Photogrammetry is the science of making geometric measurements from photographs. "Photogram" is a photo and "Metry" is geometry. Since a photographer taking a picture of the world of 3D and projects it on a flat 2D image plane, we lose depth information.
However, with best photogrammetry software, experts do the opposite. By knowing some information about the camera that takes photographs and by having two or more images of the same object from different perspectives, we can get some 3D information back.
There are different approaches for photogrammetric analysis based on the number and quality photos. Each approach has advantages in accuracy and simplicity as well as what it really can be output for visual presentation.
In a scene is well documented that photogrammetry has been taken into account. All the details can be created in 3D and the accuracy of the measurement can be simply stated as limited by the size of the photos taken and by how well the objects appear in the photo.
What most people who are responsible for taking photos in an accident or crime scene do not know, is that they can capture the entire data set of 3D measurement by simply adjusting their techniques to make their photos "photogrammetry friendly".
In most cases, the methods required for data capture only a matter of a few extra minutes and some additional photos at the highest resolution possible.
Photogrammetry can bring great value to lawyers and accident reconstructionists who need the benefits of "better information" in a court case or an accident reconstruction report.
Having accurate data that may not be considered against the board or simply discarded as impossible to obtain can often be the difference in winning or losing the case or settlement.