What is wrong with the S-100?

In open publications on the implementation of new hydrographic standards based on S-100, it is difficult to find rational criticism, which makes the practical implementation process expensive and complicated. Assessing their advantages and disadvantages is nearly impossible due to the lack of a clearly formulated problem, with most arguments appearing declarative and lacking evidence.

The purpose of this article is to examine the main shortcomings of implementing S-100 in navigational and hydrographic practice and to propose solutions aimed at overcoming them.

The primary argument in favor of implementing new hydrographic standards based on the universal S-100 model is the potential for data interoperability. However, it is difficult to find a clear explanation of what the problem with spatial data interoperability actually is and how exactly S-100 solves it.

The IHO (International Hydrographic Organization) prohibits the use of data produced in the S100 model—such as information on surface currents (S-111), sea level data (S-104), precise bathymetry (S-102), and port infrastructure details (S-131), among others—together with data in other formats, specifically S-57 ENCs. This restriction compromises the main argument of the proposed model's universality. Information prepared in the aforementioned formats can only be used with S-101 ENCs, which means that S-100 is "universal" only within its own framework, much like any other linguistic system.

The problem with implementing new hydrographic standards based on the S100 lies in the obvious contradiction between the declared advantages of the universal model and the policy of its practical implementation.

Knowledge Base

Electronic Navigational Charts (ENCs) in the S-101 format do not differ fundamentally from those in the S-57 format, except that the global collection of charts in S-57 has already been created and is functioning successfully. It took several decades for the International Hydrographic Community to develop this collection, requiring significant investments, including the development of technology, quality control systems for the charts and their updates, training personnel, and so on.

Knowledge Base

The issue of implementing hydrographic standards based on the S-100 model can be practically addressed in two ways:

• Either simply allow the combined use of S-57 and S-100, as there are no technical restrictions preventing this.

• Or extend the universal S-100 model to include ENCs produced in the S-57 format. This would ensure an evolutionary transition from S-57 to S-101 and allow the use of both types of charts within the unified S-100 model.

We refer to the second option as "S-157," which offers a highly rational approach to practical implementation. It is clear that the value of the information itself is higher compared to the format in which it is transmitted—semantics take precedence over syntax. Therefore, it is prudent to direct limited resources primarily towards creating new data that navigators have long needed, such as detailed bathymetry, currents, weather, etc., rather than reworking what already exists and functions—S-57 ENC Global Portfolio.

This approach appears more appropriate as it ensures the combined use of data in S-57 and information published according to S-100 requirements. It does not negate the S-101 format but makes the transition to it less costly and more evolutionary.

The core idea behind S-157 is to present S-57 data in an S-100-compatible format. This approach stays within the boundaries of the overall data model and allows for the joint use of information without the need for conversion or modification. Instead, the data is simply described—or encapsulated—using S-100 methods.

This solution significantly reduces the costs associated with transitioning from S-57 to S-101 and enables the combined use of these formats within a single model. It simplifies the development of new ECDIS systems, which would no longer need to support two different standards. Instead, they would only need to work with the universal S-100 model, a requirement already necessary for interoperability with the entire family of new standards.

Encapsulating the global collection of S-57 charts could be done as soon as tomorrow, as this is a purely formal procedure that doesn't entail significant costs. Software tools for this encapsulation could be provided free of charge to all Hydrographic Offices, ECDIS manufacturers, and ENC distributors.

Thanks to S-157, users would quickly gain access to official ENCs described in accordance with S-100, allowing them to use these charts alongside other information prepared within the universal S-100 model—such as S-102 bathymetric data, S-111 current data, S-131 port infrastructure information, and more. This would eliminate the need to wait for the official release of S-101 charts and overcome the complexities of asynchronous publication, enabling the benefits of interoperability to be realized almost immediately.

As S-101 ENCs are gradually published, they can replace S-157 charts without the need to overhaul the entire system of data production, publication, and use, since all information would continue to be published and utilized according to the general S-100 requirements.

The S-157 Feature Catalogue is available as an XML document that conforms to the S-100 XML Feature Catalogue Schema (refer to S-100 Part 5) and implements the S-57 IHO Object Catalogue. For more details, see S-57 Appendix A, Chapter 1 - Object Catalogue. The table below presents the "Beacon Cardinal" object as described in different standards.

The underlying geometry of S-157 is constrained to level 3a, which supports 0, 1, and 2- dimensional features (points, curves, and surfaces) as defined by S-100 Part 7 – Spatial Schema. For more details, refer to S-101 ENC Product Specification 1.2.0, Chapter 4.8.1 - S-100 level 3a geometry.

S-157 portrayal is governed by the portrayal model defined in S-100. This model dictates how the Portrayal Catalogue is to be used in marine navigation systems. The Portrayal Catalogue specifies the symbology and portrayal rules for each feature/attribute combination listed in the Feature Catalogue.

S-157 adheres to the portrayal process defined in S-100 Part 9A - Portrayal (Lua) and requires the implementation of S-100 Part 13 - Scripting. The portrayal standard for cartographic information used is based on S-52.

S-157 employs the S-100 profile of ISO/IEC 8211 (refer to S-100 Part 10A) to encapsulate data. For a comprehensive description of the data records, fields, and subfields defined in the encoding, see Annex B of S-101 ENC Product Specification 1.2.0.

The limited application of the S-100 model to data created in accordance with the S-57 standard is artificial and lacks critical support. The proposed S-157 solution represents a coherent application of the universal S-100 model, enabling practical implementation of the declared interoperability in a short timeframe and with minimal costs. This approach does not negate the S-101 standard but makes the transition to it more systematic and user-friendly for all market participants, including standardizing institutions.

23.08.24.

A.Sabaydash
CEO
GeoPhone SW
sab@mkart.fi