The technology for developing topographic maps is not necessarily cutting edge. According to USGS, the first map issued in the United States in which the relief is shown by contours was in Maryland, in 1835.
20th Century aviation and advanced mapping instrumentation made cartography more accessible to Engineers. However, equipment and manpower continue to be costly and less accurate.
Fast forward to present day, Unmanned Services works with the construction industry to create hi-resolution maps and geo-tiff images. These images can easily be uploaded into standard engineering design software. Architects and Engineers can create 3D models for overlays; easily identify contours for retaining walls and structural design.
How is this done? Similar to general aviation, except more precise since the instrumentation is now flying lower to the ground. This is the same concept as zooming in with a camera, higher resolution produces improved accuracy. Unmanned Services uses precision geo-triangulation and a small manpower footprint to create maps that are between 2-7 centimeters accurate. The USGS engineering and architectural design standard is one meter.