Supply of photogrammetric projects with reference information obtained from large-scale aerial images

Objective. Permanent growth of the volume of remote-obtained information about location sets have challenged tasks for scientists and experts concerning quality of its processing in terms of efficiency, completeness, subject, and geometrical accuracy. The important precondition for performance of the tasks is to supply reference information for the images. The information is necessary for performance of a photogrammetric process of geometric correction of the images and for presentation of the images and geo-information products, made on their base, in the determined cartographic projection and coordinates. Analysis of current methods in photogrammetry proves substantial prospects for application of geo-referenced images for the transfer of geodesic information onto new images. In the authors’ interpretation, those geo-referenced images are called “reference images”, because they are pictures of the objects with an exactly defined geodesic position. One should not associate this notion with a reference point in its classical meaning. The main goal of the work is to develop a method to get control images of the location and transfer of the images onto aerial and satellite images. To reach the set goal the authors of the article developed a method to process an aerial image or a series of aerial images of different scales, which supply an informative source for creation of control images. It is proposed to test the developed method experimentally, supplying a block of archive aerial images with reference information. Methods and findings of the work. According to the set goal, the authors of the article made analysis of literary sources that describe innovative ways to supply reference information for aerial and satellite images. The researchers propose to use UAVs, preferably of helicopter type, to get a series of aerial images from different altitudes over the reference point. Depiction of the reference point (control image) at an image of the largest scale is appropriately distinguished by the operator or automatically, according to a pre-determined pattern image. The next step is to make a correlation search of the image of a reference point gradually onto the image of a smaller scale. Thus, there is a transfer of the position of a reference point onto a geo-referenced image. The method enables performing geodesic work on the location after the process of main aerial imagey, choosing the position of reference points according to a configuration of an actual photogrammetric block of aerial images. There is no need of clear contours on a location. Scientific novelty and practical importance. The research first gives a concrete explanation of the notion of “control image” for the tasks of geometric correction and geo-referencing of aerial and space images. The work proposes the method to get a control image from an UAV - aerial image or a series of aerial images of different scales. Effect of the method is demonstrated on the example of supplying a block of aerial images of a little-contour location with reference information. Results of approbation of the proposed method secure more efficient geodesic support for photogrammetric projects by means of refusal from physical layout of the location of an aerial image.