MAPZ and SITZ formats

The multisheet vector map of MAP format and the user maps of SIT and SITX format can be packed into one file with compression of data. The packed multisheet map has MAPZ extension, the packed user map - SITZ. To increase the compression ratio, the accuracy of the metric of objects is automatically converted to centimeters. The volume of packed data is reduced by about 3 times compared to the volume of the initial data with the maximum accuracy of the metric. One MAPZ file can contain a work region from several thousand sheets with a classifier, which simplifies the exchange and use of vector maps.

Unpacking of data is performed automatically in memory in process of reading of corresponding sheets and objects from the packed formats. If a map sheet fits in memory entirely, then it is unpacked in multithreading mode when opening the sheet data to speed up access. Packed maps are read-only. Conversion to SITZ and MAPZ format is performed in the Sorting Map task.

SITX, SITZ, MAPZ formats can be converted back to the initial SIT or MAP formats by sorting. The packed maps at inverse conversion retain the metric accuracy in centimeters.

When sorting a map in the SITZ or MAPZ format, multiscale objects, hash tables for indexed semantics, an object distribution tree and an RSС classifier are packed into the general archive with the map.