation boat made it in five days to record all 2,855,204 square meters of the Klöntalersee.

Beyond limits

不仅快速多变的气候条件和好的e-chilling cold pushed man and machine to its limits, with the glaciated massif Glärnisch building the south embankment, the environment put the technology to the test. With its 2,900 m, the massif literally threw its shadow ahead. Through the massifs steep slopes in close vicinity to the riverside, the experts feared they might lose their GPS-stream due to signal opacity on the south side of the Klöntalersee. In this case, the determination of the boat’s position would have been carried out by tachymeters placed on the northern and eastern shore of the lake. Because of the lake’s long-drawn-out kidney shape, this would have led to serious problems to get accurate details of the boat’s position.

By using the Leica Viva GS 16 GNSS antenna on the Surveyor, the data recorded with the multibeam sonar could be assigned inch-perfect to their coordinates. With its built-in SmartLink-technology, the crew would still have been able to record high-precision data and receive the GNSS correction data even if the signal of the GSM network would have gone missing. Thanks to 550 channels, a state-of-the-art surveying engine and ultramodern RTK algorithms, both the data of the UAV and the vessel could be precisely assigned to the test results.

Due their general design, bank situations are hard to capture for multibeam equipped vessels. In addition to that, the risk of damaging the sensitive and expensive sensor rapidly rises in shallow water and in the proximity of the shore. In order to still obtain exact results for the volume calculations and simulations, the engineers relied on their experience with their UAV and decided to capture the shores and embankments airborne via photogrammetry.

天空的精度

After the lake was measured at regular water level from the boat, the engineers began to plan the flights for the Leica Geosystems UAV solution. To capture the shore regions overlapping with the measurements taken by the boat, it was crucial to plan the following flights with the UAV at lower water levels. After the level of the Klöntalersee had been lowered seasonally, the survey with Leica Geosystems hexacopter began.

为此，ING的专家。Geo的专家计划使用内部建造的飞行计划软件，为以下航班设置航路点，并确定适合调查的参数，例如高度，地面采样距离（GSD），数据速度和数据重叠。为了尽可能准确地记录银行区域的倾斜和陡峭的地形，专家决定多次调查每个区域以提高数据的有效性。PC上的飞行计划完成并将航路点加载到UAVS内部存储空间后，使用Viva GS16测量了湖泊周围的地面控制点（GCP），因此可以开始首次飞行。

Once again, the surveying of the alpine reservoirs presented its very own challenges for man and machine. In addition to average temperatures of less than 0 degrees Celsius, rapid weather changes and low clouds, once again the southern bank of the Klöntalersee with its steeply sloping mountain walls was the biggest challenge. The UAV had to be started and landed on a separate boat because the steep walls and the dense vegetation of the shore made it impossible for the pilot to operate from the land. In addition to the sensitive and reliable technology, the skills and the steady hand of the pilot were particularly important.

尽管有不利的条件，但来自卡尔斯鲁赫（Karlsruhe）的团队还是能够在18次飞行中收集高度精确的数据，因此在两天内覆盖了总长度超过12公里的干岸条。每两秒钟拍摄一次图片，而无人机则以4 m/s的速度移动，专家们确保了数据以最高准确性记录到飞行多传感器平台上的相机。

“Due to the fast data availability of the UAV, we were able to evaluate the first results on site,” said Benjamin Busse, IngenieurTeam GEO.

Combining technologies with accuracy

As with the recordings of the surveying boat, it was of immanent importance for the UAV-based results to accurately reference them. For this purpose, the experts of the Ingenieurteam GEO equipped the UAV with an special RTK / GNSS module and used in addition the Viva GS16 GNSS antenna, which was the perfect match to work under these difficult conditions to achieve an accuracy of 1-3 cm in georeferencing the collected data.

After all measurements had taken place, the surveying experts began to process the obtained data. The point clouds created by the multibeam sonar had to be fed into the PDS 2000 bearing software to manually edit and correct them from imprecision. In order integrate the data of the river banks into the volume calculation, all 4,400 high-resolution images created with the UAV had to be imported into flight planning software, where they were merged with the coordinates from the UAV’s log file. After that, the georeferenced data was edited in the post processing software AgiSoft PhotoScan Pro to create a 3D model as well as a point cloud. Subsequently, the two 3D models were combined in the Autodesk application AutoCAD® Civil 3D to generate an exact model of the lake's situation.

Using the data from the 3D model, the engineers generated a precise map with elevation lines for their client. By being able to generate such a precise result and to combine two completely different ways of surveying large and challenging areas, the engineers stood up to the game and used the most modern technology to get the job done. With the data generated by boat and UAV, the experts are able to fulfill their clients’ wishes of a detailed virtual 3D model and a metres long situation plan with contour lines printed out.

“The combination of the measurement results of our modern multibeam system and Leica Geosystems UAV allows us to generate high-precision data very quickly,” said Busse.

Leica Geosystems再次选择飞行多感官平台来重新考虑传统的工作方式，是专业人士取得最佳成果的正确选择。