Optical Surveillance Research Articles

Application and reliability of a fiber optical surveillance system for a stay cable bridge

In this paper we report on the application of a fiber optical system for the surveillance of a new stay cable bridge. The novelty of the bridge is the use of cables made of carbon-fiber-reinforced polymer wires. This new concept in bridge construction requires monitoring of the cables to ensure their reliability. The results of an observation period of more than six months during the construction are presented. Tests of the reliability of the fiber optical monitoring system are discussed.

Three-dimensional vector estimation for subcomponents of space object imagery

We describe a model-based image analysis system that automatically estimates the 3-D orientation vectors of satellites and their subcomponents by analyzing images obtained from a ground-based optical surveillance system. We adopt a two-step approach: pose estimates are derived from comparisons with a model database and pose refinements are derived from photogrammetric information. The model database is formed by representing each available training image by a set of derived geometric primitives. To obtain fast access to the model database and to increase the probability of early successful matching, a novel index-hashing method is introduced. An affine point-matching method is also introduced for improving system performance on a wide variety of satellite shapes. We present recent results, which include our efforts at isolating and estimating orientation vectors from degraded imagery on a significant database of satellites.

Static Mapping of Functional Programs: An Example in Signal Processing

Complex signal‐processing problems are naturally described by compositions of program modules that process streams of data. In this article we discuss how such compositions may be analyzed and mapped onto multiprocessor computers to effectively exploit the massive parallelism of these applications. The methods are illustrated with an example of signal processing for an optical surveillance problem. Program transformation and analysis are used to construct a program description tree that represents the given computation as an acyclic interconnection of stream‐processing modules. Each module may be mapped to a set of threads run on a group of processing elements of a target multiprocessor. Performance is considered for two forms of multiprocessor architecture, one based on conventional DSP technology and the other on a multithreaded‐processing element design.

Tracking periodic inputs using sampled compensators

There are many control system applications where there is a requirement to track a reference signal which is periodic. Examples of this type of application include scanning systems such as those for optical surveillance or radar tracking, and industrial automation systems where robots repetitively follow set trajectories. The conventional integral compensator gives zero error at steady state by providing an infinite gain in the forward path of a control compensator. A compensator based on a digital comb filter can be used to provide infinite gain at a set of harmonically related frequencies. In this way it is possible to provide a digital comb compensator which gives zero steady-state error to a periodic input. The poles of the compensator are determined by the tracking requirement; the zeros must be designed so that the phase shift in the plant will not cause closed-loop instability. An example is given where the shaft angle of a small motor is controlled to track a periodic reference input.

Infrared Techniques for Surveillance and Crime Deterrence

There are millions of dollars worth of optical surveillance equipment in use, nearly all of it useless after dark. To provide greater security in the dusk to dawn period, a number of infrared surveillance devices have been developed. A variety of techniques are now being employed, including pulsed and continuous-wave beams in both the direct and backscatter detection modes. The unique advantages of infrared technology relative to ultrasonics and microwaves will determine future trends in the area of surveillance and crime deterrence.

Atmospheric Turbulence in Optical Surveillance Systems

The limitations imposed by atmospheric turbulence in the design of optical surveillance systems with slant optical paths are developed. Image blurring effects which determine scene contrast ratio are separated from spot dancing effects which determine signal-to-noise ratio. The relative position of each turbulent eddy with respect to scene and observer is considered. The effects of turbulence in ground-to-ground, air-to-ground, and ground-to-air optical surveillance systems are compared.