A camera-based security system protects an asset by detecting an aerial surveillor and consequently storing notifications into a video archive, alerting to an operator console, and actuating privation apparatus. One or more cameras provides video streams to a processor which derives object motion. Attributes of object motion trigger notification to record and alert on conditions associated with an aerial surveillor. Tracking of pixels, pixel blocks, and motion vectors enable rules based determination of an airborne surveillance vehicle according to characteristic hovering or lingering by masking LSB of accumulated positive and negative movements. Actuators cause privation enhancement apparatus to obfuscate the protected asset (structure, area, or volume) or to interpose between the protected asset and the surveillor. The method traces a travel path of an object; and determines a ray from a private property to a surveillor drone.