DSM PPT.pptx

Dsm

1. Defense Series Map

2. G eneral 1. As part of National Map Policy (NMP 2005), two series of maps are being published by Survey of India, which are meant to replace the existing Everest Series Maps. Maps being published as part of NMP 2005 are: (a) Open Series Maps (OSM). (b) Defence Series Maps (DSM). 2. The Open Series Maps (OSM) are devoid of the military grid, VAs/VPs and height/contour data (in restricted areas). These are meant for civil agencies and are available for purchase, commercially. The Defence Series Maps (DSM) are meant for exclusive use by Defence and Para Military Forces. These maps contain all topographic information, and are classified as restricted and above. 3. The contents and accuracy of Everest Series Maps (currently in use) and that of Defence Series Maps are the same. The DSMs are currently being prepared by mathematical transformation (determined empirically) from Everest Series Maps. 4. However there are certain changes in DSMs with respect to the Everest Series Maps. These are explained in the succeeding paras . Major Changes 5. Layout . The layout of Everest Series and Defence Series Maps are different. The layouts are shown at Sketch P & Q respectively.

3. 6. Everest Series Map Numbering . The map sheet numbering in Everest Series is from 1 to 106. There are no numberings for areas in sea, i.e. areas devoid of land mass . Also, the numbers do not follow any standard pattern and so, it is cumbersome to use them on computer applications. The Everest Series numbering for India is explained below:-

4. (a ) Value of each main number, from 1 to 106 (39 to 88 for India) is assigned to a 4 x 4 tile. In Figure 1 , refer tile number 55. This tile is of size 4 x 4 and is divided into 16 equal tiles of 1 x 1 and each tile is assigned an alphabet from ‘A’ to ‘P’. Each of these 1 x 1 tiles form a 1:250K scale map (also refer Figure 2 ). A E I M B F J N C G K O D H L P

5. ( b) Each of the 1 x 1 tile(refer Figure3 )is further divided into 16 equal tiles of15 ’ x15 ’ each , and are numbered from 1 to 16 (refer Figure 3 ). Each of these 15’ x 15’ forms a 1:50K scale map. Every 1:250K map therefore contains 16 x 1:50K maps. 1 5 9 13 2 6 10 14 3 7 11 15 4 8 12 16

6. (c) Each of the 15’ x 15’ tile (refer Figure 4 ) is again further sub divided into 4 tiles of 7.5’ x 7.5’. These 7.5’ x 7.5’ tiles represent 1:25K scale maps (refer Figure 4 ). Therefore, every 1:50K map can be divided into 4 x 1:25K maps. NW NE SW SE

7. 7. DSM Numbering . The DSMs on the other hand, follow an international system of numbering, which can be extended to any part the world. The DSM numberings are different from Everest Series Maps. However, for ease of reference, all DSMs are printed with equivalent Everest Series Map number also . For map numbering in DSMs, the world has been divided into tiles of 6 x 4 (refer Figure 5 ). Each tile is assigned a numeral for every 6 of longitude and an alphabet for every 4 of latitude. The numerals in longitudinal direction (west to east) begin from 1 at 180 west longitude and extend up to 60 at 180 east longitude. In the latitudinal direction, every 4 of latitude is assigned an alphabet starting from ‘A’ at the equator and alphabets increment towards the poles. On both the hemispheres (north & south of equator), the same pattern is followed . This method of map numbering is much simpler and logical. Using this method, the numbering system can be extended to any part of the world; which has been an inherent drawback in Everest Series Maps . 9. The numbering system in DSMs for India and adjacent countries is explained in succeeding paras , with respect to equivalent Everest Series numbering.

8. (a) As explained in Para 7 above, each 6 x 4 tile is assigned a numeral and an alphabet in the longitudinal and latitudinal direction, respectively. For the purpose of elaboration, tile F44, highlighted by the shaded box in Figure 5 is being used in the succeeding paras to explain the numbering system.

9. (b) The tile of 6 x4 falling between longitude and latitude as shown in Figure 6 is assigned values F & 44, as per DSM numbering convention explained at Para 7 above . So this tile is assigned the main value F44. This 6 x 4 tile is divided into 24 equal tiles of 1 x 1 and each tile is assigned an alphabet, starting from ‘A’ to ‘X’ (refer Figure7 ). Each of these 1 x 1 tiles form a 1:250K scale map. A B C D E F G H I J K L M N O P Q R S T U V W X 78 84 24 20 6 4

10. ( c) Each of the1 x1 tile shown at Figure 7 are further divided into 16 equal tiles of 15’ x 15’ each, and are numbered from 1 to 16 (refer Figure 8 ). Each of these form a 1:50K scale map. Every 1:250K map therefore, contains 16x1:50Kmaps .   1 5 9 13 2 6 10 14 3 7 11 15 4 8 12 16 F44H13 (1:50K scale map) Note . F44H13 in DSM is equivalent to 55 N/13 on Everest Series

11. (d) Each of the 15’ x 15’ tile is also further sub divided into 4 tiles of 7.5’ x 7.5’ (refer Figure 9 ). Each of these 7.5’ x 7.5 ’ tiles represent a 1:25K map. Therefore, every 1:50K map can be divided into 4 x 1:25K maps. F44H13/ NE (1:25K scale map) Note . F44H13/ NE in DSM is equivalent to 55 N/13/ NE on Everest Series

12. Symbology . There are very few changes in symbology of DSMs with respect to Everest Series Maps. Few new symbols have been added and few have been modified. The modifications of the symbols have been carried out to make them self explanatory and more user friendly. Unlike the Everest Series, most of the important symbols have been displayed on the left margin of all DSM maps with description . All changes in symbology are shown at Appx A.

13. Military Grid Reference System . A rectangular grid coordinate system is required, as computation of bearing, grid coordinates (in northing & easting) and length can be easily determined and a unique, brief yet precise reference can be made. The DSM grid zones (refer Figure 11 ) are of size 6 x 8 and all zones are of same size, unlike the Everest Series ( India & Adjacent Countries Grid System ) shown at Figure 10 .

14. Figure 10 GRID ZONES OF EVEREST SERIES MAPS

15. Projection & Datum The map projection and datum of DSMs and Everest Series maps are different. The DSMs are based on a global datum on which positioning systems like GPS are based. On the other hand, the Everest Series Maps are based on a local datum, only suitable for the India & adjacent countries . Details of the projection & datum are given below:-   Map Series Primary Projection Secondary Projection (Military Grid)   Datum   Everest Series   Polyconic Lambert Conformal Conical (LCC)   Everest Defence Series Lambert Conformal Conical (LCC)   Modified LCC   WGS-84

16. Figure 11   GRID ZONES OF DEFENCE SERIES MAPS

17. GR Values The GR (grid reference) of a point in DSM and its corresponding Everest Series Map will be different. This is because of the change of datum & projection as mentioned in Para 11 above. However, the geographical location of all points will remain the same.

18. Grid Letterings . Everest Series Maps . Any 6 figure GR derived from a map would repeat in the same grid zone after every 100 km. To overcome this problem, all 6 figure GRs are prefixed by two letters (alphabets), which make them unique in that grid zone. These letters are printed in the body of maps in bold fonts. It is also likely that GRs prefixed with grid letters may repeat in different grid zones. Again, to counter this, the GR values already prefixed by grid letterings are again prefixed by the grid zone name.An e.g . is shown in Figures 14 & 15 .

19. Defence Series Maps . The grid letterings ( as explained in Para 14(a ) for DSMs have been designed in a very simple way, unlike the Everest Series. The grid letters have been designed keeping in mind Digital environment. Details are explained in succeeding paras . (i) Each DSM grid zone (refer Figure 11 ) is overlaid with a military grid of size 1000,000 m x 1000,000 m for preparing the military grid. These overlays are further sub-divided to squares of 100,000 m x 100,000 m each (refer Figure 16 ). These squares are numbered serially from ‘A’ to ‘K’ in both northing & easting direction, excluding alphabet ‘I’.

20. Figure 16 MILITARY GRID OVERLAY ON DSM GRID ZONES  

21. (ii) Any DSM map sheet falling in any of these100,000 m x 100,000 m sized squares (refer Figure 13 ) will be assigned grid letters as per its geographic location on the grid zone. A portion of DSM map sheet No H44O9 (62C9) is shown in the Figure 17 . From the full values of northing & easting , it can be ascertained that this map falls in the grid square denoted by values (refer Figures 17 , 18 & 19 ).

22. (iii) The GR values of any point falling on this map sheet (H44O9) therefore would be prefixed by DSM grid zone 6F & grid letter FJ. An eg is given vide Figures 20 & 21 .

23. GR Conversion . For the ease of GR (grid reference)conversion between Everest & Defence Series Maps, a software utility has been developed by ADG Military Survey (GSGS). This utility is called ‘ GeoCalc ’, and can be installed on any computer for converting GRs from Everest to Defence Series and vice versa. This software is meant strictly for tri-services and can be obtained from ADG Military Survey (GSGS). Methodology of using GeoCalc is described at Appx B.

24. For any further clarification on any issue related to technical aspects of DSMs, ADG Military Survey (GSGS) be approached.

25. ANY QUESTION?

26. THANK YOU