Indian Electronic Navigational Charts (Encs) Programme: Marching Towards Self-Reliance
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Indian Electronic Navigational Charts (ENCs) Programme: Marching Towards Self-Reliance Dr. U. K. Singh and Rajesh Kumar Civil Hydrographic Officer ([email protected]) Principal Civil Hydrographic officer Indian National Hydrographic Office 107-A, Rajpur Road, Dehradun (UA), INDIA-248 001 Tel: 91-135-2747365-211 (Extn.) Fax: 91-135-2748373 ABSTRACT : Marine navigational safety is the prime concern of Hydrographic Office (HO) in order to provide safe and efficient navigation and for the development of nation maritime policies. The efforts for safe and efficient use of hydrographic products and services have paved way for development of the Electronic Navigational Charts (ENCs). The recent developments in Electronic Navigational Charts(ENCs) and Electronic Chart Display and Information System(ECDIS) are panacea in this direction. With this pertinent ambition the Electronic Navigational Charting programme of India started in 1997 with a vision to gain a greater appreciation and understanding of the use of electronic charts when operating in its Waters. More than 206 ENC’s were generated for all 6 usage bands in short span of 5 years. This paper describes vision, initial accomplishments, production flow of ENC and future vision of Indian National Hydrographic Office (INHO) in development and marketing of its Electronic Navigational Charts. The paper also described the regional cooperation in production and setting-up of RENC for North Indian Ocean Hydrographic Commission (NIOHC). 1. INTRODUCTION : Navigation of ships through nation's coastal waters and channels using improved navigational systems and new navigation technologies is the prime concern of any Hydrographic Office (HO) in the world. HOs have been haunted in past years, by shipping disasters, which have questioned the safety of life at sea, both to the mariners and ocean environmentalists. The International Marine Community is thus looking for an effective navigation technology for improved navigational safety. In recent years, HOs all over the world are playing leading role in development of Electronic Navigational Charts for marine community so that vessels can navigate safely on their voyage across oceans. Digital cartography has influenced the field of navigation in a big way with the induction of Electronic Chart Display & Information System (ECDIS). SOLAS V/19-2.4 provides the opportunity to significantly enhance safety of navigation and efficiency in maritime operation by accepting an ECDIS as meeting chart carriage requirements. The two integral parts of ECDIS are the Display System and the Electronic Navigational Chart Database (ENCDB). The ENCDB consists of navigational data accumulated through ENCs. The ENCs has paper nautical chart equivalence. The quality and contents of nautical charts is the cornerstone of safety at sea, and is strictly controlled by international agreements. Thus the industrial development of technically elegant solutions is not enough, the products must meet a well-defined standard for international approval of IMO/IHO. As a result an international standard was established by IHO which called as “S-57- IHO Transfer Standard for Digital Hydrographic Data”. In order to fully realize these enhancements to safety and efficiency, ENCs accountable from Indian National Hydrographic Office (INHO) must achieve complete coverage of uniform quality and availability through user-friendly services. INHO is responsible for the production of navigational charts and allied publications to facilitate safety of navigation in Indian Waters. And being the leading hydrographic nation in the North Indian Ocean region, INHO is committed to provide ENCs coverage in the region. With this endeavor in mind the Electronic Navigational Charting programme of India started with a vision to gain a greater appreciation and understanding of the use of electronic charts when operating in its waters for safe and efficient marine navigation. Beside this the purpose was to develop an information system in pace with technological development and demonstrate world that India is capable of producing full coverage of its National Chart Series digitally and as per the specifications laid down by IHO/IMO. 2. INITIAL ACCOMPLISHMENTS IN INDIAN ENC PROGRAMME : With a solid core of experienced cartographers and hydrographers, equipments and the nation’s most extensive holding of bathymetric and hydrographic data, a quest for development of Electronic navigational Charts started in 1997. For INHO creating Electronic Navigational Charts for its waters was a very prestigious project. Initial accomplishments include requirement of sources for generating ENCs and populating it with various authenticated data. The obvious choice for source for its creation was initially paper chart. Since Indian paper charts are in Everest spheroid, datum transformation is required to shift into WGS’84 spheroid. Calculation for spheroidal shift was based on the Least Square techniques was used from data observed from GCPs at West Coast, East Coast and Andaman & Nicobar regions of India. Although limitations of a paper chart is that if it is used for creation of ENC to enrich it, all the limitations corresponding to the scale would be transferred to ENC. But due to financial and other constraints, it was decided to digitize the paper chart information for the purpose of creating ENCs rather than going for original source material. Then came the problem of finance and after careful review, the task was contracted to an Indian firm who utilized CARISTM Suite of Software for implementing S-57 standards of IHO/IMO for generating full coverage of ENCs as per national chart series of India. The scale of a ENC is determined by the type of navigation for which it is intended, nature of the area to be covered and quantity of information to be shown. Various scale terms are used in the S-57 IHO Product Specifications Appendix B, such as Overview, General, Coastal, Approach, Harbour and Berthing, which belongs to Chart of medium-scale, large-scale, and coastal series. The IHO product specifications for ENCs although mentions navigational purpose of ENCs, but it did not specify the scale range that should be applied to each ENC. The reason behind it is that different HOs have their own scale ranges to meet the navigational purpose. The Indian Hydrographic Office followed INT M4 chart specifications for the simple reason that each ENC cell is roughly equivalent to limits as per paper chart. 3. PRODUCTION FLOW OF INDIAN ENC : INHO used Caris Editor and Caris HOM, which are two modules of Caris suite of Softwares to produce its ENCs. A conceptual model of production flow has been shown in Figure 1. Header file for chart was prepared according to the initial parameters of nautical paper chart and hence NEMR coordinate system was adopted. This coordinate system is best suited if position of features on map is based on projection. Extraction of data was made by on-screen digitization with aid of in-built INT-2 (Symbol & Abbreviation) symbols library and keeping raster chart superimposed in backdrop of the project’s header file. Digitized features are broadly classified into 3 groups viz., point, line and area. The final content of digitized features were checked with the raster content in respect of type and position of features. The map product is now transform from existing Everest spheroid to World Geodetic System’ 1984 (WGS’84) spheroid as ENC need to be prepared in this world-wide accepted spheroid as per IHO directives. This transformation required header file in LLDG type which deals the coordinate system in decimal of degree and best suited for ENC creation. A Cell of ENC is defined as an area on the surface of real earth bounded by two meridians and two parallels that means a Cell does not has projection like paper chart. In order to create a cell, cell rectangularity process was run which re-adjusts the features at the corner area of map particularly in case of large scale nautical chart at Transverse Mercator projection.. All the features of point, line and area were exclusively defined with their given specification. Meta data regarding survey reliability, navigation system, publication information and coverage of ENC are also added at this juncture of production flow. Features in the cell are spatially related to each others and hence network as well as polygon topology test run and rectify till all the features becomes topologically correct. This determines the inter-spatial relationship between objects. In order to link these features to cell’s database, keys are assigned automatically by software and thereafter features converted to Object, an intelligent feature. Assigned keys are unique code in worldwide sense so that any maritime objects won’t has common ID number in any part of world ENC database. In Object mode, a point is known as a node, a line is an arc and an area is a polygon. There are various types of data-identifiers for these Objects, which help user to filter the display of data. Ra ster Header (NEMR Extraction P of Data R O Spheroidal Shift C Chart in E WGS’84 S S Cell Creations Feature F Creations NO L Topology O W Objects NO Objects QA/QC ENC S-57 Database Validation INHO ENCs C-MAP Distribution Figure 1: Conceptual Production Flow Diagram of Indian Electronic Navigational Charts. Validation or post-production analysis of the ENC is a process to ensure a supply of high quality consistent data to end- user. As ENC is to be used in ECDIS therefore its INHO commitment to follow and ensure proper QA/QC norms as per IMO SOLAS regulations. INHO has ensured fully that all its ENCs are error free and in tuned to IHO/IMO standards. Stringent QA/QC checks were employed to final cell and subsequent updates to follow that resultant product i.e. ENCs are fully compliant as per IHO Product specifications and as a result India attained full ENC coverage of its Indian Waters as shown in Figure 2.