Constructing an unfolding of the external surface of a Soyuz descent vehicle from digital pictures for post-flight analysis of the thermal protective coating
The paper describes a new approach to the analysis of the condition of the thermal protective coating on the descent vehicle of Soyuz manned spacecraft. A math model was developed, which makes it possible to construct an unfolding of the outer surface of a descent vehicle using as a basis a set of its digital photographs. The model is based on the principle of perspective transformations of a 3D object when constructing its projection onto a visual plane. The paper provides conditions and assumptions for the math processing of the photographs. It describes the procedure for taking pictures and constructing the unfolding. It provides examples of subsequent processing of the unfolding to obtain additional information on the state of the thermal protective coating and obtained results. It was demonstrated that the use of the said procedure significantly improves the accuracy of constructing the map of the thermal protective coating condition, and, to a considerable degree, makes it easier to perform a comparative analysis of the thermal protective coating condition on different vehicles.