Depth perception in single rgb camera system using lens aperture and object size: a geometrical approach for depth estimation

In recent years, with increase in concern about public safety and security, human movements or action sequences are highly valued when dealing with suspicious and criminal activities. In order to estimate the position and orientation related to human movements, depth information is needed. This is obtained by fusing data obtained from multiple cameras at different viewpoints. In practice, whenever occlusion occurs in a surveillance environment, there may be a pixel-to-pixel correspondence between two images captured from two cameras and, as a result, depth information may not be accurate. Moreover use of more than one camera exclusively adds burden to the surveillance infrastructure. In this study, we present a mathematical model for acquiring object depth information using single camera by capturing the in focused portion of an object from a single image. When camera is in-focus, with the reference to camera lens center, for a fixed focal length for each aperture setting, the object distance is varied. For each aperture reading, for the corresponding distance, the object distance (or depth) is estimated by relating the three parameters namely lens aperture radius, object distance and object size in image plane. The results show that the distance computed from the relationship approximates actual with a standard error estimate of 2.39 to 2.54, when tested on Nikon and Cannon versions with an accuracy of 98.1% at 95% confidence level.

Investigation on Super-Resolution Focusing Performance of a TE-Polarized Nanoslit-Based Two-Dimensional Lens

Conventional optics suffer from the diffraction limit. Our recent work has predicted a nanoslit-based two-dimensional (2D) lens with transverse-electric (TE) polarized design that is capable of realizing the super-resolution focusing of light beyond the diffraction limit in the quasi-far field. Furthermore, the super-resolution capability can be kept in a high-refractive-index dielectric over a wide wavelength range from ultraviolet to visible light. Here, we systematically investigate the influence of various factors on the super-resolution focusing performance of the lens. Factors such as lens aperture, focal length and nanoslit length are considered. In particular, the influence of nanoslit length on lens focusing was ignored in the previous reports about nanoslit-based 2D lenses, since nanoslit length was assumed to be infinite. The numerical results using the finite-difference time-domain (FDTD) method demonstrate that the super-resolution focusing capability of a nanoslit-based 2D lens increases with the lens aperture and reduces with the increase of the lens focal length. On the other hand, it is notable that the length of the lens focus is not equal to but smaller than that of the nanoslits. Therefore, in order to achieve a desired focus length, a lens should be designed with longer nanoslits.

Optimization of SEM Analytical Conditions for Low K and Ultra Low K Dielectric Materials

Electron beam induced radiation damage presents great challenges for the electron microscopy analysis of low k and ultra low k dielectrics due to their beam sensitive nature. In order to minimize the radiation damage, it is necessary to understand the mechanisms behind the damage. This work presents detailed studies regarding the mechanisms behind the effects of probe currents, accelerating voltage and anticharging coating layers on the radiation damage to low/ultralow K dielectrics. The results indicate that the probe current shows a stronger dependence on the size of the condenser lens aperture than the accelerating voltage. Therefore, in terms of the probe current, the condenser lens aperture plays a decisive role in affecting the radiation damage process. In order to minimize the radiation damage, SEM imaging should be conducted with not only a low accelerating voltage but also a small condenser lens aperture to reduce probe current. Based on simulation results, the effects of a coating layer and accelerating voltage are related to the interaction volume and the penetration depth of the electron beam. Pt coating can act as not only an anti-charging layer, but also an effective barrier layer for reducing electron flux that interacts with the low/ultra-low dielectrics.