The video below demonstrates the importance of light for identifying potential archaeological features. Flat light or overcast conditions, which limit shadows, make it extremely difficult to differentiate the small topographical changes that may be indicative of archaeological features.
In the video below a drone / UAV survey was undertaken to create a detailed 3D model or Digital Surface Model (DSM). The DSM, as a software construct of the 3D surface of the ground, can have its texture changed and can be lit from any angle providing the shadows that may otherwise be lacking.