US Patent 11428527 Monitoring method, monitoring system, and program

Disclosed is a monitoring method wherein: a target is prepared using terrain model data including terrain location information; at a first time, an image of the target is picked up by means of an image pickup unit of a surveying device, and first image data is generated; at a second time after the first time, an image of the target is picked by means of the image pickup unit of the surveying device, and second image data is generated; and displacement of the target is detected using a first image based on the first image data, and a second image based on the second image data.