Kyoung-Soo Doo

Optimal keyframe selection algorithm for three-dimensional reconstruction in uncalibrated multiple images

A keyframe selection algorithm is the process of selecting the essential image for 3-D reconstruction from among many uncalibrated images. Camera autocalibration between images is also essential for 3-D reconstruction. This paper proposes a keyframe selection algorithm that selects the best image to reduce reprojection error. The camera projection matrix in the selected keyframe arises from a full camera autocalibration process. From the camera projection matrix, which is assumed exact, the algorithm calculates the fundamental matrix using algebraic derivation. By this process, false matching is eliminated and finally a 3-D data set is obtained. In our experimental results, the proposed algorithm needs less time than other algorithms; it also has fewer errors in the reconstructed 3-D data. The fundamental matrix that is gained from algebraic derivation takes less time than other algorithms, and it has same average error as the others.

Novel adaptive digital signal processing algorithm for a stationary reticle seeker

Conventional stationary reticle seeker uses an analog signal processing technology to extract a target position in the field of view. The analog technology is optimized for only frequency modulation signals, which makes it difficult to use various and adaptive signal processing, and causes the performance limit of the conventional technology. We propose a novel adaptive digital signal processing algorithm to overcome the performance limit. The proposed algorithm classifies the modulation signals into the FM and FM/AM signals and applies a different signal processing algorithm, which is optimized for the modulation characteristics of each signal. The algorithm also employs an adaptive clipping level to minimize the noise effect. Our simulation results show that the proposed algorithm is superior to the conventional one in terms of the linearity of the static gain curve, tracking performance, and robustness against noise.

Adaptive infrared counter-countermeasure for two-color spinning concentric-annular-ring reticle seeker

This paper presents a dynamic simulation loop that gives tracking results for a two-color concentric annular ring (CAR) reticle seeker. Our simulation tool includes a target flare model and a propor- tional navigation guidance loop. The CAR reticle systems performance and the flare effects are analyzed in various scenarios. When a flare is present in the field of view, the simulation results show that the reticle seeker cannot maintain precise target tracking. We propose a two-color countercountermeasure using the least-mean-square method to cope with a presence of infrared (IR) flares. The proposed method makes use of simultaneous processing of the modulation output in two IR wave- length bands. One is the midwave IR (a primary input signal), and the other is the shortwave IR (a reference input signal). Simulation results have shown that our adaptive algorithm can achieve effective cancella- tion of flare signals with high intensity.

New counter-countermeasure algorithm for two-color infrared seekers

A counter-countermeasures (CCM) algorithm in a target tracking system is required for efficient target tracking under countermeasures (CM) such as infrared flares. Most of the CCM algorithms employ some forms of spectral band discrimination to distinguish between a target and CM. We adopt two detection bands based on the spectral distribution characteristics (SDC) of a target and flares and define the energy ratio between the two band signals (MNR) to represent their SDC and to distinguish them. The proposed algorithm computes the MNR of the incident band signals and its histogram, detects the MNR of flare signal from the histogram, and extracts target signal only from the target and flare mixed signal. To estimate the performance of the proposed algorithm, we simulate it under various conditions. The simulation results show that the proposed algorithm can eliminate the effect of CM well.

Detecting digital forgeries using of a lighting direction

This paper proposes a new method for digital forensic using a technique to detect a lighting direction. We describe how the estimated the lighting direction from a segmented image and show a ratio of detecting forgery.

Simulation target detection at UV and IR bands

Air-to-Air Homing Missile has widely adopted infrared seeker, which makes use of thermal energy emitted from the target to detect it exactly. The target is equipped with countermeasure (CM) such as flare to protect itself from homing missile. The purpose of this paper is to develop counter-countermeasure (CCM) to cope with the CM operated by the target. Not only the radiant features of the target but also that of the flare at ultraviolet band have been compared and analyzed to select the band that can effectively remove the effects of the flare. We use a reference level for removal of the noise effects and the background. The simulation results show that our CCM algorithm can detect precisely the target location in spite of the presence of the flare.