Volume 54, Nº 3 (2018)

This paper describes a problem of thematic processing of hyperspectral aerospace images. A recommended technique is based on a decoding algorithm and makes it possible to construct an effective algorithm of multiclass classification based on combining standard algorithms of binary classification of various complexity. The reason for choosing the configuration of the classification algorithm is given. Test calculations based on model and real data are used to show the effectiveness of the proposed approach to recognizing objects from hyperspectral images.

A panoramic aerial photograph composed of a series of consecutive images obtained from an unmanned aerial vehicle helps identifying visual objects more accurately. Automatic combining of aerial photographs is a complex technical problem, especially in the presence of artefacts of the recording equipment and video-recording conditions. It is assumed that a sequence of combined images is known and determined by the flight trajectory. The proposed method for combining aerial photographs is based on illumination leveling and multiband blending. The possibilities of application of SURF, FAST, FAST-ER, and KAZE point descriptors for combining images are studied. It is shown that the point descriptors on the basis of nonlinear diffuse filtering yield the best results with regard to accuracy in the presence of global and/or local visual distortions of combined images.

This paper touches upon the experience of research and development of hardware and software for air pollution monitoring of industrial cities, carried out at the Institute of Computational Modeling of the Siberian Branch of the Russian Academy of Sciences. Functional possibilities, architectural features, and user interface of the distributed web geographic information system of ecological monitoring of the city of Krasnoyarsk, which is being developed in service-oriented architecture, are discussed. Data are collected from automated posts for observing the state of atmospheric air and services of aggregation and representation of information in the form of interactive graphs and thematic maps in the web interface. An original device is developed for measuring the pollution level of the atmosphere with fine dust (PM2.5), the data from which is fed in real time to the system via a cellular network. A system is formed for integral assessment of the pollution level of the atmosphere based on Air Quality Index (AQI) calculations.

Bit space representation of measurement data is considered. A method and its associated algorithm for reversible geometric compression of measurement data frames are proposed. The algorithm is based on the conversion of a data frame into bit form with subsequent mapping onto a plane and partition into strictly homogeneous regions. Experimental results are presented showing that the proposed algorithm provides high overall compression efficiency..

The reconstruction of an image of the cross section of a thin wire obtained by an ultrasonic detector in an aqueous medium at a frequency of 1.3 MHz with a monochromatic probing signal is considered. The image was reconstructed using a synthesized aperture by correlation processing of a trajectory Doppler signal with calculated reference trajectory signals from point objects. The disturbing effect of the ultrasonic wave reflected from the surface wave generated by the moving wire on the image reconstruction is taken into account. The results of reconstruction of the image of the wire cross-section from model and experimental trajectory signals in the presence of a surface wave are given.

The contrast of a combination of two plane images spaced along the visual axis of the eye for stimulating the accommodation in 3D displays is analyzed. Two methods of normalization based on individual and group calculations of optimal coefficients of combinations for different eye pupil diameters with a specified image resolution are proposed.

A mathematical model is developed for calculating the beating noise that occurs during photodetection of a single-band optical OFDM signal. The model allows one to estimate the spectral distribution of the beating noise and the distortion of the OFDM signal subcarrier levels due to fiber dispersion. The influence of the beating noise on orthogonal subcarrier channels, possible ways of increasing the system transmission capacity, and the method of noise compensation on the receiving side are investigated.

Distortion of the spectrum of the D₁-line of ⁸⁵Rb in optical cells with an antirelaxation coating on the inner walls of the cell is studied. The spectrum shape is found to be significantly dependent on the velocity and direction of changes in the laser frequency. A physical explanation is provided for these features, which are confirmed by numerical simulations. The effect of the magnetic field on the spectrum shape is discussed.