Photogrammetry is the process of obtaining detailed information about physical objects and their environment through photography or other imaging techniques to generate an accurate three-dimensional representation.
Watching old Time Team episodes, I admired the skills of the people performing the "geophys", surveying underground features and occasionally modeling the terain and individual finds. Some research revealed it is possible to produce 3-D models of artifacts and even entire sites using free online tools, a camera and a high performance grpahics card in your computer.
I was very surprised to learn how easy it is to create 3D models of just about anything using free, open-source software and a camera of the quality that many people have in their phone. But it does require a pretty good graphics card in your computer. I built my own computer several years ago and the graphics card wasn't up to the job. I'll be getting a new GPU soon, the Asus NVIDIA GeForce GTX 1050.