Aerial photography is often impossible due to the presence of high clouds with contrasting shadows that do not allow to obtain materials suitable for decryption. At the same time, in a significant proportion of projects in Russia, the snowless season suitable for surveying is very short. The inability to perform aerial photography while flying below the clouds leads to cost increasing. In some cases, projects cannot be completed. Existing software does not allow to solve the problem of equalizing the brightness in the shadows for several reasons. The main reason is the inability to identify the boundaries of the shadows using only the spectral characteristics of the images, the inability to determine the amount of correction for shaded areas. To solve this problem, it is proposed to use reference images of the worse resolution obtained from the satellites. Reference images are used to localize and determine the magnitude of the spectral correction of aerial photographs. The work is performed with single orthophotographs or orthophotomosaics in the same coordinate system. To determine the boundaries of the shaded zones and the values of the corrections in brightness, methods of cartographic algebra on regular data arrays are used. Further, the obtained correction matrices are subject to filtering and are used to correct high-resolution aerial photographs. The paper gives an example of the use of free (or cheap) satellite images to eliminate or reduce the contrast of shadows on aerial photographs with a detail of 20 cm. The created prototype software allows to perform additive or multiplicative correction of an array of individual aerial photographs. The proposed approach requires more time for data processing, but gives much more acceptable results for visual (manual) decryption. The method is not recommended for use when working with images in more than 10 cm, when solving monitoring tasks with frequent repeated surveys, and also, if necessary, to carry out automated decoding using spectral standards.
Calculation of corrections to gravity measurements is one of the most important stages that determine the whole quality of research. Wrong corrections can lead to incorrect interpretation of the obtained measurements and lead to their false interpretation. To achieve highly accurate results, it is necessary to take into account not only the height, but also the entire array of information about the relief. In this case, level of detail of relief model becomes critically important, especially in case of working with rugged terrain with large number of vertically developed rock formations (outliers, rock faults, steep slopes). Now the methods normally used are based on the use of previously created materials from cartographic archives (topographic maps at a scale of 1:100,000–1:25,000). It is also possible to use open (free) terrain models. These materials have a number of drawbacks, for example, low detail of the microrelief and steep inclined surfaces (slopes, walls, faults, incisions) that have a significant effect on the values measured by gravimeters located at a small distance from such forms. The available methods do not assume ability to work with dense terrain models. These shortcomings lead to wrong corrections during gravimetric measurements. however, using of modern remote sensing methods makes possible to obtain a high-precision terrain models easily. The best opportunities are provided by lIDAR technology. here we describe differences between using lIDAR data and other types of data (1:25,000 maps, open data models), and make comparison between corrections, calculated using different data sources.
Seismic exploration is important for development of new fields and the resumption of production at old areas of oil production. These works involve studying of underground geological structures using seismic profiling and seismotomography methods. In fact, detailed information about the territory is necessary for almost every participant in the process—to find the optimal routes for movement on terrain, to optimize the volume of forest felling on profiles, for georeferencing and checking coordinate measurements at points, etc. The availability of spatial data is also important for increasing the level of safety and trouble-free operation during work. One of possible solutions is to perform field surveys using aerial photography and airborne laser scanning, followed creation of virtual models based on them with instrumentation adapted to the specifics of these works. Modern GIS, with all their development, has number of disadvantages. It is difficult to use GIS by non-specialists; full-featured GIS are expensive, and free solutions has limited analysis functionality and can’t make good 3D visualizations, it is difficult to protect spatial information from unauthorized copying. These problems can be solved without using classic GIS packages. Instead, it is proposed to use virtual environments closed from editing and access to the original data. Test area of 69 km2 in the Khanty-Mansiysk Autonomous Okrug was selected for testing virtual modeling technologies. LIDAR and aerial photography datasets were obtained, and subsequent processing of the resulting was done, forming highly-detailed virtual environment. The article discusses the main features and functionality of this model.
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