Note that before lidar, photographs taken from a plane were also very useful for discovering archeological sites that are not obvious while seen from the ground

Note that before lidar, photographs taken from a plane were also very useful for discovering archeological sites that are not obvious while seen from the ground. Wikipedia has a whole article on it, including lidar developments: https://en.wikipedia.org/wiki/Aerial_archaeology https://en.wikipedia.org/wiki/Aerial_archaeology