Figure 2
From: Dye tracing and concentration mapping in coastal waters using unmanned aerial vehicles
Object-based image classification steps. Orthomosaic of the unmanned aerial vehicle flight survey between 13:37 and 13:53 (a) and classification steps of dye plume extent mapped using multi-threshold segmentation (b), thresholding of the Red:Blue and Red:Green band ratios (c) and the Red:Green band ratio and (Red/Blue) × (Red/Green) interaction term (d), gap-filling of unclassified objects enclosed by mapped dye extent (e), and smoothing of the object edges (f). Software used to produce the maps: Agisoft Metashape version 1.7.1 (www.agisoft.com), eCognition Developer version 10.1.1 (https://geospatial.trimble.com/products-and-solutions/ecognition) and ArcGIS version 10.5.1 (www.esri.com/en-us/arcgis).
