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...

We present an approach to efficiently reduce shadow map resolution while retaining high quality hard shadows. In the first step, we generate a list of sample points that are seen from the camera and then project these into light space, much like Alias-free Shadow Maps. In the next step, we analyze the list of sample points on the GPU to construct a tight light frustum for shadow rendering. Afte...

Shadow mapping is widely used in computer graphics for efficiently rendering shadows in real-time applications. Shadow maps cannot be filtered as regular textures, thus their limited resolution can cause severe shadow map discretization artifacts in the rendered images. To solve this problem, several techniques have been proposed, including variance shadow maps (VSM) and exponential shadow maps...

Shadow mapping is a very useful tool for generating shadows in many real-time rendering settings and is even used in some off-line renderers. One of the difficulties when using a shadow map is obtaining a sufficiently dense sampling on shadowed surfaces to minimize shadow aliasing. Endlessly upping the light-image resolution is not always a viable option. In this paper we describe a shadow mapp...

We present a method, based on Haines' shadow caches, for accelerating shadow ray calculations for Tay tracing processes which use spatial subdivision and surface tessellation. Trees of shadow voxel caches, containing references to both objects and voxels, are used to quickly determine whether or not a surface lies in shadow. This method does not require an additional preprocessing stage before ...

This paper presents fast and robust per-sample correct shadows for WebGL platform. The algorithm is based on silhouette shadow volumes and it rivals the standard shadow mapping performance. Our performance is usually superior when compared with high resolution shadow maps. Moreover, it does not suffer from a number of artefacts of shadow mapping and always provides per-pixel correct results. We...

  Background: COVID-19 epidemic rapidly spread all around the world with over 1500 thousand infected cases and95000 deaths. This rapid pandemic may overwhelm health care capacity and shortage of resources is a major concern.Literature provided guidelines on management of COVID-19 patients but healthcare service to the normal populationshould be continued meanwhile. Health sys...

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...

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...