An Adaptive Spread Spectrum (SS) Synchronous Data Hiding Strategy for Scalable 3D Terrain Visualization

International audienceThe diversity of clients in today's network environment compels us to think about solutions that more than satisfy their needs according to their resources. For 3D terrain visualization this translates into two main requirements, namely the scalability and synchronous unification of a disparate data that requires at least two files, the texture image and its corresponding digital elevation model (DEM). In this work the scalability is achieved through the multiresolution discrete wavelet transform (DWT) of the JPEG2000 codec. For the unification of data, a simple DWT-domain spread spectrum (SS) strategy is employed in order to synchronously hide the DEM in the corresponding texture while conserving the JPEG2000 standard file format. Highest possible quality texture is renderable due to the reversible nature of the SS data hiding. As far as DEM quality is concerned, it is ensured through the adaptation of synchronization in embedding that would exclude some highest frequency subbands. To estimate the maximum tolerable error in the DEM according to a given viewpoint, a human visual system (HVS) based psycho-visual analysis is being presented. This analysis is helpful in determining the degree of adaptation in synchronization

A Lossy JPEG2000-based Data Hiding Method for Scalable 3D Terrain Visualization

International audienceThe data needed for 3D terrain visualization consists, essentially, of a texture image and its corresponding digital elevation model (DEM). A blind data hiding method is proposed for the synchronous unification of this disparate data whereby the lossless discrete wavelet transformed (DWTed) DEM is embedded in the tier-1 coded quantized and DWTed Y component of the texture image from the lossy JPEG2000 pipeline. The multiresolution nature of wavelets provides us the scalability that can cater for the diversity of client capacities in terms of computing, memory and network resources in today's network environment. The results have been interesting and for a bitrate as low as $0.012$ bit per pixel (bpp), a satisfactory visualization was realized. We compare the obtained results with those of a previous method that interrupt the lossless JPEG2000 codec immediately after the DWT step and embeds lossless DWTed DEM in the reversibly DWTed Y component of texture. The proposed method proved to be more effective in the sense that for the same bitrate one observed lesser quality loss for respective resolutions

An Efficient Data-hiding Method Based on Lossless JPEG2000 for a Scalable and Synchronized Visualization of 3D Terrains

International audienceReal-time on-line 3D visualization of terrain is a memory intensive process accompanied by considerably large data transfer across the network and thus data compression is inevitable. The upcoming standard of JPEG2000 is well suited for such network based transfers since it offers the additional advantage of resolution scalability resulting in incremental improvement of quality. The 3D visualization process is, essentially, the linking of the texture image with the terrain geometry obtained from DEM; the data are heterogeneous and normally involves more than one file. This work is concerned with the interleaving of these files into one jp2 file in a synchronized way so that the file format is conserved for compliance to the JPEG2000 standard. This synchronization is achieved by using a scalable data hiding method to embed the lossless wavelet transformed DEM in the corresponding lossless JPEG2000 coded texture. For the DEM and the texture, the level of transform is the same. With this approach the 3D visualization is efficient even if a small fraction of the initial data is transmitted

Scalable Data Hiding for Online Textured 3D Terrain Visualization

International audienceA method for 3D scalable visualization, in a client/server environment is presented. The main idea presented in this paper is to increase the quality of 3D visualization for low bit rate transmission. All informations like texture, digital elevation model and projection systems are merged into a single file. The integration is achieved via data hiding whereas the scalability is realized through the multiresolution nature of JPEG2000 encoding. The embedding step is done in the lossless DWT domain. The strategy is flexible and it is up to the user to decide the level of transform of texture and DEM. In this context a comparison between various possibilities is presented by applying the method to a practical example. It is shown that a very good visualization can be realized with even a tiny fraction of the encoded coefficients

WAVELET BASED DATA HIDING OF DEM IN THE CONTEXT OF REALTIME 3D VISUALIZATION (Visualisation 3D Temps-Réel à Distance de MNT par Insertion de Données Cachées Basée Ondelettes)

The use of aerial photographs, satellite images, scanned maps and digital elevation models necessitates the setting up of strategies for the storage and visualization of these data. In order to obtain a three dimensional visualization it is necessary to drape the images, called textures, onto the terrain geometry, called Digital Elevation Model (DEM). Practically, all these information are stored in three different files: DEM, texture and position/projection of the data in a geo-referential system. In this paper we propose to stock all these information in a single file for the purpose of synchronization. For this we have developed a wavelet-based embedding method for hiding the data in a colored image. The texture images containing hidden DEM data can then be sent from the server to a client in order to effect 3D visualization of terrains. The embedding method is integrable with the JPEG2000 coder to accommodate compression and multi-resolution visualization. Résumé L'utilisation de photographies aériennes, d'images satellites, de cartes scannées et de modèles numériques de terrains amène à mettre en place des stratégies de stockage et de visualisation de ces données. Afin d'obtenir une visualisation en trois dimensions, il est nécessaire de lier ces images appelées textures avec la géométrie du terrain nommée Modèle Numérique de Terrain (MNT). Ces informations sont en pratiques stockées dans trois fichiers différents : MNT, texture, position et projection des données dans un système géo-référencé. Dans cet article, nous proposons de stocker toutes ces informations dans un seul fichier afin de les synchroniser. Nous avons développé pour cela une méthode d'insertion de données cachées basée ondelettes dans une image couleur. Les images de texture contenant les données MNT cachées peuvent ensuite être envoyées du serveur au client afin d'effectuer une visualisation 3D de terrains. Afin de combiner une visualisation en multirésolution et une compression, l'insertion des données cachées est intégrable dans le codeur JPEG 2000

JPEG2000-Based Data Hiding to Synchronously Unify Disparate Facial Data for Scalable 3D Visualization

International audienceWe present a scalable encoding strategy for the 3D facial data in various bandwidth scenarios. The scalability, needed to cater diverse clients, is achieved through the multiresolution characteristic of JPEG2000. The disparate 3D facial data is synchronously unified by the application of data hiding wherein the 2.5D facial model is embedded in the corresponding 2D texture in the discrete wavelet transform (DWT) domain. The unified file conforms to the JPEG2000 standard and thus no novel format is introduced. The method is effective and has the potential to be applied in videosurveillance and videoconference applications

Recent Advances in Signal Processing

The signal processing task is a very critical issue in the majority of new technological inventions and challenges in a variety of applications in both science and engineering fields. Classical signal processing techniques have largely worked with mathematical models that are linear, local, stationary, and Gaussian. They have always favored closed-form tractability over real-world accuracy. These constraints were imposed by the lack of powerful computing tools. During the last few decades, signal processing theories, developments, and applications have matured rapidly and now include tools from many areas of mathematics, computer science, physics, and engineering. This book is targeted primarily toward both students and researchers who want to be exposed to a wide variety of signal processing techniques and algorithms. It includes 27 chapters that can be categorized into five different areas depending on the application at hand. These five categories are ordered to address image processing, speech processing, communication systems, time-series analysis, and educational packages respectively. The book has the advantage of providing a collection of applications that are completely independent and self-contained; thus, the interested reader can choose any chapter and skip to another without losing continuity

Enhanced 3D terrain visualization process using game engine

Recently, many information visualization regarding terrain use 2D maps which include shading and lines to show the terrain. However, the emerging 3D terrain visualization technologies and software may produce a lot of terrain information. This emerging technology is also concurrent with the growth of game engines. As for this study, Unity3D, one of these game engines, has built-in terrain engine that provides 3D terrain visualization. Moreover, this engine provides the ability to be able to publish as web application for the online environment. Based on the literature review, there are studies related to terrain visualization developed using game engines, however, majority focuses on the capability of terrain visualization in an offline environment. None of these studies focus on the performance of the 3D visualization process in an online environment. Thus, the aim of this study is to enhance the process of generating 3D terrain visualization with GIS data generated from the Unity3D game engine in an online environment. The results of the performance are compared with two different situation that is online and offline. Several experiments are conducted and performances are measured based on loading time, response time, frames per second (FPS), memory usage and CPU usage of different terrain data types and size. The study adopts design research process that is comprised of problem identification from literature review, solution development by using the process to develop the prototype needed, and evaluation by comparing the output of the visualization process. The findings show that the process of enhancing 3D terrain visualization with GIS data generated from the Unity3D game engine in offline environment is better compared to those online. This is due to the compression and the need for Unity3D web player to make contact with the Unity server for authentication and also for visualization during online. Furthermore, operating system resource needs to be used before it goes online. The main finding of this study is the new algorithm of enhancing 3D terrain visualization process using Unity3D game engine. The algorithm can be divided into three processes which are terrain data reading, terrain data conversion, and terrain data processing. It may assist the developer on how to enhance the process of developing web-based 3D terrain visualization using Unity3D game engine

Scalable 3-D Terrain Visualization Through Reversible JPEG2000-Based Blind Data Hiding

Abstract—In this paper a new method is presented for 3-D terrain visualization via reversible JPEG2000-based blind data hiding with special focus on data synchronization and scalability. Online real-time 3-D terrain visualization involves considerable amount of data. The process is essentially the mapping of the aerial photograph, called texture, onto its corresponding digital elevation model (DEM) implying at least two distinct data inputs. The presence of large disparate data necessitates a compression strategy on one hand and the integration of the DEM and texture into one unit on the other. Whilst the compression must accommodate the scalability requirement originated by the diversity of clients, the unification of data ought to be synchronous. For scalability this paper relies on the multiresolution nature of the DWT-based JPEG2000 standard whereas the synchronized unification of DEM with the texture is realized by the application of a perceptually transparent data hiding strategy in the DWT domain. The proposed method is blind in the sense that only a secret key, if any, and the size of the original DEM are needed to extract the data from the texture image. We believe that this is one of the pioneering methods to propose scalable embedding of DEM in the texture image. The method is cost effective, in terms of memory and bandwidths, which is an advantage, especially, in real-time environments when quicker transfer of data is required. The results of a 3-D visualization simulation effected with our method were encouraging and gave a useful insight to the effectiveness of our method in various bandwidth scenarios. Index Terms—3-D visualization, data hiding, data synchronization

Exploiting Spatio-Temporal Coherence for Video Object Detection in Robotics

This paper proposes a method to enhance video object detection for indoor environments in robotics. Concretely, it exploits knowledge about the camera motion between frames to propagate previously detected objects to successive frames. The proposal is rooted in the concepts of planar homography to propose regions of interest where to find objects, and recursive Bayesian filtering to integrate observations over time. The proposal is evaluated on six virtual, indoor environments, accounting for the detection of nine object classes over a total of ∼ 7k frames. Results show that our proposal improves the recall and the F1-score by a factor of 1.41 and 1.27, respectively, as well as it achieves a significant reduction of the object categorization entropy (58.8%) when compared to a two-stage video object detection method used as baseline, at the cost of small time overheads (120 ms) and precision loss (0.92).</p