What is the simulation method of surveying and mapping real estate? Was it measured by aerial photography?

The average error of ground feature points on the real estate frame plan measured by simulation method on the map is less than 0.5 mm When using the existing cadastral map and topographic map to compile the real estate framing map, the average error of the ground feature points on the map is less than 0.6 mm. When using the existing coordinates or existing maps to develop the real estate framing map, the display error on the map is less than 0. 1.