Overview of ImageCLEFcoral 2021 - Coral Reef Image Annotation of a 3D Environment.

This paper presents an overview of the ImageCLEFcoral 2021 task that was organised as part of the Conference and Labs of the Evaluation Forum CLEF Labs 2021. The task addresses the problem of automatically segmenting and labelling a collection of underwater images that can be used in combination to create 3D models for the monitoring of coral reefs. The training dataset contained 882 images from 6 subsets from 4 locations. 1 subset was complete (containing all the images to build the 3D model) and 5 subsets containing a partial collection. The test data (491 images) contained the images required to complete 4 of the partial image sets from each of the 4 locations (the final partial subset is not used for testing, only training). 8 teams registered to the ImageCLEFcoral task, of which 3 teams submitted 8 runs. Participants’ entries showed that although automatic annotation of benthic substrates was possible, developing a generic algorithm to work across multiple geographical locations will be difficult due to the variation of characteristics within and between classification types.