REMOTE SENSING

Moscow is actively implementing modern methods and technologies for solving urban problems in all spheres of the city's life. The Remote Sensing Data Bank of Moscow (Moscow RSDB) has been created and is operated by Mosgorgeotrest.

Today in aerospace surveys of Moscow territory a comprehensive approach to obtaining, processing, storing and providing materials for use is implemented. A centralized system for providing executive authorities, city services and organizations with created by Mosgorgeotrest information resources based on aerospace photography is successfully functioning.

Mosgorgeotrest is constantly upgrading existing remote sensing data processing technologies and introducing new technologies that expand the use of remote sensing data. All working places of photogrammetric production are equipped with stereophotogrammetric stations (Fig. 1), allowing to move from creating traditional orthophotoplanes based on the materials of aerospace surveys (Fig.2) to obtaining additional data from aerial photos and satellite images, for example, to perform height measurements of buildings in stereo mode.

Fig. 1
Fig. 2

The improvement of remote sensing data processing technologies is also being implemented through the introduction of new remote sensing tools. In particular, aerial photography systems consisting of five cameras have appeared. They produce aerial photography both in the direction of the Nadir, and with an angle of 45 degrees in four directions: RCD 30 Penta (Fig. 3).

Fig. 3

The additional inclined (perspective) aerial images obtained in this way were not previously used in traditional stereophotogrammetric processing due to the presence of significant variability in scale, but they contain additional information about the objects of the area, which is almost hidden in aerial photographs by roofs of buildings and trees. In 2018, Mosgorgeotrest carried out pilot project using such an aerial survey system RCD 30 Penta on the territory of Troitsky and Novomoskovsky administrative districts. (Fig. 4).

Fig. 4

Based on the materials of a special aerial survey, in addition to the usual orthophotoplans of the area, the so-called mesh model of the area was built using an automatic method (Fig. 5).

Fig. 5

Mesh model can be used as prompt three-dimensional model of specific city territories. The special value of this model lies in the ability to observe terrain objects not only from above, but from other angles.

Monitoring the territory of Moscow using the construction of a dense height matrix (semi global matrix) was another interesting realized project. Based on the aerial survey of 2017, a dense matrix covering the heights of the entire city with a matrix step of 0.3 m was prepared. And in 2018, specialists of Mosgorgeotrest compared the data for two years by subtracting the height values. The resulting comparison model is represented as a rasterized image with color coding of the difference height and as a point cloud (Fig. 6).

Fig. 6

 

The image highlights regular shape areas of the dark blue color. They correspond to model’s depressions caused by demolishing buildings or digging trenches. Regular yellow-red sections correspond to elevations caused by the construction of new facilities. The point cloud representation of the model has the same color coding and allows you to perform detailed measurements of difference heights.

 

Another example of photogrammetric production technologies improvement is processing materials for thermal infrared survey of the territory of the city of Moscow performed from a helicopter at low altitudes of 300-350 meters (Fig. 7).

Fig. 7

Traditional software for photogrammetric processing of remote sensing data could not be used in the processing chain. Attention was drawn to the fact that the tools for creating mosaics in PhotoShop can automatically "stitch" small fragments of territory. Turning to professional software for creating mosaics, we managed to build a mosaic on the entire territory of "Old Moscow" without using operator labor.

Examples of using new software tools and improving technological processes in the field of remote sensing materials processing allow us not only to expect a significant acceleration in the processing time of materials, but also significantly expand the possibilities of using data to solve numerous urban problems, thereby attracting new consumers.