Libor Bolecek

Study of the coexistence between ZigBee and Wi-Fi IEEE 802.11b/g networks in the ISM band

The number of wirelessly connected multimedia devices and different communication standards, supported by these devices, is rapidly increasing. However, the appropriate frequency bands (licensed and unlicensed) for data transmission by these standards are very limited. The rising density of wireless networks and their coexistence in the same or adjacent radio frequency (RF) spectrum can significantly decrease the quality of provided services. This paper deals with the study of coexistence between ZigBee (IEEE 802.15.4) and Wireless Fidelity (Wi-Fi) networks, including the IEEE 802.11b/g standards, which operate in the unlicensed Industrial, Scientific and Medical (ISM) band at 2.4 GHz. Firstly, a general simulation model was developed. Secondly, to verify results from simulation by measurement, an appropriate laboratory workplace in anechoic chamber was proposed and realized. Such setup and the measurement principle are briefly described in this paper too. Impact of the IEEE 802.11b/g networks on the ZigBee and vice versa is evaluated by dependence of bit error rate (BER) and error vector magnitude (EVM) on the power imbalance between power levels of considered RF signals, respectively.

BLE device indoor localization based on RSS fingerprinting mapped by propagation modes

Nowadays, Bluetooth Low Energy (BLE) technology has a great attention in the field of wireless localization techniques, especially in the case of indoor scenarios. Study presented in this paper explores BLE localization performance in indoor scenarios based on a received signal strength (RSS). Firstly, we present a Ray-Launching based application to emulate BLE radio frequency (RF) signal propagation in the office environment. Secondly, an appropriate measurement workplace and its setup is proposed to measure RSS values. Obtained results are used to create an RSS-fingerprinting map. Furthermore, accuracy of position determination is calculated and evaluated. Results show advantage of BLE technology for indoor localization purposes (without calibration measurement). However, its performance highly depends on the number of considered BLE nodes and on applied evaluation method (e.g. number of considered sectors).

Study of the performance of RSSI based Bluetooth Smart indoor positioning

Recently, there is a high interest for appropriate systems and methods to localize the position of people and their devices in indoor environments (e.g. home, office, hospital). From technical and economical points of view, Bluetooth Low Energy (BLE) is one of the promising technologies in this field. This paper deals with the study of performances of this technology for these purposes. For the indoor localization, a received signal strength indication (RSSI) method is used. It was tested in ideal (anechoic chamber) and real (in the office) environment conditions. For the measurement campaign and evaluation of the obtained results a generic framework is proposed. Experimental results (simulation vs. measurement) show similar behaviour of the BLE technology in ideal (no signal reflection) and real (multipath propagation) transmission environments.

Fast method for reconstruction of 3D coordinates

The paper deals with the reconstruction of spatial coordinates of an arbitrary point from a scene using two monochromatic images which are in general relation. These two images can be created for example by a stereo camera in practical applications. Calculation is based on the perspective geometry. Search of the point features in each of these images is a fundamental building step to find image correspondence in this procedure. An algorithm for fast elimination of false correspondences which could devastate the scene reconstruction was designed. Well known mathematic relation is used to obtain the fundamental matrix and then reconstruct the 3D coordinates of feature points. Acquisition of 3D coordinates of points in the scene for which it is difficult to find correspondences is more complicated. In the paper, we have proposed a method based on utilization of the relation between the selected point and near features points. The performed experiments confirmed usability of designed procedure.

Study of advanced compression tools for stereoscopic video by objective metrics

Nowadays, there are many kinds of technologies to provide multimedia TV content in different formats and picture quality. Three-dimensional (3D) video is one of the next generation TV services with specific features from the video image quality point of view. Naturally, efficient compression tools enabling significant bit rate reduction to ease 3D video distribution are an integral part of any practical 3D video system implementation. In this paper, we present a study of recent and upcoming compression tools for stereoscopic videos. We consider H.264 Advanced Video Coding (AVC), H.264 Annex H - Multiview Video Coding (MVC), H.265 High Efficiency Video Coding (HEVC) and H.265 Annex G - Multiview High Efficiency Video Coding (MV-HEVC) video coding formats to process stereoscopic videos with different properties. To compare the performance of considered compression tools, we provide an analysis of the encoded/decoded stereoscopic video quality using objective metrics.

3D Content Acquisition and Coding

This chapter starts by addressing the impact of the inaccurate camera system alignment on the spatial reconstruction accuracy and stereo perception. An experimental study is described, using a stereoscopic camera setup and its deterministic relations derived by trigonometry, spatial model, and basic stereoscopic formulas. The significance of errors that can occur for possible cameras system setup is analyzed in order to find the appropriate settings and physical constraints of the camera system, which minimize the error. Then, the chapter presents an overview of the compression tools used in current stereoscopic and multiview video encoders. It includes the stereoscopic frame-compatible formats using spatial multiplex in the side-by-side and top-and-bottom fashion; the video plus depth representation, the layered coding approach, and multiview encoding. Furthermore, an extension of multiview video compression for the arbitrary camera arrangements is presented. The current status of MPEG exploration experiments of next-generation video codec technologies is also outlined in the last section. First, the UltraHD compression performance beyond HEVC is presented and second, the recent developments in HDR/WCG format conversion and coding are presented. Finally, the testing procedures and 3D projection formats for 360° video are addressed.

Extending of the Kinect device functionality and the corresponding database

This paper deals with a creation of the RGB-D database by using Microsoft Kinect device. One of the main uses of Kinect is measurement and subsequent creation the so-called depth maps of the 3D scenes. The maps obtained by Kinect can be improved. Existence of databases suitable for the experiment is very important for research. One of the possible research directions is use of infrared version of the investigated scene for improvement of the depth map. However, the databases of the Kinect data which would contain the corresponding infrared images do not exist. Therefore, our aim was to create such database. We want to increase the usability of the database by adding stereo images. Moreover, the same scenes were captured by Kinect v2. It was also investigated the impact of simultaneous use Kinect v1 and Kinect v2 to improve depth map investigated the scene. The database contains sequences of objects on turntable and simple scenes containing several objects.

The estimation of a depth map using spatial continuity and edges

This paper deals with creating depth maps from two images. The initial map is created using the sum of the absolute differences of the each image points neighborhood. Many discontinuities are in this map. Therefore, we have to use some approach for its improvement. The proposed method utilizes a combination of a few approaches. The first approach is based on the assumption of continuity of the depth map in rows and utilizing information about edges in images. We designed rules for filling zero areas in the initial depth map. The second step uses disparity of significant points found in zero areas. The significant points are found by the algorithm Speeded Up Robust Features (SURF). The applicability of the proposed method is demonstrated on a few images from Middlebury Stereo Datasets. In the future, we will execute subjective tests for examining the influence of the depth map to the evaluation of the spatial effect. The proposed methods will be used as tool for depth maps generation with various quality.

Modified method for optimization of image registration

The paper deals with the topic of image registration. Image registration is important operation in image processing. Registration accuracy has essential importance for the quality of further processing of images in e.g. 3D processing. This paper provides one new cost function. Experimental results performed in this work show that this newly proposed function has the advantage of low complexity in comparison with the present-day methods. The function has good reliability and fast convergence. The paper presents a specific modification of particle swarm optimization for the evaluation of the results as well. The paper provides a novel approach using pseudo-color representation of image. Pseudo-color representation offers high contrast in images.