Mehrdad Panahpour Tehrani

Bio: Mehrdad Panahpour Tehrani is an academic researcher from Nagoya University. The author has contributed to research in topics: View synthesis & Depth map. The author has an hindex of 16, co-authored 70 publications receiving 945 citations. Previous affiliations of Mehrdad Panahpour Tehrani include ULTra.

Free-Viewpoint TV

Abstract: Free-viewpoint television (FTV) is an innovative visual media that enables us to view a three-dimensional (3-D) scene by freely changing our viewpoints. We proposed the concept of FTV and constructed the world???s first real-time system including the complete chain of operation from image capture to display. We also carried out the FTV on a single personal computer (PC) and a mobile player. FTV is based on the ray-space method that represents one ray in real space with one point in the ray-space. We have developed several types of ray capture systems and interfaces such as a 360° capture/ray-reproducing display. FTV is regarded as the ultimate 3DTV, since it can generate infinite number of views. Thus, FTV is the key to immersive communication. Regarding FTV as the most challenging 3-D media, the Motion Picture Experts Group (MPEG) has been conducting its international standardization activities. This article reviews FTV and its related technologies.

FTV for 3-D Spatial Communication

Abstract: Free-viewpoint TV (FTV) is cutting the frontier of audiovisual communications. FTV is an innovative media that enables us to view 3-D space by freely changing our viewpoints. It also allows us to listen at any listening point in the 3-D space. Since FTV transmits all audiovisual information of the 3-D space, it can reconstruct an audiovisual replica of the 3-D space anywhere and anytime over distance and time. For video, FTV captures a part of rays in 3-D space by using many cameras, and the other rays that are not captured are obtained by interpolating the captured rays. We constructed real-time FTV systems including the complete chain of operation from image capture to display. We also carried out FTV on a laptop computer and a mobile player. For audio, two kinds of free listening-point systems are demonstrated. MPEG regarded FTV as the most challenging 3-D media and has been conducting its international standardization activities. The first phase of FTV was multiview video coding (MVC) and the second phase of FTV is 3-D video (3DV). MVC enables the efficient coding of multiple camera views and was completed in 2009. MVC has been adopted by Blu-ray 3-D. 3DV is a standard that targets serving a variety of 3-D displays and its call for proposals was issued in March 2011.

High-speed-camera image processing based LED traffic light detection for road-to-vehicle visible light communication

Abstract: As one of ITS technique, a new visible light road-to-vehicle communication system at intersections is proposed. In this system, the communication between a vehicle and an LED traffic light is conducted using an LED traffic light as a transmitter, and an on-vehicle high-speed camera as a receiver. The LEDs in the transmitter emit light in high frequency and those emitting LEDs are captured by the high-speed camera for making communication. Here, the luminance value of LEDs in the transmitter should be captured in consecutive frames to achieve effective communication. For this purpose, first the transmitter should be found, then it should be tracked in consecutive frames by processing the images from the high-speed camera. In this paper, we propose new effective algorithms for finding and tracking the transmitter, which result in a increased communication speed, compared to the previous methods. Experiments using appropriate images showed the effectiveness of the proposals.

Vision-Based Traffic Sign Detection and Analysis for Intelligent Driver Assistance Systems: Perspectives and Survey

Abstract: In this paper, we provide a survey of the traffic sign detection literature, detailing detection systems for traffic sign recognition (TSR) for driver assistance. We separately describe the contributions of recent works to the various stages inherent in traffic sign detection: segmentation, feature extraction, and final sign detection. While TSR is a well-established research area, we highlight open research issues in the literature, including a dearth of use of publicly available image databases and the over-representation of European traffic signs. Furthermore, we discuss future directions of TSR research, including the integration of context and localization. We also introduce a new public database containing U.S. traffic signs.

3-D Video Representation Using Depth Maps

Abstract: Current 3-D video (3DV) technology is based on stereo systems. These systems use stereo video coding for pictures delivered by two input cameras. Typically, such stereo systems only reproduce these two camera views at the receiver and stereoscopic displays for multiple viewers require wearing special 3-D glasses. On the other hand, emerging autostereoscopic multiview displays emit a large numbers of views to enable 3-D viewing for multiple users without requiring 3-D glasses. For representing a large number of views, a multiview extension of stereo video coding is used, typically requiring a bit rate that is proportional to the number of views. However, since the quality improvement of multiview displays will be governed by an increase of emitted views, a format is needed that allows the generation of arbitrary numbers of views with the transmission bit rate being constant. Such a format is the combination of video signals and associated depth maps. The depth maps provide disparities associated with every sample of the video signal that can be used to render arbitrary numbers of additional views via view synthesis. This paper describes efficient coding methods for video and depth data. For the generation of views, synthesis methods are presented, which mitigate errors from depth estimation and coding.

An Indoor Visible Light Communication Positioning System Using a RF Carrier Allocation Technique

Abstract: We propose a new indoor positioning system utilizing visible light communication. Intensity modulation/direct detection and carrier allocation methods are utilized in the proposed system. Simultaneous three channel transmissions were applied to calculate the receiver's position. The characteristics of the proposed positioning system were investigated through simulation based on the experimental results, and the feasibility of the proposed system was verified by experimentation. The experimental result shows that the average error of estimated positions is reduced to 2.4 cm using adjustment process by normalizing method, which is compared with 141.1 cm without adjustment process.

Real-Time Detection and Recognition of Road Traffic Signs

Abstract: This paper proposes a novel system for the automatic detection and recognition of traffic signs. The proposed system detects candidate regions as maximally stable extremal regions (MSERs), which offers robustness to variations in lighting conditions. Recognition is based on a cascade of support vector machine (SVM) classifiers that were trained using histogram of oriented gradient (HOG) features. The training data are generated from synthetic template images that are freely available from an online database; thus, real footage road signs are not required as training data. The proposed system is accurate at high vehicle speeds, operates under a range of weather conditions, runs at an average speed of 20 frames per second, and recognizes all classes of ideogram-based (nontext) traffic symbols from an online road sign database. Comprehensive comparative results to illustrate the performance of the system are presented.

Free-Viewpoint TV

Abstract: Free-viewpoint television (FTV) is an innovative visual media that enables us to view a three-dimensional (3-D) scene by freely changing our viewpoints. We proposed the concept of FTV and constructed the world???s first real-time system including the complete chain of operation from image capture to display. We also carried out the FTV on a single personal computer (PC) and a mobile player. FTV is based on the ray-space method that represents one ray in real space with one point in the ray-space. We have developed several types of ray capture systems and interfaces such as a 360° capture/ray-reproducing display. FTV is regarded as the ultimate 3DTV, since it can generate infinite number of views. Thus, FTV is the key to immersive communication. Regarding FTV as the most challenging 3-D media, the Motion Picture Experts Group (MPEG) has been conducting its international standardization activities. This article reviews FTV and its related technologies.