  Herein, we present CoDA, the Coral Dendroid structure Analyzer, a visual
analytics suite that allows for the first time to investigate the ontogenetic
morphological development of complex dendroid coral colonies, exemplified on
three important framework-forming dendroid cold-water corals: Lophelia pertusa
(Linnaeus, 1758), Madrepora oculata (Linnaeus, 1758), and Goniocorella dumosa
(Alcock, 1902). Input to CoDA is an initial instance segmentation of the coral
polyp cavities (calices), from which it estimates the skeleton tree of the
colony and extracts classical morphological measurements and advanced shape
features of the individual corallites. CoDA also works as a proofreading and
error correction tool by helping to identify wrong parts in the skeleton tree
and providing tools to quickly correct these errors. The final skeleton tree
enables the derivation of additional information about the calices/corallite
instances that otherwise could not be obtained, including their ontogenetic
generation and branching patterns - the basis of a fully quantitative
statistical analysis of the coral colony morphology. Part of CoDA is CoDAGraph,
a feature-rich link-and-brush user interface for visualizing the extracted
features and 2D graph layouts of the skeleton tree, enabling the real-time
exploration of complex coral colonies and their building blocks, the individual
corallites and branches.
  In the future, we expect CoDA to greatly facilitate the analysis of large
stony corals of different species and morphotypes, as well as other dendroid
structures, enabling new insights into the influence of genetic and
environmental factors on their ontogenetic morphological development.
