2.7 Photogrammetry

2.7 Photogrammetry

We have briefly mentioned photogrammetry and several of you have found related examples in the previous week. Amazing things are happening in the area of photogrammetry! Photogrammetry, for those who are not familiar with it, can be loosely defined as the art and science of measuring in photos. For the case of 3D modeling this has vast applications:

• Imagine that a house you would like to model no longer exists in the real world but you still have access to images through, for example, a library. Penn State and its main campus have undergone drastic changes in the last 170 years. Naturally, not all buildings that were on campus are still there. Penn State’s library has taken on the task to preserve some of the knowledge we have about previous states of the campus and has created digital archives for images but also maps. Here is an example: Maps: State College Change Through Time.
• Imagine that you are an archeologist and that you are interested in preserving the heritage of an ancient site. There are high-level approaches through companies like Bentley, who recently modeled the Penn State Campus but they are really expensive and may or may not be necessary for your purposes. A substantially less expensive approach that nonetheless provides you with a 3D model of a site can be accomplished with so-called structure from motion mapping. Below is an example from a project of the University of Ghent in Belgium and Penn State's Obelisk that a ChoroPhronesis member (Jiayan Zhao) created.

Example: The Mayan site of Edzna in Campeche (Mexico)

Example: Penn State's Obelisk

Photogrammetry has traditionally been within the field of geodesy and remote sensing, but its applications are becoming ubiquitous. Originally, it was used to measure distances, define the extent of areas, and essentially identify and geo-locate terrain features with the purpose to complement databases and/or to create maps.