Formation of common external border

The mode is intended for formation of the common external border for group of the selected objects on a map. It is possible to form, for example, the border of region of the Russian Federation by the marked administrative areas included into it.

The similar result can be achieved by a merge of the selected areas, however a merge - noticeably lengthy process. Various can be and the result. As a result of an execution of a merge the all subobjects which are available to the initial objects are saved. The common border - only an external contour. Besides, some restrictions and on input data are imposed.

In particular, to obtain the expected result it is necessary, that a line forming an external contour, was "free". Ie at each of the "boundary" objects, a site involved in the formation of a common external contour should not have a match with the site of another selected object. For example, the error situation arises in case of "clones" at boundary object.

Besides, boundary objects should be topologically coordinated. Points - borders of a fragment of an external contour of each of boundary objects should have reciprocal points on the neighboring boundary objects.

For execution of process it is necessary to mark group of united objects on a map, to make active a mode, to select (to make a choice) one of boundary objects and to specify type of object for creation of an external contour (linear or polygon).

After an execution of process it is necessary to make the analysis. In case if the marked objects are united not all, it is necessary to analyse a situation in a point of "cut" of a contour, to undo operation (or to delete wrongly constructed contour), to correct an error and to retry operation.