A virtual city, a virtual reality system to display an urban scene, is one of the most promising tools for ITS applications, including car navigation aids, shopping guides, and city planning, to name a few. This paper overviews our effort to create virtual cities through a sequence of images obtained with vision/range sensors. Our virtual city consists not of only stationary buildings but also of running and parked vehicles, which reflect the current activities in the real city. The first part of this paper describes how to construct still building images from a sequence of images. Here, we focus on methods employing an omni image camera that acquires images containing rays of 360 degrees viewing directions. The second part describes a system to display vehicle movement in the virtual city based on the image sequence given with a monitoring TV camera at an intersection. It also describes a preliminary step toward displaying illegal parked vehicles from information collected by a probe car.

We have built an active omni-directional range range sensor that can obtain an omni-directional depth data through the use of a laser conic plane and a conic mirror. In the navigation of the mobile robot, the proposed sensor system makes a laser conic plane by rotating the laser point source at high speed which creates a two-dimensional depth map, in real time, once an image is captured. Also, since the proposed sensor system measures the actual distance of the target objects, it is able to apply the proposed sensor system to other measurement tasks.

In this paper, we present a digital scheme for fast VLSI range imaging sensor, which is a modification of the analog scheme of existing sensor implemented by T. Kanade. Instead of reading timing information in analog manner, we use a digital scheme which has several advantages over the analog scheme, including area saving, insusceptibility to noise and other undesirable effects. We have implemented a prototype to test feasibility and present its experimental result.