uav + surveying
Laser scanning technology tested Surveyors challenged to gather accurate data on 900 buildings in two weeks in winter. By Erik Dahlberg
Surveyors use the Trimble SX10 in Changchun, China. They could scan eight buildings in one day.
Nine hundred buildings in two weeks — in biting cold — grabbing data down to 5 cm or better. It would be a daunting task anywhere, but especially so in the harsh winter of China’s Jilin province. In Changchun, Jilin’s capital and largest city, local authorities are responsible to maintain and improve city structures. Part of the effort includes a long-term project to improve insulation, provide maintenance, and improve the exterior appearance on a large block of buildings in one section of the city. The city’s plan to repaint exterior surfaces called for detailed measurements of the building façades — accurate to 5 cm (2 inches) or better. To achieve that level of accuracy, the city called in Heilongjiang Star Survey and Mapping Technology Co., Ltd. (Star Survey) to collect the required information. Speed in the field Field work began in December 2016, just as the harsh Jilin winter set in. The Heilongjiang surveyors were given barely two weeks to gather accurate data on all 900 buildings. Faced with the tight schedule, Star Survey knew that standard surveying wasn’t fast enough to capture the needed data in the allotted time. Instead, the company turned to laser scanning for data acquisition. In addition to conventional scanners, Star Survey put an important new technology to the test. Star Survey assigned three survey crews to the project and equipped one of the crews with a Trimble SX10 scanning total station.TheSX10combines the functionalityof advanced robotic total stations with precise, high-speed laser scanning. Used in conjunction with Trimble Access software, the instrument uses built-in cameras to collect high-resolution images of the scene and enables the operator to “see” through the telescope via a virtual display on a rugged tablet. Over a 10-day period, the SX10 completed detailed scans on 80 buildings. By leveraging the instrument’s long range, the two- person crew could typically capture an entire building façade from just one setup. When additional setups were needed, the crew used the SX10 surveying functions to tie setup points
Plan view of part of the project shows the multiple setups required. The SX10 could tie the setups together to reduce office processing.
Examples of raw data (top) and finished elevation in Trimble Business Center. Results could be exported to standard CAD software and formats.
Technicians blended point clouds and images to produce 3D visualization of Changchun buildings. The image includes locations of SX10 setup stations.
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march 2018
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