Ioannis Konstantinidis

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It is becoming increasingly important to be able to credential and identify authorized personnel at key points of entry. Such identity management systems commonly employ biometric identifiers. In this paper, we present a novel multimodal facial recognition approach that employs data from both visible spectrum and thermal infrared sensors. Data from multiple(More)
There are several natural constructions of constant amplitude zero autocorrelation (off the DC-component) waveforms. We adopt a construction for waveforms of length K, where K is a non-square-free integer. This property of K is used in the derivation of a frequency shifting (Doppler) detection algorithm which we derive. There are number theoretic properties(More)
We present a general mathematical theory for lifting frames that allows us to modify existing filters to construct new ones that form Parseval frames. We apply our theory to design nonseparable Parseval frames from separable (tensor) products of a piecewise linear spline tight frame. These new frame systems incorporate the weighted average operator, the(More)
The design of radar waveforms has received considerable attention since the 1950s. In 1953, P.M. Woodward (1953; 1953) defined the narrowband radar ambiguity function or, simply, ambiguity function. It is a device formulated to describe the effects of range and Doppler on matched filter receivers. Woodward acknowledged the influence that Shannon's(More)
In this paper, we present a novel frames-based denoising algorithm. Using a general result on lifting frames, we construct a non-separable 3D frame capable of robust edge detection. This frame detects edge information by ensemble thresholding of the filtered data. The denoising uses a hysteresis thresholding step and an affine thresholding function, which(More)
In this paper, we propose a new method to denoise a surface. This method is motivated by the Laplacian flow and the theory of tight frames. Mesh denoising is achieved by building local Wiener filtering into the detail representation of the surface. We have performed a number of experiments to assess the accuracy, advantages and limitations of our approach(More)
We produce new phase coded waveforms, by concatenating two sequences from two different families of CAZAC codes. In particular, we consider two pairs of families: Wiener and Bjorck codes, and Chu-Zadoff and P4 codes. For both pairs, equally proportioned systems generate signals with reduced sidelobes, at nonzero low Doppler shifts. The 50%-50% concatenated(More)
Constant amplitude zero autocorrelation (off the dc component) waveforms are constructed. These are called CAZAC waveforms. In the d-dimensional case they consist of N vectors, where N is given, and N is generally greater than d. The constructions are algebraic and have been implemented in user friendly software. They have the added feature that they are a(More)
CAZAC (Constant Amplitude Zero Auto-Correlation) sequences are important in waveform design because of their optimal transmission efficiency and tight time localization properties. Certain classes of CAZAC sequences have been used in radar processing for many years, while recently discovered sequences invite further study. This paper compares different(More)
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