Basic Photogrammetry for Crime and Crash Scenes
Basic Photogrammetry for Crime and Crash Scenes
by George M. Bonnett, JD
Frustrated that the cost of photogrammetry software and the necessary training far exceeds
the limits on your budget? One of IPTM’s latest articles, Basic Photogrammetry for Crime and Crash Scenes,
written by George Bonnett, will show you the basics of two-dimensional photogrammetry.
Photogrammetry, or numerical rectification, is used to “map” various points on a single plane
to the desired coordinate system. Numerical rectification is simpler than other techniques and the
software required is usually much less expensive and easier to use. When dealing with crime or
crash scenes, the desired coordinate system is usually a scale diagram and numerical rectification
is ideally suited for this purpose.
You will see that while a two-dimensional plane is a prerequisite, this plane need not be
a horizontal surface and there is no requirement that the entire photograph be of a single planar
surface. In fact, the basic requirements for two-dimensional photogrammetry are a single
photograph and a scale diagram of a two-dimensional surface within the photograph that contains
the object that is the focus of the process. Numerical rectification requires that four control
or calibration points be located on the plane that can be matched to four corresponding points on
the scale diagram.
Mr. Bonnett takes you step-by-step through three different exercises that will teach you
the basics of using photogrammetry to obtain measurements from photographic images using numerical
rectification. Since the topics of creating a scale diagram and forensic mapping are outside the
scope of this article, the author assumes you have previous experience in these areas.
George Bonnett is a combat proven Marine Corps aviator turned police officer turned attorney
turned crash reconstructionist turned software developer and author (REC-TEC). His whole life
has depended on minute attention to detail. In this book, he gives you the benefit of his years
of experience.
Specifications: 38 pages; 8½”x11; saddle stitched; Publisher: IPTM (September 2005)
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