1. An unmanned aerial vehicle (UAV) assessment system for capturing orthogonal images of sample regions of having a target square footage, comprising: a camera to capture images of at least a portion of a roof of a structure; a pitch determination system to determine a pitch of a surface of the roof that is at an angle relative to a downward direction; and an imaging system to: adjust a tilt angle of the camera of the UAV to a non-zero angle relative to the downward direction to align an optical axis of the camera substantially perpendicular to the surface of the roof of the structure, and capture an image of a portion of the roof of the structure at a distance and field of view that corresponds to a sample region of the surface of the roof having a target square footage with the optical axis of the camera aligned perpendicular to the surface of the roof by adjusting the tilt angle of the camera of the UAV, based on the determined pitch of the surface of the roof.