Effects of view-dependent highlights and specular intensity on gloss perception in projection mapping

Current projection mapping (PM) techniques perform well at manipulating matte appearances but struggle to convincingly reproduce specular materials. In typical PM, projected highlights are fixed to the surface coordinates, causing observers to misinterpret them as surface paint rather than optical reflections. Although view-dependent highlight motion is known to enhance gloss perception on displays, its applicability to PM remains unclear because displays present emitted light, whereas PM relies on reflected light from physical surfaces. In this study, we examined the effects of specular highlight motion and specular intensity on perceived gloss in PM. Participants completed a comparative gloss judgment task and a specular intensity matching task using a view-dependent PM system. We tested six conditions combining the presence of highlight motion with three levels of specular intensity. Results showed that the contribution of highlight motion was smaller than that of specular intensity. These findings suggest that gloss cues reported in display based studies may not directly apply to PM, motivating further investigation under projection based presentation.