Accuracy Assessment of Thematic maps of Hawaiʻi Coral Reef Habitats Based on Image Interpretation from Three Different types of Remotely Sensed Data

Abstract

This study quantifies and compares the accuracy of thematic habitat maps created from three types of remotely sensed data for Hawaiian near-shore coral reef environments. Remotely sensed data of similar spatial and temporal resolution were collected at four test areas chosen to represent a cross section of the coral reef habitat types present in the main Hawaiian Islands. Imagery derived from aerial photography, airborne AURORA hyperspectral data, and satellite IKONOS multispectral data was used to make maps by manual photointerpretation via "head's up" computer digitizing. Thematic map classes were based on a NOAA peer-reviewed hierarchical coral reef habitat classification scheme with four first-level major classes (unconsolidated sediments, submerged aquatic vegetation, coral reef and hard bottom, other delineations) and 28 detailed classes. For accuracy assessment, ground truth data were collected at 1225 stations selected by a stratified random sampling design. Each of the four test areas was sampled and tested independently, and the data were combined for a region-wide analysis. Accuracy assessment tests included error matrix analyses (overall, user's and producer's accuracy), the kappa statistic, the tau coefficient, and tests for significance differences between tau coefficients for maps generated from the three different types of imagery. The statistical accuracy assessment tests were preformed at the first level of the classification scheme. There were no significant differences between tau coefficients for maps generated from any of the three types of remotely sensed imagery at two of the four test areas (