Kazumasa Yamazawa

Omnidirectional imaging with hyperboloidal projection

Described here is an image sensor with a hyperboloidal mirror for vision based navigation of a mobile robot. Its name is HyperOmni Vision. This sensing system can acquire an omnidirectional view around the robot, in real-time, with use of a hyperboloidal mirror.

Telepresence by Real-Time View-Dependent Image Generation from Omnidirectional Video Streams

This paper describes a new approach to telepresence which realizes virtual tours into a visualized dynamic real world without significant time delay. We propose a novel concept ofinstantourwhich enables us to instantly look around a visualized space of a dynamic real world. Theinstantouris realized by the following two steps: (1) video-rate omnidirectional image acquisition and (2) real-time view-dependent perspective image generation from an omnidirectional video stream. The proposed technique is applicable to real-time telepresence in the situation where the real world to be seen is far from an observation site, because the time delay from the change of viewing direction to the change of displayed image does not depend on the actual distance between both sites. Moreover, multiple users can look around from a single viewpoint in a visualized dynamic real world in different directions at the same time. The proposed technique is also useful for another type of telepresence which uses recorded omnidirectional video streams. We have developed a prototype of virtualinstantoursystem and have successfully experimented with real dynamic scenes.

Obstacle detection with omnidirectional image sensor HyperOmni Vision

Described here is an image sensor with a hyperboloidal mirror for vision based navigation of a mobile robot. Its name is HyperOmni Vision. This sensing system can acquire an omnidirectional view around the robot, in real-time, with use of a hyperboloidal mirror. The authors show a prototype of a mobile robot system with HyperOmni Vision and a method for estimating the motion of the robot and finding unknown obstacles.

Generation of high-resolution stereo panoramic images by omnidirectional imaging sensor using hexagonal pyramidal mirrors

We have developed a high-resolution omnidirectional stereo imaging sensor that can take images at video-rate. The sensor system takes an omnidirectional view by a component constructed of six cameras and a hexagonal pyramidal mirror and acquires stereo views by symmetrically connecting two sensor components. The paper describes a method of generating stereo panoramic images by using our sensor. First, the sensor system is calibrated; that is, twelve cameras are correctly aligned with pyramidal mirrors and the Tsais method restores the radial distortion of each camera image. Stereo panoramic images are then computed by registering the camera images captured at the same time.

Rolling motion estimation for mobile robot by using omnidirectional image sensor HyperOmniVision

Described here is a method for estimating a rolling motion of a mobile robot from optical flows. We have proposed an image sensor with a hyperboloidal mirror for vision based navigation of the mobile robot. Its name is HyperOmniVision. This sensing system can acquire an omnidirectional view around the robot, in real-time, with use of the hyperboloidal mirror. The radial component of optical flow in HyperOmniVision has a periodic characteristic. The proposed method makes use of this characteristic to estimate robustly the rolling motion of the robot.

Networked video surveillance using multiple omnidirectional cameras

Remote surveillance is widely utilized in banks, shops, offices, at home and so on. In most conventional remote surveillance systems, fixed or active cameras with a narrow field of view are generally used in order to acquire an image of the remote site. This paper proposes a new networked surveillance system. The proposed surveillance system, which uses multiple omnidirectional cameras and network, is based on a server/client model: the server computers, each of which is connected to an omnidirectional video camera, are placed in the surveillance area and the client computer is placed on the user side. The servers detect moving objects and estimate their directions from sensors. The client estimates object positions from their directions received from the servers and presents object-centered perspective images to the user. In experiments, the implemented proposed system can do those at real-time.

Construction of an immersive mixed environment using an omnidirectional stereo image sensor

Recently virtual reality (VR) systems have been incorporating rich information available in the real world into VR environments in order to improve their reality. This stream has created the field of mixed reality which seamlessly integrates real and virtual worlds. This paper describes a novel approach to the construction of a mixed environment. The approach is based on capturing the dynamic real world by using a video-rate omnidirectional stereo image sensor. The mixed environment is constructed of two different types of models: (1) texture-mapped cylindrical 3-D model of dynamic real scenes and (2) 3-D computer graphics (CG) model. The cylindrical 3-D model is generated from full panoramic stereo images obtained by the omnidirectional sensor that uses a pair of hexagonal pyramidal mirrors and twelve CCD cameras. A prototype system has been developed to confirm the feasibility of the proposed method, in which panoramic binocular stereo images of the mixed environment are projected on a cylindrical immersive display depending on users viewpoint in real time.

HyperOmni vision: Visual navigation with an omnidirectional image sensor

For robot navigation, we need sensor information as to the condition of the environment around the robot. In this paper, we describe an omnidirectional vision system (HyperOmni Vision) using a hyperboloidal mirror and describe its distinctive features, together with a visual navigation method using HyperOmni Vision. In existing omnidirectional vision systems, since the optical system does not use center projection, an independent method of acquiring the visual information is required. However, since the omnidirectional vision system using a hyperboloidal mirror has an omnidirectional visual field and the optical characteristic of center projections, its images can be transformed into images taken directly with an ordinary camera. For this reason, it can produce images suitable for processing, and not only independent techniques, but also conventional image processing technology can be utilized. We will report here the configuration, distinctive features, and characteristics of the optical system of HyperOmni Vision and describe a mobile robot using HyperOmni Vision and its techniques of movement estimation and obstacle detection by template matching.

Real-time generation and presentation of view-dependent binocular stereo images using a sequence of omnidirectional images

This paper presents a new method to generate and present arbitrarily directional binocular stereo images from a sequence of omnidirectional images. A sequence of omnidirectional images is taken by moving an omnidirectional image sensor in a static real environment. The motion of the omnidirectional image sensor is constrained to a plane. The sensors route and speed are known. In the proposed method, a fixed length of the sequence is buffered in a computer to generate arbitrarily directional binocular stereo images by combining captured rays. Using the method a user can look around a scene in the distance with rich 3D sensation without significant time delay. This paper describes the principle of real-time generation of binocular stereo images. In addition, we introduce a prototype telepresence system of view-dependent stereo image generation and presentation.

Stabilization for mobile robot by using omnidirectional optical flow

Described here is a method for estimating rolling and swaying motions of a mobile robot from optical flows. We have proposed an image sensor with a hyperboloidal mirror for vision based navigation of the mobile robot. Its name is HyperOmni Vision. This sensing system can acquire an omnidirectional view around the robot, in real-time, with use of the hyperboloidal mirror. The radial component of optical flow in HyperOmniVision has a periodic characteristic. The circumferential component of optical flow has a symmetric characteristic. The proposed method makes use of these characteristics to estimate robustly the rolling and swaying motions of the robot.