Forensic Video Services - Forensic Imagery Analysis, Facial Mapping, Body Mapping, Photogrammetry
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Photogrammetry
Forensic Video Services
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Photogrammetry  Photogrammetry is the process of taking precise measurements using imagery.  Using this technique FVS can accurately  compare a person or object in CCTV footage against an object of known height.  How this is achieved  The following video gives a brief explanation of how a photogrammetry exercise is conducted:  Photogrammetry measurement  The known-scale technique has been developed from scaling and measuring methods taught by the  Joint School of Photographic Interpretation (JSPI). Using a known scale, in this case a full-size scale  bar of the type shown (right), the subject’s height is compared with that of the scale bar in a  reconstruction. The known scale technique is very accurate and is a tried and tested method; currently in use by  photogrammetrists in the Armed Forces and other leading UK forensic imagery companies.  How accurate is it?  It stands to reason that height can vary depending on where a person is in their stride and stance. To  counteract this we select images where a person is standing on a straight leg and displaying their full  height. It is also accepted that a person standing ‘bolt upright’ is unatural and does not represent their  height when standing in relaxed position.  It is an accepted part of the methodology that photogrammetrists (as with many scientific disciplines)  quote a tolerance or ‘margin of error’ in their work. FVS offer a tolerance of +/- 1.5%, which typically  provides a range of +/- 1” (one inch).  In practice, this means that a measurement of 5’ 6” +/- 1” means that if a suspect is  between 5’5” - 5’7” they would be a possible contender on height and therefore cannot be eliminated. 
Forensic Scale Bar 2014 Photogrammetry
Case Study - Photogrammetry in practice A robbery (which was captured on CCTV) took place in a fast food outlet in Birmingham.  Clothing, jewellery and shoes were recovered from a suspect. FVS undertook a measuring and footwear reconstruction exercise on behalf of West Midlands Police. The recovered shoes and the clothing were shown to be the same type and style as the items worn by the offender. The offender’s height was shown to be consistent with that of the suspect. The graphic shows the offender’s height which aligns with the measuring pole at 5’ 9” +/- 1.5%.
FVS have the capability to produce accurate measurements of persons or objects,  from CCTV imagery alone through use of photogrammetry techniques.
Forensic Video Services - Imagery and Audio Analysis for use in Court