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The square and rectangular shape of the pixels in the digital images for sensing and display purposes introduces several inaccuracies in the representation of digital images. The major disadvantage of square pixel shapes is the inability to accurately capture and display the details in the objects having variable orientations to edges, shapes and regions. This effect can be observed by the inaccurate...
Autonomous UAVs need on-board vision system to be able to navigate, avoid collisions, and execute missions. Small UAVs can carry small form factor vision system with low power consumption due to natural payload limitations. Therefore it is a natural idea to use cellular sensor-processor arrays to implement the necessary vision functions. In this paper, we present a UAV collision warning algorithm...
The array output for a distributed source can be approximated by the superposition of the array response to a large number of closely spaced point sources. In the limit, a distributed source corresponds to an infinite number of point sources. In this approximation, the number of free parameters increases with the number of point sources. In this paper, we show that if the point sources (approximation...
An important part of the filtered backprojection (FBP) algorithm is the ramp filter. This paper derives the discrete version of the ramp filter in the Fourier domain and studies the windowing effects. When a window function is used to control the noise, the image amplitude will be affected and reduced. A simple remedy is proposed to improve the image accuracy when a window function must be used.
Compressive sensing (CS) has successfully been applied to reconstruct sparse signals and images from few observations. For multi-component nonstationary signals characterized by instantaneous frequency laws, the sparsity exhibits itself in the time-frequency domain as well as the ambiguity domain. In this paper, we examine CS in the context of nonstationary array processing. We show that the spatial...
We revisit the topics of near-field adaptive beamforming and source localization following an alternative approach based on a spatio-temporal spectral representation of the acoustic wave field. With the proposed method, the wave field is expressed as a separable combination of the signal and spatial components that characterize the various sources in the acoustic scene. This allows beamforming operations...
In this paper we propose a qualitative representation for 3D algorithms that given a numeric discrete sampling of a function, produce a qualitative version of it, expressed in the proposed representation. The data may present noisy due to errors, numerical imprecision, etc. We start filtering the information, then we segment the information into monotonic regions. Finally a landmark refinement is...
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