3D photogrammetric survey by drone of the largest hotel in Malaysia
Hélicéo and its Malaysian distributor Skyshine make a photogrammetric survey of the Putrajaya Marriott Hotel Palace. Today, this is the largest hotel in Malaysia. It is built in the heart of a green setting of more than 100 ha (247 acres). Putrajaya is the new administrative capital of the country.
In April 2018, Dr. Haixing (Hélicéo Asia Director) and Sébastien (Hélicéo Engineer) begin their one-week trip to Malaysia. After 16 hours by plane to Kuala Lumpur, they discover a modern city, populated by skyscrapers and more than 1 600 000 inhabitants. Despite the time difference, our two travellers quickly take the road to go to the mission scene 25 kilometers away. On the way, the landscapes are very different with hills and forests for as far as the eye can see.
On the spot, Dr. Haixing and Sébastien receive a warm welcome and discover a local exotic fruit with a very particular smell and taste: the durian. Then, they present the upcoming mission context to around forty surveyors.
Two drone flights for one photogrammetric mission
The 3D reconstruction of the Putrajaya Marriott Hotel
The photogrammetric survey is carried out using two drones from the Hélicéo range: the FoxyPro, a 3.20 m wingspan VTOL aircraft and the SuperFox6, an hexacopter drone. These are complementary because they have been designed for different applications. Indeed, the Foxypro is a vertical take-off and landing aircraft (VTOL) which scans large areas of up to 300 ha (741 acres) in a single flight. For this mission, it surveys nearly 100 ha (247 acres) around the hotel.
However, to collect the facades and constructions details, the SuperFox6 is used. This multirotor inspection drone has 43 minutes autonomy and 55 km / h wind resistance. Thanks to the collected data during these two flights, it is possible to reconstitute the hotel and its green park in 3D. Dr. Haixing and Sébastien obtain a very dense, complete and georeferenced point cloud from 346 images. This point cloud generates a high resolution orthophoto with 3.93 cm accuracy.
• Size of the project: 80 ha (198 acres)
• Cumulative flight times: 20 minutes
• Flight height: 180 m au-dessus du sol
• Ground resolution (GSD): 3,93 cm
• No GCP is needed
• Temperature: 40°C
• Number of images: 346
• Software: Hélicéo HASK and Pix4D
• Data processing duration: 5 hours
The VTOL, the indispensable innovation for flights with reliefs
This mission is complicated because Dr. Haixing and Sébastien must take off drones in a very small area between two mountains. Indeed, Malaysia has a very hilly environment which gives the VTOL technology an undeniable advantage. In addition, lush vegetation is a strong constraint as it prevents the use of landmarks or ground targets. In this context, the GNSS RTK (real-time kinematic) technology with the Hélicéo HASK processing software is indispensable. Indeed, HASK allows to increase RTK accuracy from 15 cm to 4 cm.