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This research aims to investigate the color distribution of a huge sample of 613654 galaxies from the Sloan Digital Sky Survey (SDSS). Those galaxies are at a redshift of 0.001 - 0.5 and have magnitudes of g = 17 - 20. Five subsamples of galaxies at redshifts of (0.001 - 0.1), (0.1 - 0.2), (0.2 - 0.3), (0.3 - 0.4) and (0.4 - 0.5) have been extracted from the main sample. The color distributions (u-g), (g-r) and (u-r) have been produced and analysed using a Matlab code for the main sample as well as all five subsamples. Then a bimodal Gaussian fit to color distributions of data that have been carried out using minimum chi-square in Microsoft Office Excel. The results showed that the color distributions of the main sample and all subsamples are bimodal. This indicates that the color distribution is an ideal tool to differentiate between young and old galaxies. The young and blue star-forming galaxies are represented by one of the two peaks, while the old and red non-star-forming galaxies are represented by the other peaks of the color distribution. [ABSTRACT FROM AUTHOR]

In recent years, many research projects on real-time rendering have focused on the introduction of global illumination effects in order to improve the realism of a virtual scene. The main goal of these works is to find a compromise between the achievable quality of the resulting rendering and the intrinsic high computational cost of global illumination. An established approach is based on the use of Virtual Point Lights, i.e., "fictitious" light sources that are placed on surfaces in the scene. These lights simulate the contribution of light rays emitted by the light sources and bouncing on different objects. Techniques using Virtual Point Lights are often called Many-Lights techniques. In this paper, we propose an extension of a real-time Many-Lights rendering technique characterized by the integration of photometric data in the process of Virtual Point Lights distribution. We base the definition of light sources and the creation of Virtual Point Lights on the description provided in the IES standard format, created by the Illuminating Engineering Society (IES). [ABSTRACT FROM AUTHOR]

A secondary particle filter (SPF) inversion method for geostationary space object characteristics based on ground photometric data is presented. The method combines the estimation results of the standard particle filter (PF) algorithm and the resampling algorithm of the particle generation process. SPF first generates N particles according to the standard PF process, and performs the standard PF without resampling. Particle weight is an important indicator to determine the closeness of particles to the real state. With the progress of PF, the weight of particles closer to the real state will gradually increase. SPF takes the particle weight value as an important basis to judge the closeness of particles to the real state. By setting a threshold, the particles closest to the real state are screened out and roughened. The SPF method in this paper uses a particle filter twice and it is a new particle filter method. The first particle filter identifies particles near the real state. Before the second particle filter, it is equivalent to the actual state distribution of the system is known, so that the distribution of initial particles can be set more efficiently and effectively, and the number of particles close to the real state of the system can be increased. Experiment results show that the estimation error and the RMSE of the inversion error of SPF are less than PF, which not only shows that the inversion result based on SPF is better than the inversion result based on PF, but also proves the effectiveness of the inversion method based on SPF. [ABSTRACT FROM AUTHOR]

In recent years, many research projects on real-time rendering have focused on the introduction of global illumination effects in order to improve the realism of a virtual scene. The main goal of these works is to find a compromise between the achievable quality of the resulting rendering and the intrinsic high computational cost of global illumination. An established approach is based on the use of Virtual Point Lights, i.e., “fictitious” light sources that are placed on surfaces in the scene. These lights simulate the contribution of light rays emitted by the light sources and bouncing on different objects. Techniques using Virtual Point Lights are often called Many-Lights techniques. In this paper, we propose an extension of a real-time Many-Lights rendering technique characterized by the integration of photometric data in the process of Virtual Point Lights distribution. We base the definition of light sources and the creation of Virtual Point Lights on the description provided in the IES standard format, created by the Illuminating Engineering Society (IES).

Digitization of cultural assets has become an important sub-area of computer vision (CV). Thus far, the value of digitization has been emphasized in terms of asset preservation and exhibition. The third aspect of digitization value is that the obtained digital data can be used to perform archaeological analysis based on physics and optics theories and simulations. This position paper emphasizes the importance of this third aspect, using our Kyushu decorative tumuli project as an illustrative example. In particular, we focus on the photometric approaches in the third aspect and explain the equipment and methods developed there as well as archaeological findings. This paper, then, proposes to establish this area as "cyber-archaeology" through categorizing and organizing those methodologies. [ABSTRACT FROM AUTHOR]

This work aims to use the color distribution of galaxies to differentiate between blue and red galaxies. The photometric data of 300000 galaxies at redshift of z = 0 – 0.15 were collected from the Sloan Digital Sky Survey (SDSS). Three redshift ranges were considered for the purpose of this work: 100000 galaxies at z = 0-0.05, 100000 galaxies at z = 0.05-0.1 and 100000 galaxies at z = 0.1-0.15. The color distributions for all redshift ranges were determined. The results have clearly shown that the color distributions for all redshift ranges are bimodal. One of the two peaks corresponds to the blue galaxies (young and star-forming galaxies), whereas the other peak corresponds to the red galaxies (old and non-star-forming galaxies). Therefore, the color distribution of galaxies can be considered as an efficient tool to distinguish between blue and red galaxies.

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The attitude information of geostationary satellites is difficult to be obtained since they are presented in non-resolved images on the ground observation equipment in space object surveillance. In this paper, an attitude inversion method for geostationary satellite based on Unscented Particle Filter (UPF) and ground photometric data is presented. The inversion algorithm based on UPF is proposed aiming at the strong non-linear feature in the photometric data inversion for satellite attitude, which combines the advantage of Unscented Kalman Filter (UKF) and Particle Filter (PF). This update method improves the particle selection based on the idea of UKF to redesign the importance density function. Moreover, it uses the RMS-UKF to partially correct the prediction covariance matrix, which improves the applicability of the attitude inversion method in view of UKF and the particle degradation and dilution of the attitude inversion method based on PF. This paper describes the main principles and steps of algorithm in detail, correctness, accuracy, stability and applicability of the method are verified by simulation experiment and scaling experiment in the end. The results show that the proposed method can effectively solve the problem of particle degradation and depletion in the attitude inversion method on account of PF, and the problem that UKF is not suitable for the strong non-linear attitude inversion. However, the inversion accuracy is obviously superior to UKF and PF, in addition, in the case of the inversion with large attitude error that can inverse the attitude with small particles and high precision. [ABSTRACT FROM AUTHOR]

The physical properties of asteroids, such as their spin and shape, are very important for understanding the formation and evolution of the entire asteroid belt, as well as the individual asteroid itself. However, only a small part of asteroids had been determined accurately for their spin parameters and shapes due to lack of data or narrow aspect angle distribution of dataset. In the present paper, the spin parameters and convex shapes of two C-type main-belt asteroids (362) Havnia and (506) Marion are analyzed using the convex inversion method and the virtual-photometry Monte Carlo method. A pair of poles are found for (362) Havnia at ( 96 ° . 2 − 2.0 + 3.0 , + 38 ° . 8 − 2.4 + 6.8 ) and ( 273 ° . 0 − 6.5 + 1.3 , + 40 ° . 0 − 9.9 + 1.2 ) in ecliptic coordinates, the spin period values corresponding to the two poles are 16 . 918773 − 6.4 ( − 6 ) + 2.8 ( − 5 ) h (here + 2.8 ( − 5 ) represents + 2.8 × 10 − 5 ) and 16 . 918935 − 4.3 ( − 5 ) + 1.2 ( − 5 ) h, respectively. Similarly, two candidate poles are found for (506) Marion at ( 88 ° . 0 − 0.3 + 1.3 , + 22 ° . 3 − 1.5 + 1.3 ) and ( 264 ° . 5 − 0.03 + 1.2 , − 7 ° . 5 − 0.92 + 1.1 ) . The spin periods for the two poles are 13 . 549826 − 9.8 ( − 6 ) + 1.2 ( − 5 ) h and 13 . 549751 − 5.9 ( − 6 ) + 1.3 ( − 5 ) h. The shapes of Havnia for the pair of poles approximate to Maclaurin spheroids. Whereas the convex shapes of Marion for the two poles are prolate shapes, and it rotates around the longest axis. The significant divergence of weight coefficients c for Havina and Marion implies different materials on the two asteroids' surface. [ABSTRACT FROM AUTHOR]

Abstract: The central focus of the paper is to present the results of the last 2 years of the research work on development of a substitutive light source for daylight calculation of the illuminance indoors. In the paper, calculation of spatial distribution of daylight according to the new CIE standard is discussed. Another focal topic is the calculation of photometric data of a light source which substitutes vertical window or vertical window opening in computer calculations. Through the development of photometric data for a light source, so that it can be imported into calculation software, this software becomes more powerful and useful. [Copyright &y& Elsevier]