Assessing the impact of acute disturbances on the structure and composition of a coral community using innovative 3D reconstruction techniques

Burns, John H. R.; Delparte, Donna; Kapono, L.; Belt, Marjan van den; Gates, Ruth D.; Takabayashi, Misaki

doi:10.1016/j.mio.2016.04.001

Cited by 66 publications

(80 citation statements)

References 43 publications

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“…SfM techniques have been recently used in a range of applications to enhance the field of coral ecology and decipher how changes in reef structural complexity affect ecological processes (Burns et al 2015, Figueira et al 2015, Leon et al 2015, Burns et al 2016, Ferrari et al 2016). This study further supports the use of SfM applications for the field of marine ecology, and shows that highly accurate 3D models can be reconstructed with both Agisoft and Pix4D software packages.…”

Section: Discussionmentioning

confidence: 99%

“…Increases in the frequency and intensity of both global (e.g., climate change, ocean acidification) and local (e.g., pollution, overfishing) stressors has led to significant coral mortality throughout the world's oceans (Harvell et al 1999, Cesar et al 2003, Hoegh-Guldberg et al 2007, Burns et al 2016. Multiple studies have found loss of live coral to cause reductions in reef complexity and detrimental impacts to associated reef fish and invertebrates (Graham et al 2006, Alvarez-Filip et al 2009, Walker et al 2009, Graham and Nash 2013.…”

Section: Introductionmentioning

confidence: 99%

“…Point clouds and digital surface models derived by SfM techniques have been shown to be comparable in terms of data quality and resolution to more expensive LiDAR techniques (Delparte et al 2014, Javernick et al 2014, Remondino et al 2014. Several studies have utilized SfM techniques to create high-resolution 3D reconstructions of coral reef environments to investigate relationships between coral composition and habitat complexity (Burns et al 2015, Figuera et al 2015, Leon et al 2015, Ferrari et al 2016, Burns et al 2016. Characterizing intricate 3D characteristics from coral reef environments can enhance the capability of researchers to investigate and monitor these valuable ecosystems.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Commercial Structure-From-Motion Photogrammety Software Used for Underwater Three-Dimensional Modeling of Coral Reef Environments

Burns

Delparte

2017

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Structural complexity in ecosystems creates an assortment of microhabitat types and has been shown to support greater diversity and abundance of associated organisms. The 3D structure of an environment also directly affects important ecological parameters such as habitat provisioning and light availability and can therefore strongly influence ecosystem function. Coral reefs are architecturally complex 3D habitats, whose structure is intrinsically linked to the ecosystem biodiversity, productivity, and function. The field of coral ecology has, however, been primarily limited to using 2-dimensional (2D) planar survey techniques for studying the physical structure of reefs. This conventional approach fails to capture or quantify the intricate structural complexity of corals that influences habitat facilitation and biodiversity. A 3-dimensional (3D) approach can obtain accurate measurements of architectural complexity, topography, rugosity, volume, and other structural characteristics that affect biodiversity and abundance of reef organisms. Structurefrom-Motion (SfM) photogrammetry is an emerging computer vision technology that provides a simple and cost-effective method for 3D reconstruction of natural environments. SfM has been used in several studies to investigate the relationship between habitat complexity and ecological processes in coral reef ecosystems. This study compared two commercial SfM software packages, Agisoft Photoscan Pro and Pix4Dmapper Pro 3.1, in order to assess the cpaability and spatial accuracy of these programs for conducting 3D modeling of coral reef habitats at three spatial scales.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison of Commercial Structure-From-Motion Photogrammety Software Used for Underwater Three-Dimensional Modeling of Coral Reef Environments

Burns

Delparte

2017

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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“…Previous studies have used structure from motion techniques to obtain measurement data from coral reefs [12,36,37], and while some studies have quantified measurement error in relation to 'true volume/surface area' as determined by laser scanning or traditional methods [10,13], no attempt to verify whether the measurements obtained using structure from motion were reproducible until now. Volume and surface area are basic measurements, and the implications of this study should also apply to studies that assess rugosity or other structural characteristics using this technique [9,11,50].…”

Section: Discussionmentioning

confidence: 99%

“…Once models are completed, they can be used to compare physical aspects of coral such as volume, proportion of surface area of living and/or dead coral, similarly to Burns et al [50] or Ferrari et al [9], while recognizing that changes that are lower than 15% for volumetric measurements and 12% for surface area measurements are likely due to structure from motion measurement errors and may not be indicative of true variation in the measurement.…”

Section: Discussionmentioning

confidence: 99%

How Reliable Is Structure from Motion (SfM) over Time and between Observers? A Case Study Using Coral Reef Bommies

et al. 2017

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Recent efforts to monitor the health of coral reefs have highlighted the benefits of using structure from motion-based assessments, and despite increasing use of this technique in ecology and geomorphology, no study has attempted to quantify the precision of this technique over time and across different observers. This study determined whether 3D models of an ecologically relevant reef structure, the coral bommie, could be constructed using structure from motion and be reliably used to measure bommie volume and surface area between different observers and over time. We also determined whether the number of images used to construct a model had an impact on the final measurements. Three dimensional models were constructed of over twenty coral bommies from Heron Island, a coral cay at the southern end of the Great Barrier Reef. This study did not detect any significant observer effect, and there were no significant differences in measurements over four sampling days. The mean measurement error across all bommies and between observers was 15 ± 2% for volume measurements and 12 ± 1% for surface area measurements. There was no relationship between the number of pictures taken for a reconstruction and the measurements from that model, however, more photographs were necessary to be able to reconstruct complete coral bommies larger than 1 m 3 . These results suggest that structure from motion is a viable tool for ongoing monitoring of ecologically-significant coral reefs, especially to establish effects of disturbances, provided the measurement error is considered.

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A simple, fast, and repeatable survey method for underwater visual 3D benthic mapping and monitoring

Pizarro

Friedman²,

Bryson

et al. 2017

Ecology and Evolution

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Visual 3D reconstruction techniques provide rich ecological and habitat structural information from underwater imagery. However, an unaided swimmer or diver struggles to navigate precisely over larger extents with consistent image overlap needed for visual reconstruction. While underwater robots have demonstrated systematic coverage of areas much larger than the footprint of a single image, access to suitable robotic systems is limited and requires specialized operators. Furthermore, robots are poor at navigating hydrodynamic habitats such as shallow coral reefs. We present a simple approach that constrains the motion of a swimmer using a line unwinding from a fixed central drum. The resulting motion is the involute of a circle, a spiral‐like path with constant spacing between revolutions. We test this survey method at a broad range of habitats and hydrodynamic conditions encircling Lizard Island in the Great Barrier Reef, Australia. The approach generates fast, structured, repeatable, and large‐extent surveys (~110 m2 in 15 min) that can be performed with two people and are superior to the commonly used “mow the lawn” method. The amount of image overlap is a design parameter, allowing for surveys that can then be reliably used in an automated processing pipeline to generate 3D reconstructions, orthographically projected mosaics, and structural complexity indices. The individual images or full mosaics can also be labeled for benthic diversity and cover estimates. The survey method we present can serve as a standard approach to repeatedly collecting underwater imagery for high‐resolution 2D mosaics and 3D reconstructions covering spatial extents much larger than a single image footprint without requiring sophisticated robotic systems or lengthy deployment of visual guides. As such, it opens up cost‐effective novel observations to inform studies relating habitat structure to ecological processes and biodiversity at scales and spatial resolutions not readily available previously.

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Assessing the impact of acute disturbances on the structure and composition of a coral community using innovative 3D reconstruction techniques

Cited by 66 publications

References 43 publications

Comparison of Commercial Structure-From-Motion Photogrammety Software Used for Underwater Three-Dimensional Modeling of Coral Reef Environments

Comparison of Commercial Structure-From-Motion Photogrammety Software Used for Underwater Three-Dimensional Modeling of Coral Reef Environments

How Reliable Is Structure from Motion (SfM) over Time and between Observers? A Case Study Using Coral Reef Bommies

A simple, fast, and repeatable survey method for underwater visual 3D benthic mapping and monitoring

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