Currently performance of geodesy is characterized by a computerization and informatization. Even the simplest job cannot be done without even the small-est share of digital methods. Sometimes, however, a surveyor must make use of archival materials, including classical evidential maps. Often it turns out, that it is necessary to process such data to digital form. In the case of paper maps, matrices, and manuscript, it is not difficult. However, it requires, from the con-tractor, the knowledge of potential hazards in case of inability to perform such a procedure. Classical maps, of course, should be scan and then calibrate, i.e. to transform the system in which development is to be made. The aim of the authors, who present the issue in light of the fundamental work of surveying, is to show how difficult it is to truly prepare maps in digital format and to protect surveyingcontractor against too much confidence to the re-sults obtained without confronting them with reality.
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