3D MODELLING IN TEMPERATE WATERS: BUILDING RIGS AND DATA SCIENCE TO SUPPORT GLASS SPONGE MONITORING EFFORTS IN COASTAL BRITISH COLUMBIA

Abstract. Structure-from-motion (SfM) has emerged as a popular method of characterizing marine benthos in tropical marine environments and could be of tremendous value to glass sponge monitoring and management efforts in the Northeast Pacific Ocean. However, temperate marine environments present a unique set of challenges to SfM workflows, and the combined impact that cold, dark, and turbid waters have on the veracity of SfM derived data must be critically evaluated in order for SfM to become a meaningful tool for ongoing glass sponge research. This paper discusses the design, development, testing, and deployment of an innovative underwater SfM workflow for generating high-resolution 3D models in temperate marine environments. This multi-phase research project (dry-lab, wet-lab, and field), while possibly seen as unconventional, was designed to innovate in two ways. First to build an operational data capture platform to support low-cost SfM-based seafloor surveys. And second, to enable systematic isolation and evaluation of SfM data capture parameters and their implications for representational veracity and data quality. This paper reports the challenges and outcomes from a series of field surveys conducted in Howe Sound, BC, one of which serves as the first of two data sets in a temporal analysis of 3D morphometric change. This research demonstrates that accurate, high-resolution morphometric characterization, of all benthic species and habitats, is dependent on a range of equipment, procedural, and environmental variables. It is also intended to share our applied problem-solving path to successful 3D capture, backed up by robust data science.