requires a much larger memory for map data storage than the vector method. 

These maps are no more accurate than the paper map, but are adequate for many

applications.

13.2.2  Digital Database Maps

Digital database maps are maps presenting position data from a data base where all

the position coordinates are collected through survey ing operations.  This

information is therefore much more accurate and contains 3  D position data for

every point on the map. Variations of this type of map are now available from

various sources.  Digital maps are often combined as overlays to digitized paper

maps to provide a more accurate location of specific features such as roads,

buildings, etc.

13.2.3  HYBRID Maps

Hybrid maps are combinations of digitized paper maps and digital database maps. 

Positioning coordinates that have been collected through surveying operations are

used to  adjust  the coordinates on the paper map.  Distances between these

benchmark points can then extrapolated by the display device.  By using this

technique, the digitized paper map can provide more accurate position information

than the map it was prepared from, but it will still not provide the accuracy of a

digital database map.  The accuracy of these maps depends on the number and

accuracy of the benchmarks employed, the accuracy with which they are combined

with benchmark features on the digitized paper maps, and the accuracy of the

extrapolation algorithms.

13.3  NAVIGATION MAPS AND TACTICAL MAPS

Maps normally serve two functions on board a military vehicle: they are used for

navigation of the vehicle, and to give a visual display to the vehicle s commander of

where enemy, friendly, and neutral forces are located.  It also contains a

geographical presentation of any other information of importance to the vehicle

operators.

13.3.1  Use of Digital Maps for Navigation

Traditionally, navigation sensors (LORAN C, TRANSIT, TACAN, DECCA, optical

bearing, radar, etc.) have been used to determine position in latitude/longitude or

bearing and distance from an object.  The infor mation was then transferred to a

paper map to provide the navigator with infor mation about his actual position

relative to desired position.  This information was then used by the navigator to

decide the necessary course of action to get back to his desired track.  For many

military vehicles operating at high speed in confined waters/airspace during tactical

engagements (radio communications, weapon delivery, etc.) positioning of the

vehicle is a too time consuming process using traditional methods. Digital  database

maps with position and course/speed over the ground provided on the map by GPS

are now being employed to provide the navigator/pilot with much more time to

concentrate on other tasks without jeopardizing the vehicle s safety. GPS  derived

13 2