Using Digital Photographs To Extract Evidence
Once all available data has been collected by accident scene investigators and law enforcement officers, camera matching, photogrammetry or rectification can be used to determine the exact location of physical evidence shown in the accident scene photos.
- Camera matching: Camera matching uses accident scene photos that show various points of evidence. The technique uses CAD software to create a 3-dimensional model of the accident site and roadway surface. All survey data and photos are then imported into a three dimensional software package like 3D Studio Max. A virtual camera can be then be positioned relative to the 3D roadway surface. Physical evidence is then mapped from the photos onto the 3D roadway to create a three dimensional accident scene drawing.
- Photogrammetry: Photogrammetry is used to determine the three-dimensional geometry of an object on the accident scene from the original two dimensional photos. The photographs can be used to extract evidence that may be lost after the accident is cleared. Photographs from several viewpoints are imported into software like PhotoModeler. The forensic engineer can then choose points common to each photo. The software will calculate the location of each point in a three dimensional coordinate system.
- Rectification: Photographic rectification is also used to analyze evidence that may not have been measured at the accident scene. Two dimensional rectification transforms a single photograph into a top-down view. Software like PC-Rect can be used to rectify a digital photograph.
Read more about this topic: Accident Analysis
Famous quotes containing the words photographs, extract and/or evidence:
“All photographs are there to remind us of what we forget. In this—as in other ways—they are the opposite of paintings. Paintings record what the painter remembers. Because each one of us forgets different things, a photo more than a painting may change its meaning according to who is looking at it.”
—John Berger (b. 1926)
“The past is interesting not only for the beauty which the artists for whom it was the present were able to extract from it, but also as past, for its historical value. The same goes for the present. The pleasure which we derive from the representation of the present is due not only to the beauty in which it may be clothed, but also from its essential quality of being present.”
—Charles Baudelaire (1821–1867)
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—Herbert, Sir Beerbohm (1853–1917)