A Visual Distance Approach for Multicamera Deployment With Coverage Optimization

This paper proposes a visual distance approach for a multicamera deployment through parallel coverage optimization over three-dimensional (3-D) space to inspect 3-D objects. The key idea is the proposal of a new “visual distance” between a single camera and a scene point, which takes into account multiple coverage criteria. Specifically, the effective visual sensing area of a single camera is expressed by a 4-D geometric object, which is composed of a 3-D visual frustum and an extra dimension for the acceptable view angle. An anisotropic projective transformation is applied to transform this 4-D geometric object into a 4-D unit cube, based on which a new visual coverage measure called “visual distance” is proposed using the infinity norm. It is shown that this new measure is capable of characterizing the coverage level of a task point in a quantitative way. Based on the visual distance, a coverage strength model and a new type of scene partition, called visual Voronoi partition, are established, and then a parallel gradient optimization approach is developed to achieve optimal coverage performance of a multicamera network. Comparative simulation and experimental results are provided to show the effectiveness and superior performance of the proposed approach.

I. Introduction

As a typical kind of noncontact exteroceptive sensors, visual cameras present several extraordinary advantages, including rich information, low weight, small size, low power consumption, and low cost. Due to these attractive features, vision-based applications become more and more pervasive in the field of robotics, automation, and mechatronics [1]–[3]. Yet, a single camera cannot fully cover a three-dimensional (3-D) object due to its limited field of view (FOV) and visual occlusion. Hence, it is necessary to deploy a multicamera network [4] for many tasks, such as product quality inspection [5], dimension measurement [6], scene reconstruction [7], [8], visual surveillance [9], and so on.