Influence of transfer function on luminance distribution in head-mounted displays: a museum case study

Virtual reality has proven its potential in many applications, generating a great deal of interest in lighting design within the scientific community as well. Flexible and economical investigation tools, such as virtual reality, can help examine different light settings and assist in determining the optimal ones from a human perspective. Nevertheless, the management of the input stimuli remains a crucial aspect to investigate. Indeed, a precise characterisation of the lit scene reproduced by the head-mounted display is required to control the offered stimuli effectively. Research suggests that the function to transfer the software’s virtual model to the head-mounted display may alter luminance distribution, implying a change in how environments and objects are seen. The problem of the right light distribution reproduction is significant for museum applications . In fact, the lighting of the things can significantly influence their function, value, and intended exhibition. A simple room set up for a painting exhibition was modeled in Unreal Engine, considering the walls black painted and the light sources calibrated, to understand how the light is distributed in the game engine and the headset. The analysis was carried out by comparing the luminance values computed with the game engine with those measured in the headset using a videophotometer. The luminance and the luminance ratio values were evaluated on the surface of the painting with different reflectance values and the quantity of light reaching the surfaces. The effects of the function used to transfer the virtual model into the headset on the luminance values were also investigated. Results highlight that: i) the luminance values are transferred linearly to the headset, whatever the reflectance and colour are, if the function for the model transfer is disabled, and ii) surface reflectance values do not affect the luminance ratios of the scene shown in the headset.