Abstract:
Aerial survey of Hound Bay elephant seal colony, Mirounga leonina, during the 2023/24 season conducted using a remotely piloted aerial system (RPAS).
The aerial survey was conducted as part of the Darwin Plus (DPLUS) 214 project: Southwest Atlantic Elephant Seal Population Assessment (SAESPA).
Dataset includes the original images and log files, the original RINEX GNSS (global navigation satellite system) base station files, the post-processed global navigation satellite system and imagery data, along with the resulting georeferenced DSM (digital surface model) and an orthorectified mosaic of the imagery.
This dataset is from flight number DPLUS_214_23 which was carried out on 2024-10-27.
This work was supported by the Overseas Territories Environment and Climate Fund under Grant Darwin Plus ref: DPLUS214: Southwest Atlantic Elephant Seal Population Assessment (SAESPA).
Keywords:
South Georgia, aerial survey, digital surface model, drone, elephant seal, orthorectified mosaic
Fenney, N., Coleman, J., & Bamford, C. (2025). Aerial survey of Hound Bay, South Georgia, elephant seal colony during the 2023/24 season, flight DLPUS_214_23 (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/85de16ff-a3b2-42b4-a898-aea94ee47b83
| Access Constraints: | Data under embargo until 2026-06-31. |
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| Use Constraints: | Data supplied under Open Government Licence v3.0 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. |
| Creation Date: | 2025-01-27 |
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| Dataset Progress: | Planned |
| Dataset Language: | English |
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| Parameters: |
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| Personnel: | |
| Name | UK Polar Data Centre |
| Role(s) | Metadata Author |
| Organisation | British Antarctic Survey |
| Name | Mr Nathan Fenney |
| Role(s) | Investigator, Technical Contact |
| Organisation | British Antarctic Survey |
| Name | Jamie Coleman |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Dr Connor C G Bamford |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Parent Dataset: | N/A |
| Reference: | ||
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| Quality: | Coordinate reference system for outputs: Projection: UTM Zone 23S Horizontal datum: WGS84 Vertical datum: MSL (mean sea level), EGM2008 geoid Resolution of final outputs: DSM (2.1 cm) Orthorectified mosaic (2.1 cm) The camera is placed in the centre of the central component of the drone, with the LiDAR ground sensor immediately below it and offset from the camera. The GNSS antenna is at the front of the drone, offset in the opposite direction. The sampling rate varied throughout the flight, depending on the speed of the platform. Calibration was accounted for in processing. |
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| Lineage/Methodology: | Data collection: Aerial survey conducted using a RPAS (AgEagle eBee X). The survey consisted of collecting overlapping imagery of the target area, with a forward overlap of 80% and a side overlap of 60%. The target altitude during acquisition was 95 m AGL (above ground level). During the aerial surveys a geodetic Trimble GNSS base station receiver collected data. Post flight processing: Precise point positioning (PPP) was undertaken using the online Canadian Spatial Reference System PPP tool to generate the position of the base station during the survey and which was then used to process the eBee X's onboard GNSS receiver using post-processed kinematic (PPK) processing to improve the accuracy of the camera centres captured during flight. Photogrammetry / final outputs: Structure from motion photogrammetry was used to determine the exterior orientation (x, y, z, omega, phi and kappa (or roll, pitch, yaw)) of the camera during image acquisition using a combination of the onboard GNSS solution and common points within the images. Once the camera centre and orientation for each image was determined, a dense point cloud was extracted of the surface within the target area. The dense point cloud was then transformed into a DSM (in metres), which in turn was used to resample the images onto a map projection, removing camera perspective and terrain distortions, in a process called ortho-rectification and resulted in a single complete mosaic of the imagery. |
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| Ownership: | ||
| Temporal Coverage: | |
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| Start Date | 2024-10-27 |
| End Date | 2024-10-27 |
| Spatial Coverage: | |
| Latitude | |
| Southernmost | -54.45722 |
| Northernmost | -54.42987 |
| Longitude | |
| Westernmost | -36.20312 |
| Easternmost | -36.1537 |
| Altitude | |
| Min Altitude | N/A |
| Max Altitude | N/A |
| Depth | |
| Min Depth | N/A |
| Max Depth | N/A |
| Location: | |
| Location | Antarctica |
| Detailed Location | Hound Bay, South Georgia |
| Data Collection: | Data collection equipment: Unmanned aerial vehicle (UAV): Manufacturer: AgEagle Model: eBee X Sensor: AgEagle SODA 3D Flight management software: eMotion (version 3.23.0) GNSS base station: Manufacturer: Trimble Receiver model: R9s Antenna model: Zyphr Model 2 Post-flight processing software: Canadian Spatial Reference System Precise Point Positioning (CSRS-PPP, Version 3) eMotion (version 3.23.0) Photogrammetry software: Pix4D (version 4.9.0.). |
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| Data Storage: | Data is archived using the following structure. Total size: 7.71 GB. DPLUS_214_sortie number (e.g. DLPUS_214_01) 01_flight data: gnss. RINEX files (.YYg, .YYh, .YYn, .YYo,). Each file follows the same naming convention. For example, observation file 10023560.21o refers to the serial number of receiver (1002), day of year (356), session number (0) and file extension (.21o). 01_flight data: imagery. Image files (.jpg). Each file follows the same naming convention. For example, image file IX-12-29034_0069_0001.jpg refers to the platform ID (IX-12-29034 ), the sortie number (0069), the image number (0001) and the file extension (.jpg). 01_flight data: logs. UAV log files (.bb3). Each file follows the same naming convention. For example, log file IX-12-29034_0069_part001.bb3 refers to the platform ID (IX-12-29034 ), the sortie number (0069), the part number (part001) and the file extension (.bb3). These files are binary and can be opened in eMotion, by AgEagle / SenseFly. 02_post_flight_output: csrs_ppp_output. CSRS PPP processing output files (.clk, .csv, .pdf, .pos, .sum, .tro). Each file follows the same naming convention. For example, file 10023560.pdf refers to the serial number of receiver (1002), day of year (356), session number (0) and file extension (.21o). Output files from the Canadian Spatial Reference System Precise Point Positioning service (CSRS-PPP Version 3). 02_post_flight_output: emotion_output/img for the PPK processed image files (.jpg). Each file follows the same naming convention. For example, image file IX-12-29034_0069_0001.jpg refers to the platform ID (IX-12-29034 ), the sortie number (0069), the image number (0001) and the file extension (.jpg). 02_post_flight_output: emotion_output for the PPK processed camera centres (.txt). Each file follows the same naming convention. For example, file IX-12-29034_0069_emotion_geoinfo.txt refers to the platform ID (IX-12-29034 ), the sortie number (0069), program name (emotion), information type (geoinfo) and the file extension (.txt). 03_final_outputs: dsm. Final digital surface model files (.tif, .tfw, .prj). Each file follows the same naming convention. For example, file IX-12-29034_0069_dsm.tif refers to the platform ID (IX-12-29034 ), the sortie number (0069), data type (dsm) and the file extension (.tif). 03_final_outputs: ortho. Final orthorectified moasic files (.tif, .tfw, .prj). Each file follows the same naming convention. For example, file IX-12-29034_0069_transparent_mosaic_group1.tif refers to the platform ID (IX-12-29034), the sortie number (0069), data type (transparent_mosaic_group1) and the file extension (.tif). |
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