Том 43, № 4 (2017)

The paper considers a problem of multiple person tracking. We present the algorithm to automatic people tracking on surveillance videos recorded by static cameras. Proposed algorithm is an extension of approach based on tracking-by-detection of people heads and data association using Markov chain Monte Carlo (MCMC). Short track fragments (tracklets) are built by local tracking of people heads. Tracklet postprocessing and accurate results interpolation were shown to reduce number of false positives. We use position deviations of tracklets and revised entry/exit points factor to separate pedestrians from false positives. The paper presents a new method to estimate body position, that increases precision of tracker. Finally, we switched HOG-based detector to cascade one. Our evaluation shows proposed modifications significantly increase tracking quality.

An approach is proposed to the height and displacement maps normalization from the spectra described by J. Tessendorf. Techniques are considered to avoid some rendering artefacts with projected grids when the viewer is (1) far from the origin of a coordinate system and (2) near the waterline. Modeling and lighting of the water surface is described. Techniques based on volumetric models using screen-space raytracing for rendering various atmospheric effects (clouds, fog, rain, snow, etc.) are proposed. Approaches to implementing these techniques applicable to a wide range of real-time applications are described.

The visualization of stereo images obtained from two eyepiece cameras of a stereo microscope with different exposures is studied. This problem is solved to improve the quality of resulting images in the case when one image is not sufficient for capturing an object with the desired color reproduction accuracy and high level of detail both in dark and light regions. An approach to solving this problem in which differently exposed images are split between two views is considered. This approach allows us to significantly reduce the capturing time and to enhance the quality of capturing moving objects. The algorithm described in [1] is used as the basic algorithm; the main steps of this algorithm are the stereo matching of two input images and the construction of high dynamic range images. Modifications of the basic algorithm that use different stereo matching techniques are proposed. The application of the algorithm described in [2] for the visualization of stereo images without constructing high dynamic range images is discussed. A database of images captured with different exposures by a stereo microscope is created. The quality of algorithms applied to the images from this database is evaluated in the HDR-VDP-2.2 metric [3].

This paper considers various aspects of static analysis of C# programs in order to detect the maximum number of software bugs in an acceptable time. A complete cycle of software static analysis is described with the main focus being placed on the specifics of the C# language. Some methods are discussed that take into account popular features of C# at all levels of analysis: call graph and control flow graph construction, dataflow analysis, as well as context- and path-sensitive interprocedural analysis. A symbolic execution method is proposed, which is based on the works devoted to the Bounded Model Checking (BMC) and the Saturn Software Analysis Project. A memory model is described that enables an accurate intraprocedural analysis and allows one to create compact representations of error conditions associated with functions, which are essential for interprocedural analysis. A special attention is paid to the optimizations that occur during path-sensitive analysis of error conditions. The conditions need to be optimized in terms of size, because path-sensitive interprocedural analysis requires saving a large number of conditions for each analyzed function. The conditions are resolved using advanced SMT solvers (such as the Microsoft Z3 Prover). This paper also considers various approaches to modeling the behavior of library functions: based on a summary containing a set of properties required for analysis, or based on simplified implementations in C#. All the discussed solutions are implemented in the SharpChecker static analysis tool and are tested on a number of open-source projects from 1.5 thousand to 1.35 million lines of code.