Application of Geobia to map the seafloor

Abstract

ABSTRACT:Geographic Object-Based Image Analysis (GEOBIA) has been successfully employed to map terrestrial environments. However, 71% of Earth's surface is covered by seawater and standard optical methods suitable for mapping the land surface have limited application in such environments. Application of GEOBIA to marine environments has nevertheless been attempted and can generally be subdivided into three domains: 1. The intertidal zone and shallow subtidal zone have been mapped with optical data and application of GEOBIA in such environments can be seen as a seaward extension of terrestrial approaches. 2. Photographs of the seafloor give very detailed but spatially limited information. GEOBIA methods have been applied to classify benthic species and habitats and estimate seafloor complexity among others. 3. Due to the rapid attenuation of light in water, the method of choice to map the seafloor employs sound. Modern multi-beam echosounders map the seafloor in high detail. Such sensors measure the topography (water depth) and the strength of the returning signal (backscatter), which can be used to characterise the seafloor substrates and habitats. This contribution will focus on the application of GEOBIA to marine acoustic datasets. A generic workflow for object-based acoustic seafloor mapping will be showcased and the current state of the application of GEOBIA to marine acoustic data will be discussed.

Rapid Assessment of Seabed Habitats Around Pitcairn Island in Aid of Activity Management During the COVID-19 Global Pandemic

“…Conditional inference trees are a non-parametric class of decision tree and use recursive partitioning of dependent variables based on the values of correlation (Hothorn et al, 2006). The output from a conditional inference tree is relatively simple to understand and allows the user to easily translate the splits into a rule set for classification (Diesing, 2016). As the number of video transects was fairly low within this study there is a chance the splits that the model has created may not truly reflect the whole study area.…”

Bathymetric Survey of the St. Anthony Channel (Croatia) Using Multibeam Echosounders (MBES)—A New Methodological Semi-Automatic Approach of Point Cloud Post-Processing

“…MBES are now advanced to a level where the ultra-high-resolution (cm) of underwater floor mapping [9] is performed at a similar spatial resolution as the remote sensing of the terrestrial environment [10]. MBES systems can typically collect high-resolution bathymetry (the travel time of the sound), water column [11], and backscatter (the intensity of the returned signal) data simultaneously [1,[12][13][14]. Therefore, the MBES systems have a wide range of applications, which include: the acquisition of bathymetric data [15][16][17]; hydrographic charting [4,7,18]; habitat mapping [4,9,12,[18][19][20]; the analysis of the benthic fauna [21]; the production of thematic maps [22]; tidal channels modeling [23]; geomorphometric analysis [2,[24][25][26]; seafloor facies classification [4,27,28]; habitat suitability modeling [29,30]; the mapping of underwater archaeological sites [31][32][33][34][35][36]; morphological and sedimentological evolution [7,37]; the mapping of seafloor substrates [38]; geohazard assessments [39]; analyzing the challenges associated with climate change…”