This paper introduces a new set of orbits, the “Repeated Shadow Track Orbits.” In these orbits, the shadow of a spacecraft on the Earth visits the same locations periodically every desired number of days. The J2 perturbation is utilized to synchronize the spacecraft shadow motion with both the Earth rotational motion and the Earth-Sun vector rotation. Motivation for the design of new shadow tra...

The automatic registration of LiDAR data and optical images, which are heterogeneous data sources, has been a major research challenge in recent years. In this paper, a novel hierarchical method is proposed in which the least amount of interaction of a skilled operator is required. Thereby, two shadow extraction schemes, one from LiDAR and the other from high-resolution satellite images, were u...

Hidden encrypted volumes can cause problems in digital investigations since they provide criminal suspects with a range of opportunities for deceptive antiforensics and a countermeasure to legislation written to force suspects to reveal decryption keys. This paper describes how hidden encrypted volumes can be detected, and their size estimated. The paper shows how multiple copies of an encrypte...

Phenomenally strong visual illusions are described in which the motion of an object's cast shadow determines the perceived 3-D trajectory of the object. Simply adjusting the motion of a shadow is sufficient to induce dramatically different apparent trajectories of the object casting the shadow. Psychophysical results obtained with the use of 3-D graphics are reported which show that: (i) the in...

Recently, several soft shadow mapping algorithms have been introduced which extract micro-occluders from a shadow map and backproject them on the light source to approximately determine light visibility. To maintain real-time frame rates, these algorithms often have to resort to coarser levels of a multi-resolution shadow map representation which can lead to visible quality degradations. In par...

A double-sided shadow minimization problem in the Boolean cube layer is investigated in this paper. The problem is to minimize the size of the union of the lower and upper shadows of a k-uniform family of subsets of [n]. It is shown that if 3 ≤ k ≤ n− 3, there is no total order such that all its initial segments have minimal double-sided shadow. Denote by ([n] k ) the family of all subsets of t...

For some computer vision tasks, the presence of shadows in images can cause problems. For example, object tracks can be lost as an object crosses over a shadow boundary. Recently, it has been shown that it is possible to remove shadows from images. Assuming that the location of the shadows are known, shadow-free images are obtained in three steps. First, the image is differentiated. Second, the...

Using data from a large, U.S. federal job training program, we investigate whether enrolment incentives that exogenously vary the ‘shadow prices’ for serving different demographic subgroups of clients influence case workers’ intake decisions. We show that case workers enroll more clients from subgroups whose shadow prices increase but select at the margin weaker-performing members from those su...

The molecular basis behind shade tolerance in plants is not fully understood. Previously, we have shown that a connection may exist between shade tolerance and dwarfism, however, the mechanism connecting these phenotypes is not well understood. In order to clarify this connection, we analyzed the transcriptome of a previously identified shade-tolerant mutant of perennial ryegrass (Lolium perenn...

Shadow segmentation is a critical issue for systems aiming at extracting, tracking or recognizing objects in a given scene. Shadows can in fact modify the shape and colour of objects and therefore affect scene analysis and interpretation systems in many applications, such as video database search and retrieval, as well as video analysis in applications such as video surveillance. We present a s...