Processing of square hydrography objects (rivers)

Square objects are converted to linear objects in accordance with the table of recoding. The table of recoding is contained in the file with the IHS extension. Processing of each areal object of hydrography consists of the following stages:

- search of linear objects (such as Inflows) adjoining to the processed square object;

- replacement of sections of square objects by sections of linear objects;

- dragging objects such as Inflows to the metrics of the received linear objects.

Dialog contains a field of a choosing a key of the square object,  table of recoding (the table of conformity of ranges of replaced sections of the square object to keys of linear objects), the list of keys of objects of type the Inflows and fields of editing:

- minimal width of object;

- tolerance of coordination of inflows.

In the beginning of execution of the task the copy of the source map is automatically saved into a SXF-file with addition to the name of sequence number of a current stage.

Replacement of sections of square objects onto linear objects is performed taking into account the maximum width (in meters on the terrain) of the section being replaced. If the length of the section is less than 3 millimeters, the  sections is not replaced. If there are distances between the parts of the same river that are replaced, less than 3 millimeters, the parts to be replaced are combined. The key of object and corresponding semantics «Width by scale» are set according to the width range. The width range is determined by the maximum width of the replaced section.

At replacement of the square section of the rivers by linear objects, the existing spatial topological links with objects corresponding to the list of coordinated objects are taken into account.The analysis of quality of the output map is carried out on the basis of the error log (messages) received upon termination of process of generalization of hydrography objects, in the dialog the Map Editor / View error. Dialog of the protocol includes a list consisting of created linear and square rivers and of deleted square rivers. For viewing deleted objects the mode to Show deleted objects should be enabled. When moving through the list, you can analyze the results of the performed generalization process, as well as determine for line objects the need for uniting with existing linear rivers and the need to replace semantics. Semantics of ununited map objects can be edited in the Select Object dialog. Uniting of linear objects of hydrography is carried out in an interactive mode the Map Editor / Paste & Cut / Merge objects. The generalization of hydrography provides for automatic preservation of topological links for objects that have undergone generalization and objects associated with them. The result is not unambiguous and requires mandatory verification at the ends of the interfaces. The operator needs to select a reference point (object) for reconciliation in order to obtain the most evident image of the map. The coordination of points is carried out at viewing results of generalisation in the interactive mode of Map Editor / Topology / Snap 2 vertex.

Automatic replacement of sections of square objects having width of less than the permissible size for maps of output scale, by sections of linear objects increases accuracy and speed of their drawing in comparison with a manual method. Taking into account the available spatial topological links with objects significantly reduces the time spent onto topological matching by a manual method.