1. Photogrammetry enables measurements to be derived from photographs. But why use photos?

• Scenes and objects might be too complex, or inaccessible, or both for measurement by other means.
• Photography is a very quick recording method for later data analysis: important if there is insufficient time for measurement by other means.
• Photographic records (e.g. from 35mm, digital or video cameras) may be the only source of information available.
• Enables measurement extraction and image analysis for an indefinite period after the initial recording.
• Preserves a record of orginal conditions after changes have occurred.
• Photographic recording avoid or minimises the risk of contamination of the scene: important for evidentiary applications.

2. Photogrammetry enables "real-world" rotatable 3D computer imaging. But what is the advantage of this?

• Compared with computer generated rotatable 3D renderings, complex scenes or objects can be modeled much more quickly.
• The preservation of the original photographic record in the model may have greater credibility and may be valuable for evidentiary applications.

Forensic investigations
Crime scenes; accidents; structural failures; effects of natural disasters.