The work aims to analyze and study the possibilities of using “Cetus” unmanned aerial vehicle (UAV) for performing topographic aerial surveys. The authors developed and tested aircraft-type UAV for topographic aerial photography. The studies were conducted on a specialized landfill, at which there is an appropriate number of situational points whose coordinates are determined with high accuracy. These points were used as both reference and control points. The obtained UAV aerial survey materials were subjected to a phototriangulation process to determine the orientation elements and to analyze, first and foremost, the angular orientation elements. The surveying was carried out on a mountainous territory, where the spatial coordinates of 37 situational points were determined by the method of ground-based GPS survey with an average accuracy of up to 0.05 m. These points were used as reference and control points. Aerial photography was performed in such a way that the scale of the images was as uniform as possible. The design solutions implemented in the Cetus UAV provide all the possibilities to perform aerial surveys of territories in strict compliance with the projected flight parameters. UAV equipment provides the necessary real-time correction of the position of the aerial camera. At the same time the optimum straightness of routes, stability of scales and mutual overlapping of pictures is reached. Regarding the accuracy of obtaining the spatial coordinates of the points of terrain objects, using “Cetus” UAV surveys, plans can even be made on a scale of even 1: 1000. As a result of the creation of the UAV “Cetus”, it became possible to perform the topographic aerial survey of the territories and to create large-scale orthophotos that fully meet the instructions. As a result of testing the “Cetus” UAV, it can be used in production processes when drawing up topographic plans for a large-scale series: 1: 1000 – 1: 5000, which will significantly save the cost of performing topographic work.

This work describes original methods of improving the quality of Digital Elevation Models (DEM), obtained by means of satellite altimetry data. Shown are subsequent steps of geometric correction of global raster DEM, such as SRTM, SRTM DLR and ASTER GDEM, which are commonly available. According to the authors of this analysis, methods proposed here can be used in geoinformation projects.

Aim. To develop and accomplish an experimental testing of the method of creating a mask map of high-level terrain objects. Methodology. On the basis of the cross-correlation method, it is proposed to carry out the estimation of the similarity of orthophotos that have a mutual spatial overlap. The comparison of the left and right images takesplace in pixels, for pixels with the same spatial coordinates X and Y, and therefore, there is no need to organize the movement of the search bar and to search for the corresponding points as such. It also removes the limit on the size of the image-the standard. In addition, the relatively small cross-correlation sensitivity to the differences in the illumination of the scene is very important for the choice of the correlation coefficient as a measure for the comparison of images. Taking into consideration the perspective deformations of images of high-level terrain objects it is expected that the number of pixels with negative comparison is significantly higher for regions with images of such objects. The overall picture throughout the study is a map-mask of high-level terrain objects. Such a map can be formed with the help of geoinformation modeling of polygonal objects, which outline zones with a high compaction of pixels with a negative comparison result. Results. The considered method of creating a map-mask of high-level terrain objects provides a possibility of obtaining important information about the quality of the digital topographic surface model used for orthotransformation of aerial photographs. The revealed effect of compaction points with a negative result of the mutual comparison of orthogonal images by the cross-correlation method allows to identify and establish the spatial location of high-level terrain objects such as roofs of buildings, fences, power lines, crowns of trees, and shrubs. Practical meaning. An example of map-mask application of high-level terrain objects for orthoimage stitching is given.

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