Structured Light of Flickering Patterns Having Different Frequencies for a Projector-Event-Camera System

Projector-camera systems have long been used in measuring three-dimensional shapes. Most projector-camera systems can only be used in dark rooms because frame-based cameras are not robust against strong ambient light and are difficult to obtain correspondence to the image pixels of the projector. Recently, event cameras, which can detect the direction of luminance change, have received attention in the field of computer vision. When considering the many advantages of event cameras, this study focuses on their wide dynamic range (120 vs. 40 dB of a frame-based camera) and their ability to detect fast luminance changes. Our objective is to realize a projector-camera system that combines the event camera with a projector under the strong ambient light. Specifically, this study proposes a new structured light that combines different frequencies of flickers to acquire the correspondence between the image pixels of the event camera and the projector. This method does not rely on the co-axial frame-based measurement and synchronization mechanism between projector and camera and is thus applicable to most general event cameras. Experiments confirm that the proposed method obtains the correspondence robustly with reasonable accuracy in a bright room (up to 2,600 lux) under general indoor lighting and additional light projection.