Cost and time-effective method for multi-scale measures of rugosity, fractal dimension, and vector dispersion from coral reef 3D models

• DOI: 10.1371/journal.pone.0175341
• Publication Date: 2017-04-13T14:03:21Z
• Authors: G. C. Young; S. Dey; A. D. Rogers; D. Exton
• Keywords: Rugosity

We present a method to construct and analyse 3D models of underwater scenes using single cost-effective camera on standard laptop with (a) free or low-cost software, (b) no computer programming ability, (c) minimal man hours for both filming analysis. This study focuses four key structural complexity metrics: point-to-point distances, linear rugosity (R), fractal dimension (D), vector dispersion (1/k). the first assessment accuracy precision structure-from-motion (SfM) from an uncalibrated GoPro™ at small scale (4 m2) show that they can provide meaningful, ecologically relevant results. Models had root mean square errors 1.48 cm in X-Y 1.35 Z, accuracies 86.8% 99.6% (D scales 30–60 cm), 93.6% 1–5 86.9 Values R were compared in-situ chain-and-tape measurements, while values D 1/k ground truths printed objects modelled underwater. All metrics varied less than 3% between independently rendered models. thereby improve rigorously validate tool ecologists non-invasively quantify coral reef variety multi-scale metrics.