The paper presents the methodology for developing passability maps that may be used for planning the movement of unmanned ground vehicles (UGVs). They were based on a standardised spatial data base in the scale of 1:25 000, created and used by the military forces and a high resolution digital terrain model. Maps were generated for square shaped primary fields. 5 sizes of such fields were used (side length 25, 50, 100, 200 and 500 m). Basing on the ground cover and terrain formation, for each primary field the index of passability (IOP) is calculated, being the terrain resistance coefficient. The obtained maps were compared to each other. As the presented methodology is completely automated, an analysis of the passability maps generation time depending on the size of the primary field was conducted. The obtained results demonstrated that maps that are most useful for planning UGV routes are those generated with use of the smallest primary fields (25 m), as they visualise the most terrain obstacles. The generated maps may be recorded in the UGV memory. As far as completely autonomous structures are concerned, this will enable the algorithms implemented in the vehicle, with the support of other sensors, to determine the optimal route of the UGV.