Data Sorting / compression

After any changes made on coordinates or semantics information    corresponded   to  map objects (editing, updating, control, data editing and also resource editing if  mapping order for objects in digital map was changed), it is recommended to start data sorting procedure to speed up further processing.  This procedure also causes data compression.

Sorting of map objects can change precision of data storage.

For a correct execution on a map of various topological and overlay operations (construction of a network, zones, crossings and unitings, etc.) it is recommended to create maps with the maximal precision of coordinates. The user maps always have the increased precision of coordinates.

For correct formation of ground-management documentation, calculation of lengths, squares, the list of coordinates, etc. it is recommended to set in addition the precision of storage in millimeters or centimeters. It will provide uniformity of results of calculation in all tasks (Geodetic editor, Map Editor, Map Computer, etc.) without additional setting up parameters.

If at sorting the precision of coordinates is set in millimeters or centimeters the number of version of map data format varies (at the user maps - does not vary). Such maps can be opened only by versions of programs 9.15.3 and newer.

For return to the previous version of map format it is enough repeatedly to sort a map, having exposed precision of coordinates - microns (maximum). SXF format is the common format for all versions of maps format.

If Sorting updated sheets only mode is switched on then sorting will be carried out only for those sheets on which objects were edited. It reduces time of sorting.

If Delete copy edited objects mode is switched on then after sorting it is impossible to restore the objects deleted or edited earlier. Thus the volume of data on a disk decreases.

If Coordinate hight precision mode is switched on, coordinates of all objects will be transformed to a format of double precision and all new objects will be in this format. It is necessary, for example, for cadastral maps with increased requirements to precision of calculation of the areas, overlay operations, etc. Thus the volume of a file of coordinates will be twice more of usual. The user maps are created only in a format of double precision irrespective of a sorting mode.

If Normal coordinates precision mode is switched on, all coordinates will be led to one format. It is important for a correct execution of overlay operations and editing of common points. Format of coordinates can become a miscellaneous after execution of operations of carry of objects from other maps, update from SXF, cuttings of group of objects, etc.

Thus precision of storage of coordinates for maps of scale 1 : 200 000 will be not worse than several decimeters (value in dialog is overestimated), and precision of source data for creation of such maps is not better than 10 meters.