Event Title

Benefits and challenges of UAV imagery for eelgrass (Zostera marina) mapping in small estuaries of the Salish Sea

Presentation Abstract

Seagrasses are a fundamental component of nearshore marine habitats and as such, concerted effort has been put into developing remote sensing methods for mapping and monitoring these important habitats. However, in the small coastal bays of the Salish Sea, traditional aerial or satellite remote sensing can be cost-prohibitive or lack sufficient spatial resolution to detect the small, fringing, and often patchy eelgrass (Zostera marina) meadows. Bridging the gap between remotely sensed data and ground-based mapping techniques, aerial imagery collected by Unmanned Aerial Vehicle (UAV) is revolutionizing the study of fine-scale ecological phenomena. This paper presents a method for collection and processing of UAV imagery to map eelgrass (Zostera marina) at three small coastal estuaries in the Salish Sea of British Columbia. A quad-copter style XAircraft X650 UAV equipped with a rectilinear GoPro Hero 3+ was used to acquire images with a ground resolution of 2 cm. Pix4D Pro software was used to orthorectify, georeference, and mosaic UAV imagery into continuous orthomosaics. To delineate eelgrass, a manual classification approach of segmented image objects was used on an eelgrass presence or absence basis using ground reference data collected in the form of underwater videography collected by kayak. Mapping accuracies of 95.3%, 88.9%, and 90.1% were achieved for Village Bay, Horton Bay, and Lyall Harbour respectively. The benefits (flexible acquisition, high resolution) and challenges (inconsistent radiometry, small footprint) of UAV mapping of seagrasses are compared to the use of conventional remote sensing technologies.

Session Title

Posters: Data & Information Management

Conference Track

SSE18: Posters

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE18-35

Start Date

5-4-2018 11:30 AM

End Date

5-4-2018 1:30 PM

Type of Presentation

Poster

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 5th, 11:30 AM Apr 5th, 1:30 PM

Benefits and challenges of UAV imagery for eelgrass (Zostera marina) mapping in small estuaries of the Salish Sea

Seagrasses are a fundamental component of nearshore marine habitats and as such, concerted effort has been put into developing remote sensing methods for mapping and monitoring these important habitats. However, in the small coastal bays of the Salish Sea, traditional aerial or satellite remote sensing can be cost-prohibitive or lack sufficient spatial resolution to detect the small, fringing, and often patchy eelgrass (Zostera marina) meadows. Bridging the gap between remotely sensed data and ground-based mapping techniques, aerial imagery collected by Unmanned Aerial Vehicle (UAV) is revolutionizing the study of fine-scale ecological phenomena. This paper presents a method for collection and processing of UAV imagery to map eelgrass (Zostera marina) at three small coastal estuaries in the Salish Sea of British Columbia. A quad-copter style XAircraft X650 UAV equipped with a rectilinear GoPro Hero 3+ was used to acquire images with a ground resolution of 2 cm. Pix4D Pro software was used to orthorectify, georeference, and mosaic UAV imagery into continuous orthomosaics. To delineate eelgrass, a manual classification approach of segmented image objects was used on an eelgrass presence or absence basis using ground reference data collected in the form of underwater videography collected by kayak. Mapping accuracies of 95.3%, 88.9%, and 90.1% were achieved for Village Bay, Horton Bay, and Lyall Harbour respectively. The benefits (flexible acquisition, high resolution) and challenges (inconsistent radiometry, small footprint) of UAV mapping of seagrasses are compared to the use of conventional remote sensing technologies.