Introduction

The availability in 2021, on the consumer market of standalone (un-tethered) Head Mounted Displays (HMDs) for Virtual Reality (VR) and Augmented Reality (AR) is an enabling technology in the field of cognitive psychology of the human visual system. It is of special interest in forensic sciences where one need to reconstruct the characteristics of observed phenomena from on a witness testimony.

Such HMDs allow for much easier measurement of some characteristics of the human visual systems. Some issues existing in more basic methods are circumvented, new issues arise.

We already know that some parameters are very often highly mis estimated. This includes the angular height, angular size, These problems are known for over a century ¹⁾, yet, we feel that there is currently a huge lack of characterization of the biaises in the reports.

Some tentative studies were done, but with a lack of control and strict definition of the setup.

As soon as an optical system or a non natural method there is a risk of altering the response in a non detected way.

For instance, alteration by the use of an eye piece alteration by the use of an object held by hand for comparison. alteration by measuring while being sitting or standing.

In addition, these mis estimations are dépendant on the visual context of the observation.

Location of the witness : inside, outside of a building. If looking through a windows. How far away from the window. Dependance of the estimation of the angular size, with the angular height.