Car speed estimation based on image scale factor

Luciano R Costa; Michelle S Rauen; Andressa B Fronza

doi:10.1016/j.forsciint.2020.110229

Car speed estimation based on image scale factor

Forensic Sci Int. 2020 May:310:110229. doi: 10.1016/j.forsciint.2020.110229. Epub 2020 Feb 29.

Authors

Luciano R Costa¹, Michelle S Rauen², Andressa B Fronza³

Affiliations

¹ Instituto Geral de Perícias de Santa Catarina, Rua Pastor William Richard Schisler Filho, 590 - Bairro Itacorubi, Florianópolis, SC, Brazil(1). Electronic address: lucianorc@igp.sc.gov.br.
² Instituto Geral de Perícias de Santa Catarina, Rua Pastor William Richard Schisler Filho, 590 - Bairro Itacorubi, Florianópolis, SC, Brazil(1). Electronic address: michellerauen@igp.sc.gov.br.
³ Instituto Geral de Perícias de Santa Catarina, Rua Pastor William Richard Schisler Filho, 590 - Bairro Itacorubi, Florianópolis, SC, Brazil(1). Electronic address: andressafronza@igp.sc.gov.br.

PMID: 32172177
DOI: 10.1016/j.forsciint.2020.110229

Abstract

Speed estimation by video analysis has been an increasingly common method for obtaining the speed of vehicles involved in traffic accidents. Generally, the estimate is based on reference measurements obtained on site or on measurements calculated by photogrammetric techniques. In this work, we proposed an alternative method for estimating the speed of a vehicle with longitudinal trajectory relative to the camera, either approaching it or moving away from it. The method uses the "image scale factor in pixels" to calculate the distance from the vehicle to the camera in different video frames, thus allowing the estimation of a vehicle's average speed. The results were verified by means of a simulation, with a vehicle moving at known speeds. The small deviation obtained supports the forensic use of the method in speed estimation by video analysis.

Keywords: Forensic science; Photogrammetry; Vehicle speed; Video analysis.