In this paper, we propose a new method for passive depth estimation based on the combination of a camera with longitudinal chromatic aberration and an original depth from defocus (DFD) algorithm. Indeed a chromatic lens, combined with an RGB sensor, produces three images with spectrally variable in-focus planes, which eases the task of depth extraction with DFD. We first propose an original DFD algorithm dedicated to color images having spectrally varying defocus blurs. Then we describe the design of a prototype chromatic camera so as to evaluate experimentally the effectiveness of the proposed approach for depth estimation. We provide comparisons with results of an active ranging sensor and real indoor/outdoor scene reconstructions.
We propose to add an optical component in front of a conventional camera to improve depth estimation performance of depth from defocus (DFD), an approach based on the relation between defocus blur and depth. The add-on overcomes ambiguity and the dead zone, which are the fundamental limitations of DFD with a conventional camera, by adding an optical aberration to the whole system that makes the blur unambiguous and measurable for each depth. We look into two optical components: the first one adds astigmatism and the other one chromatic aberration. In both cases, we present the principle of the add-on and experimental validations on real prototypes.
A general method is developed which permits the minimization of the energy of an excited singlet or triplet state. The conditions for energy minimization are obtained without introduction of Lagrange multipliers by a highly concise matrix formulation. The method is applicable to excited states expressed as linear combinations of an unlimited number of singly excited configurations. The method reduces to an iterative system of matrix diagonalizations and is thus equivalent to a pseudoeigenvalue problem. Calculations for the lowest n→π* and π→π* states of thiazole and 2-methylthioimidazole are reported.
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