Structures, Pointing, And Control Engineering Laboratory


Aerospace Information Server

This research activity establishes an Aerospace Information Server to collect, manage, and analyze aerospace information in different categories with different formats, and make it available to the aerospace community and the general public. The following points of interest are the focus of this research activity:

•       Telescope imagery;

•       Decentralized control signals for precision pointing of the telescope;

•       Telescope animation for distance control; and

•       Visualization for flight dynamics and control, among other matters.

The server is designed to be accessible through the Internet or other special-purpose networks to support interactive query, scalable image browsing, and on-line simulation. One example of the basic structure of the server is depicted in Figure 1. Note that different levels of accessibility may be permitted to users with different authorities.

Interactive query is a basic function for any information system, but creating an efficient query is particularly challenging in a multimedia database. To improve the accuracy and efficiency of query, this research activity employs advanced data-mining technology in the Aerospace Information Server. In order to disseminate the rich multimedia content in the information server, representative features of images or video frames can be extracted and stored in the database. The system incorporates the Gabor function in the feature extraction mechanism, as it can be used to model the response of simple cells in visual cortex, and fast-searching algorithms are designed to speed up the on-line query.

In addition to interactive query, the proposed information server is designed to support a novel scenario for scalable browsing. Most current information systems/databases on the Internet implement scalable browsing by storing multiple versions of images of different resolutions or quality. Problems associated with this browsing scheme include inefficient storage and lack of bandwidth adaptivity. Using scalable compression technologies, the Investigators can solve this problem. In the proposed scheme, only one version of a compressed image is stored on the server. Using progressive coding/decoding, the compressed image video can be decoded at any bit rate to support arbitrary quality requirements. The Investigators design an adaptive rate control module to work with the scalable compression to allocate bandwidth dynamically according to the users' requirements and traffic conditions. This browsing scheme is able to meet different Quality of Services (QoS) requirements in a heterogeneous network, as illustrated by Figure 2. It can also improve the bandwidth utility throughout the system.

Rich functionality is another advantage of the proposed Aerospace Information Server. Unlike the current aerospace database, the information server is able to analyze and process stored data and images for research and education purposes. For example, the Investigators use on-line image processing tools to analyze the astronomical images, and incorporate astrophysical models to develop a simulation toolbox for the convenience of aerospace research or teaching. Key technologies involved include: High-performance computation, multimedia database design, data-mining technologies including classification and feature extraction, content-based query (object-tracking), multi-resolution image display, and real-time streaming to distribute the stored images to multiple users.

Figure 1 - Aerospace Information Server Flowchart


Figure 2 - Server Overview


Figure 3 - Progressive File Compression