Search

This paper addresses the problem of identifying and tracking moving objects in a video sequence having a time-varying background. This is a fundamental task in many computer vision applications, though a very challenging one because of turbulence that causes blurring and spatiotemporal movements of the background images. Our proposed approach involves two major steps. First, a moving object detection algorithm that deals with the detection of real motions by separating the turbulence-induced motions using a two-level thresholding technique is used. In the second step, a feature-based generalized regression neural network is applied to track the detected objects throughout the frames in the video sequence. The proposed approach uses the centroid and area features of the moving objects and creates the reference regions instantly by selecting the objects within a circle. Simulation experiments are carried out on several turbulence-degraded video sequences and comparisons with an earlier method confirms that ...

Ribs appeared cryptically in the Middle Jurassic nautiloid Paracenoceras. These ribs were produced by crowding of growth lirae as a corollary of change in body size during paedomorphic evolution. Initially, they had no direct functional significance. Some other contemporary genera are found to have similar ribbing patterns, partially developed on either the flanks or venter of the adult body chamber. Subsequently in nautiloid phylogeny, ribs spread all around the whorl, becoming analogous to those of contemporary ammonites. Shell rugosity is observed to occur with increasing frequency in post‐Triassic nautiloids, paralleling the trend in ammonites. This is believed to be an outcome of the ‘arms race’ known as the Mesozoic marine revolution. Ribbing that was not at first adaptive in these nautiloids was subsequently co‐opted as a defensive adaptation. The evolution of this structure is a good example of exaptation.