Manufacturing Layered Attenuators for Multiple Prescribed Shadow Images

We present a practical and inexpensive method for creating physical objects that cast different color shadow images when illuminated by prescribed lighting configurations. The input to our system is a number of lighting configurations and corresponding desired shadow images. Our approach computes attenuation masks, which are then printed on transparent materials and stacked to form a single multi‐layer attenuator. When illuminated with the input lighting configurations, this multi‐layer attenuator casts the prescribed color shadow images. Alternatively, our method can compute layers so that their permutations produce different prescribed shadow images under fixed lighting. Each multi‐layer attenuator is quick and inexpensive to produce, can generate multiple full‐color shadows, and can be designed to respond to different types of natural or synthetic lighting setups. We illustrate the effectiveness of our multi‐layer attenuators in simulation and in reality, with the sun as a light source.