Object-based post-fire aerial image classification for building damage, destruction and defensive actions at the 2012 Colorado Waldo Canyon Fire

Abstract

We compare the use of post-fire aerial imagery to ground-based assessment for identifying building destruction and damage at the 2012 Colorado Waldo Canyon Fire. We also compare active-fire defensive actions identified via manual and automated post-fire image classification to defensive actions documented from ground-based assessments (witness discussions, vehicle logs and images). For building destruction, manual and automatic image classification compared favourably to ground-based assessment, with low errors of commission (0.0–0.4%) and omission (0–1.2%). For building damage, classifying imagery manually had significant errors of commission and omission (59.0% and 57.9%) because ground-based assessments missed roof damage and image classification excluded interior and side damage, indicating the need for both techniques. Classifying imagery automatically for indicators of active-fire water suppression on buildings has Kappa statistics indicating a substantial agreement with documented water suppression. Manual and automatic image classification underestimated the full extent of documented defensive actions but showed a statistically significant dependence between fire cessation and defensive actions. These results show post-fire imagery to be a useful addition to other techniques for identifying building damage, destruction and defensive actions. Also demonstrated is the importance of accounting for defensive actions and other factors in wildland–urban interface fire studies.