Harvard University

Figure 1: We introduce a reflectance display: a dynamic digital array of dots, each of which can independently display a custom, time-varying reflectance function. The display passively reacts to illumination and viewpoint changes in real-time, without any illumination-recording sensors, head tracking, or on-the-fly rendering. In this example the time-varying reflectance functions create a “reflectance video” that gives the illusion of a dynamic 3D model being physically-shaded by the room’s ambient lighting. The top row shows a time-sequence of photographs of the dynamic display from a stationary viewpoint under fixed ambient lighting, and the bottom row shows how the display reacts to changes in ambient lighting by passively inducing the appropriate 3D shading effects. We present a reflectance display: a dynamic digital display capable of showing images and videos with spatially-varying, user-defined reflectance functions. Our display is passive: it operates by phase-modulation of reflected light. As such, it does not rely on any illu-mination recording sensors, nor does it require expensive on-the-fly rendering. It reacts to lighting changes instantaneouasly and con-sumes only a minimal amount of energy. Our work builds on the wave optics approach to BRDF fabrication of Levin et al. [2013]. We replace their expensive one-time hardware fabrication with a programable liquid crystal spatial light modulator, retaining high resolution of approximately 160 dpi. Our approach enables the display of a much wider family of angular reflectances, and it al-lows the display of dynamic content with time varying reflectance properties—“reflectance videos”. To facilitate these new capabili-ties we develop novel reflectance design algorithms with improved resolution tradeoffs. We demonstrate the utility of our display with a diverse set of experiments including display of custom reflectance images and videos, interactive reflectance editing, display of 3D content reproducing lighting and depth variation, and simultaneous display of two independent channels on one screen