Processing of relief heights matrix (DEM)

At the given stage control of DEM, smoothing of DEM and prompting of analytical structure, coordination of DEM with high-altitude points and coordination of DEM with hydrography is carried out. For execution of concrete process it is necessary to establish a corresponding flag.

ATTENTION! All processes on coordination of DEM change values of heights in a matrix. For an opportunity of data restoration it is recommended to save initial DEM under other name.

During control of DEM the conformity check of nodes heights of DEM to passport values and the control of heights change of the neighbouring nodes over step of DEM is carried out. As a result of the control defective heights are replaced onto heights interpolated by the neighbouring nodes, and passport data are replaced onto really defined one.

Smoothing of DEM by the lines and columns is the process, which can improve forms of a relief by elimination of mistakes of profiling on the photogrammetric device, in particular "tightening" of profiles. This process can change essentially the information, therefore it is allowed to use smoothing of DEM only to the experienced users perfectly representing what results should be received.

Prompting of analytical structure consists in forming more smooth surface of a relief by a method of the dispersive analysis. The program calculates factor of a dispersion on a local site which center is the current node of a matrix and enters the amendment into the value of height according to the received factor. The size and accordingly a degree of updating are controlled in parameters.

Coordination of DEM with high-altitude points is necessary for exact "stacking"  of horizontals in area of a high-altitude point.

For coordination of DEM with hydrography and exact "stacking" of contours in region of location or passage of hydrography are applied the coordination with linear water-currents and area surfaces.

At coordination of hydrography with DEM the user should fill filter on hydrography, independently having established necessary layers, for example: (hydrography), type (line) and objects which will be coordinated with DEM (here can enter the rivers, channels, passages, dry channels, ravines and other objects connected with a water-current).

During coordination of DEM with hydrography there is a sorting of the metrics of hydrography by length and quantity of metric points. Sorting is necessary that more lengthy objects, (for example, the rivers), had a priority at coordination of DEM before less lengthy (for example, streams, gullies), and DEM, coordinated with more lengthy objects, would be used as the initial information for the coordination with less lengthy one. DEM is coordinated by a strip overlapping the hydrography onto step of DEM.

Other variant of the coordination of a matrix with hydrography is use of objects with the three-dimensional metrics. In this case the user independently should check monotony of decrease of Н coordinate from a source to a mouth.

Thus, preliminary processing DEM raises quality and precision of the entrance information for forming contours.