Hiding a Second Appearance in a Physical Relief Surface

Abstract

Abstract. We present a novel information hiding process that couples geometrical modeling with automated 3D fabrication for creating hiddenappearance reliefs. Our relief surface produces a first grayscale appearance visible by simple direct illumination and a second grayscale appearance ensured to be visible when the relief is lit by a digital projector with a specifically designed pattern and from a particular direction. The two appearances/images can be different yet embedded in the same physical relief. Since the second appearance appears only on demand, it could be used to hide a second image, a company logo, or a watermark image, for instance. Our novel method calculates a relief surface that maintains the properties needed for producing a second (hidden) appearance while also ensuring the first appearance is visible under normal direct illumination. Our experiments show that our method robustly produces reliefs with two arbitrary desired appearances.

Survey on computational 3D visual optical art design

“…The bas-reliefs they generate are closer to the target image under the specified illumination condition. The works of Alexa and [36]. They produced some results to demonstrate the effectiveness of their algorithm (Fig.…”

“…Alexa and Matusik [35], Chao and Aliaga [36], and Zhang et al [37] researched the generation of bas-relief under specific light sources. The algorithm proposed by Zhang et al [37] considers the effect of lighting on the appearance of bas-reliefs.…”

InfraStructs

“…Techniques for embedding spatial information in digitally fabricated objects have to date focused on surface geometry [Alexa and Matusik 2010;Aliaga and Atallah 2009;Chao and Aliaga 2013;Hašan et al 2010;Weyrich et al 2009]. We are unaware of any prior work that allows machinereadable tags to be embedded inside of a digitally fabricated object.…”