SYNCHRONISATION OF DRONE BATHYMETRY, LIDAR & PHOTOGRAMMETRY SURVEY APPROACHES TO STUDY THE EMBALSE CONDE DE GUADALHORCE RESERVOIR IN THE MALAGA REGION, SPAIN

We are pleased to share the results of the first drone bathymetry and LIDAR survey project in Spain, carried out in collaboration with a leading drone service provider and TOPODRONE reseller in Spain - Atyges (www.atyges.com) and Gonzalo Malvarez from the Costal Environments research group of the Universidad Pablo de Olavide de Sevilla.

In the hardware part, we used DJI Matrice 300 drone, TOPODRONE AQUAMAPPER, LIDAR 200+ and P61 high resolution camera. In the software part, we planned missions in the UgCS software by SPH Engineering and processed data in TOPODRONE Post Processing software.

As the first step, TOPODRONE AQUAMAPPER was connected to a DJI M300 drone and several automated flight missions were performed in PPK mode to collect the set of bathymetric data (water depth, temperature, GPS position&inertial data).

Fig. 1. AQUAMAPPER connected to DJI M300 drone for bathymetric survey.

Immediately after the flights, all datasets were post-processed with TOPODRONE Post Processing software in the field to obtain an accurate x,y,z position of the reservoir bed, taking into account water temperature, salinity and the lever arms of the sensor.

To check and evaluate the accuracy of the data, several cross sections were measured and an accuracy of 5 cm in depth was achieved.

Fig. 2. AQUAMAPPER mission planning in UGCS software.

Fig. 3. Bathymetric data post processing in the TOPODRONE software.

Fig. 4. Bathymetric data together with orthophoto.

The TOPODRONE LIDAR 200+ was then installed on board the same DJI M300 drone and a LIDAR mapping mission was carried out.

Fig. 5. TOPODRONE LIDAR 200+ on board of the DJI M300.

We were proud to see the results of our new LIDAR equipment with an improved high performance GNSS based inertial navigation system, which easily covered 1 sq km with a detailed point cloud of 3 cm x,y,z accuracy from 120 m altitude.

Fig. 6. TOPODRONE LIDAR 200+ point cloud.

Fig. 7. TOPODRONE LIDAR 200+ point cloud.

Several GCPs were measured in the area and all of them showed the outstanding accuracy of TOPODRONE equipment.

Fig. 8. GCPs and LIDAR point cloud locations.

Finally, the TOPODRONE P61 camera was used to acquire RGB and multispectral data to colorise the point cloud and create an orthophoto.

Fig. 9. TOPODRONE P61 with 10-bands AGROWING multispectral lens.

As you can see, in just one day, bathymetric, LIDAR and photogrammetric data were collected and processed together over 1 sq km, showing great efficiency using only one platform (DJI M300) by a team of two people.

Fig. 10. Visualisation of LIDAR and bathymetric data.

Fig. 11. Visualisation of LIDAR and bathymetric data.

Fig. 12. Visualisation of LIDAR and bathymetric data.

"AQUAMAPPER offers a new survey approach that allows us to explore water depths and provide bathymetric data where traditional methods using boats or USVs are prohibited or difficult to use due to ecological reasons or complex terrain. We hope that this equipment will help us to carry out a number of important studies and research projects for coastal and reservoir monitoring," said Gonzalo Malvarez.

"One of the key benefits of the TOPODRONE equipment & technology is the ability to use the same drone hardware for multiple types of studies: photogrammetry, LiDAR, bathymetry. A small team of 1-2 surveyors could carry out large scale aerial surveys without the additional paperwork associated with boat route & fuel consumption permits. The accuracy of data collected by a UAV is comparable to the quality of data collected by traditional boat methods. UAV-based bathymetry can be considered a game changer for reservoir characterisation and modelling, environmental monitoring, studies of sea, lake or river beds," said Federico Alva of Atyges.