The paper presents a concept of application of the RTK-GPS technique to surveys of railway tracks. The concept was examined during an experimental survey performed over a 2 km long track section. The test survey confirmed functionality and sufficient accuracy of the RTK-GPS method as applied to railway track measurements aimed at track regulation.

The paper presents discusses a formula for the mean error m, of the refraction factor, determined basing on synchronie and bi-directional observations of vertical angles, performed for a section of trigonometric levelling. It turns out from analysis of the formula that the mean error of this factor is mostly influenced by mean errors of vertical angles and heights of distance meters and prisms over survey points. The error of a distance may be neglected; this leads to the simple working formula.

According to analyses of results of surveying measurements, description of undefined subsidence, performed with the use of S. Knothe's model is characterised by the sufficient coherence with results of measurements since the moment when the full subsiding trough becomes visible on the terrain surface. Lower coherence with results of measurements appears in the initial period after commencement of exploitation. In order to improve the quality of description within the initial phase of subsidence, a mathematical model has been developed, which is based on relations between the coefficient of the velocity of subsidence and the time co-ordinate, and from geometric co-ordinates. Obtained solutions have been verified basing on results of surveying measurements, with the use of a special computer software.

One of the basic processes in photogrammetry consists of identification and measurements of conjugate (homologous) points located within image overlapping. In analytical photogrammetry this process is solved manually by an observer. In digital photogrammetry this process is solved automatically by software and it is called image matching. This process has considerable importance for automation of orientation or aerial triangulation of photographs. The accuracy of image matching process influences the accuracy of determination of image orientation elements and computed point coordinates. This article presents the author's idea concerning matching of digital images with regard to correlation between neighbouring pixels. First, the problem of correlation between point co-ordinates will be examined in analytical photogrammetry, what will simplify considerations related to digital photo gram metry.

The problems of identification of objects have been strictly bound with sea navigation for a long time. The article presents a method of object identification by means of artificial neural networks. The classification of objects is effected on the basis of a radio signal. A comparison between classical methods and neural methods has been made. The results of research performed have been presented on real data, and a detailed analysis of the probabilistic network and its identification.

One of the major tasks in digital photogrammetry is image matching technique for finding corresponding points in a stereopair. Area-based matching has been acknowledged as being more precise than feature-based matching. Least squares multi-point matching (LSMM) is one of the Global Image Matching (GIM) which was developed from the Least-squares Single point matching (LSSM) so called area-based matching. LSMM method has been more reliable than LSSM one because the relationship between the different neighbouring points is considered in simultaneous computation. LSMM is just for the simultaneous determination of the horizontal parallaxes at the node points of the regular rectangular nets for the purpose of the establishing the DEM. This paper undertakes a trial of improving the accuracy of LSMM by consideration of the correlated pixels and terrain height differences.

Among methods of solving decision matters the technique of decision charts has been presented in this paper and the idea of their cartographic development has been proposed. The problem has been described on the base of real application that concern of choosing a place on water intake for new arisen housing estate. The technique of colour scale for visualization of choice criteria and logical operations on colour images has been proposed in order to find the place which meet earlier formulated conditions in the best way. The results has been colected in modified decision chart. Next possibilities of development of the method have been indicated

The experiment conducted with the NOKIA Multigraph 447Xpro presented in this article shows that a change of colour temperature results in a change of general colour appearance displayed on the CRT screen. However, it does not considerable affect chromatic coordinates of RGB monitor primary stimuli. The change of :a produced colour appearance which it causes can have a considerable influence on colour matching - at tłie stage of map designing on the screen. Discordances among given colour temperature set-up in lhe screen menu in relation to computed by means measurements of colour temperature are shown. Of computing and Methods of colour temperature calculating and setting are given. It has been stated which channel has a critical (decisive) influence on a colour temperature setup.

In the paper the formula for equation of the observation correction is introduced, which also includes observation terms, which are not the subjects of adjustment. The system of such type of correction equations is the basis for calculation of intermediary unknowns, which are not only the function of observations being the subjects of adjustment, but also of observations, which are not deformed by corrections. The paper presents proofs of formulae for calculation of mean errors of intermediary unknowns and functions of those unknowns for a considered case. An important general conclusion results from those proofs: both, the mean en-or of the ith unknown, and the mean error of the function of unknown, obtained from the discussed system of equations can not be smaller than the corresponding error obtained form a system, which does not include those observations. Presented formulae may be used in the case of adjustment of a connected network to higher order points, which co-ordinates are considered as observations, which are not the subjects of adjustment. Therefore we assume them as constant in a narrower range, i.e. we assume constancy of their values after adjustment; however their mean errors are considered in accuracy analysis. Derived formulae may be also used for calculation of mean errors of explicitly determinable geodetic constructions connected to known points, if the influence of mean errors of co-ordinates of those points on the mean error of a given function of unknowns is to be considered.

In this paper, the issues of today's maritime hydrography and its state are discussed. The substance of maritime hydrography and its state of development are presented. The maritime hydrography is shown and discussed from three different points of view: as the kind of maritime human activity and special maritime service; as the maritime profession and field of undergraduate and graduate education, and as the branch of science.

In this paper, there are presented the main principles of the navigational and hydrographical provision of ships' special tasks. There are specified the types of ships' tasks, but especially, ships' special tasks. There is discussed the ship's navigation process as the function of the type of the ships tasks. There is also presented the substance of the navigational and hydrographical provision of the ships' special tasks, as well as the development trends of this provision.