The Mermaid Underwater Dataset (SR202204_LDM-S) is a set of underwater images acquired at approximately 20 m depth at the La Sirène site (Lion-de-Mer) in Saint-Raphaël (France) during the Submeeting 2022, an underwater robotic workshop (https://submeeting2022.univ-tln.fr/). A micro geodesic network was established at the acquisition site to serve as ground truth.

The covered area is approximately 150 m2, with a sub-millimeter GSD. It is composed of a statue of a mermaid, a sandy plain with stones and a rocky area. Sealife is distributed across these different spaces. Data is acquired from a single camera by divers with natural lighting and is provided without pre-processing.

This dataset can, among other things, be used in the context of work on underwater 3D reconstruction or on underwater visual navigation.

The dataset is composed of the following data:
- A PDF file bringing together information relating to the micro geodesic network (acquisition methods, data processing method, GCPS, measurements and diagram) [SR202204_LDM-S_D00_GroundTruth_report.pdf]
- An STL file representing the micro geodesic network on a relative scale [SR202204_LDM-S_D00_GroundTruth_network.stl]
- A folder containing all the images [SR202204_LDM-S_D01]
 - A PDF file bringing together information relating to the image data (acquisition method, data format, sensor information including calibration value, overview of the area under different views with mosaic, 3D clouds and textured mesh created from the images, overview of the trajectory) [SR202204_LDM-S_D01_readme.pdf]
- An XML file which brings together information relating to the pose of each image estimated from a multi-view bundle adjustment [SR202204_LDM-S_C01_camera_poses]