Visto gracias a Schneier
https://www.schneier.com/blog/archives/2019/09/new_biometrics.html
New surveillance tech means you'll never be anonymous again | WIRED UK
https://www.wired.co.uk/article/surveillance-technology-biometrics
"Bum detection
Then there are the identification techniques designed for very specific use cases. One pioneering suggestion from a team of Japanese researchers for an anti-theft system for cars was based on using 360 sensors to measure the unique shape of the driver's rear end. Despite achieving a 98 per cent accuracy rate in trials."