Simple methods for interactive 3D modeling, measurements, and digital databases of coral skeletons

Coral studies rely on comparative research between several reference coral skeletons and living organisms imaged on reefs. However, many of these skeletons are part of collections, making extensive comparative works difficult. Nowadays, imaging technologies and image processing approaches allow acquisition of three-dimensional (3D) datasets that can be converted to virtual models. These models can be made easily accessible and shared among collaborators or researchers using the Internet. Here, we compare high cost and low cost technologies on coral skeletons as well as imaging phantoms for accurate reference. We generated 3D models that were compared. Even though CT scanning and photogrammetry are the most accurate methods the latter is far less costly. It also allows for texture mapping, an essential tool in the field, and easy dataset handling. We submitted these 3D virtual models to experts for taxonomical identification, and they identified all specimens accurately. Finally, we further discuss applicability of our approach on museum collections, living corals, and field work.