  Indoor exploration is an important task in disaster relief, emergency
response scenarios, and Search And Rescue (SAR) missions. Unmanned Aerial
Vehicle (UAV) systems can aid first responders by maneuvering autonomously in
areas inside buildings dangerous for humans to traverse, exploring the
interior, and providing an accurate and reliable indoor map before the
emergency response team takes action. Due to the challenging conditions in such
scenarios and the inherent battery limitations and time constraints, we
investigate 2D autonomous exploration strategies (e.g., based on 2D LiDAR) for
mapping 3D indoor environments. First, we introduce a battery consumption model
to consider the battery life aspect for the first time as a critical factor for
evaluating the flight endurance of exploration strategies. Second, we perform
extensive simulation experiments in diverse indoor environments using various
state-of-the-art 2D LiDAR-based exploration strategies. We evaluate our
findings in terms of various quantitative and qualitative performance
indicators, suggesting that these strategies behave differently depending on
the complexity of the environment and initial conditions, e.g., the entry
point.
