Keywords

1 Introduction

The development of the S-100 framework is a major step in the collaboration of different worlds and products. Means for maritime and inland navigation will come closer to each other and information will be displayed in the same way in the wheelhouse. Notices to Mariners (S-124), AIS AtoNs (S-201), Water level information (S-104), Bathymetric information for Inland (S-402), … S-100 will handle them all in the same way and the interoperability will be set.

The development of the S-401 for inland electronic navigational charts is ongoing for several years and getting in a phase of testing. Although some elements have to be developed, the S-401WG is looking for manners to convert and test the product.

In the next presentation an overview will be given of the status of all elements within S-401.

2 Data Dictionary and Portrayal

2.1 Product Specification

One of the most important decisions the IEHG has taken concerned the compatibility between the maritime S-101 and the future inland S-401 standard. It had to possible to use both charts on the same S-100 viewer and therefore the S-401 has to be in line as much as possible with the maritime standard. This decision lead to the procedure that the development of S-401 would always run behind the development of S-101.

Once the first edition of the S-101 Product Specifications were published by IHO, the IEHG finalized their adapted S-401 Product Specification in December 2019. To make the publication possible, some issues had to be postponed and temporarily removed from the final document. The interoperability and validation were two of such issues which weren’t solved yet.

Certainly the interoperability is a main issue for which a good solution is needed. The combination of S-products in the viewer must be handled in a correct way. Which feature must be visualized and which not. Which attribute is prior and must be displayed on top?

On the moment this paper is written, IHO is developing the S-98 standard which describes the interoperability for S-100. In the first draft, only S-101 has been taken into account as a base cell. This lead to many questions in the Inland ENC Harmonization Group:

  • How will S-401 interact with the base cell of S-101?

  • How will the S-100 viewer determine what to visualize?

  • Can’t the navigator chose between a maritime chart and an inland chart?

  • …

As a solution IHO has decided to amend S-401 as possible base cell as well. Hereby the skipper can chose between S-101 and S-401 as base layer on his screen.

2.2 Feature Catalogue

The Feature Catalogue is the overview of all features, attributes and enumerations that can be encoded into a chart. The existing Inland ENC feature catalogue is based on the S-57 format. Three type of can be distinguished:

  • Specific Inland features (not used in maritime)

  • Maritime features (also used in inland)

  • Maritime features used in inland but with other attribute values

To get a complete list of the features, attributes, values and enumerations for the S-401, all maritime elements were copied into the new inland feature catalogue. The IHO Geo information Registry allows all domains (hydro, inland, …) to register features and attributes into the registry database and avoids that different domains add or change features which are used in other domains. The Feature Catalogue Builder is connected to this database and allows the domain control body to add all available features (attributes) to a specific feature catalogue.

The whole process of amending, changing, updating the inland specific features, registering them in the IHO GI Registry and creating the feature catalogue has been finalized and lead to the S-401 FC edition 1.0.0.

2.3 Portrayal Catalogue

Once all features are described, they have to be visualized in the S-100 viewer. Lines, areas, points, colors and symbols need to be defined. The description of colors is done in different style sheets (day, dusk, night), while lines and area fills are composed in XML-files. On the other hand all symbols are in the SVG format. Some of the portrayal elements, were rather easy to create but others (e.g. symbols) needed some expertise.

For a lot of features the visualization is depending on the condition. Attribute values, combinations of features, lead to different visualization. In S-57, the conditions were described in the five look up tables. But S-401 isn’t using ASCII look up tables anymore but separate LUA scripts.

Before the S-401 scripts could be developed, all the conditions needed to be determined. Therefore all the inland conditions were compared with the maritime conditions and as a result combined look up tables were created. The last step was to decide which S-101 LUA scripts could be used and which scripts needed to be developed from scratch.

At the moment this paper is written, the development of the S-401 LUA scripts is ongoing.

2.4 Data Classification and Encoding Guide

Although the most important elements for the S-401 are described in the previous overview, it will be very difficult to produce a chart without instructions and guidelines. For Inland ENCs the IEHG created the Encoding Guide which describes real world entities. For the manufacturer of charts, the instructions are a big help.

For S-100 products IHO has developed a Data Classification and Encoding Guide. The DCEG is a document with the same purpose as the Inland Encoding Guide but the big difference is that the DCEG is describing every feature separately instead of describing real world entities with the linked features.

The IEHG had to decide whether they would follow this approach or not. The existing Encoding Guide was a helpful document and without the possibility to amend these entities, the DCEG wouldn’t be of any value. On the other hand the IEHG had decided to stay in line with S-101 as much as possible.

After the acknowledgment from IHO that it would be possible to add free text and pictures which wouldn’t be lost by updating the DCEG, IEHG decided to use the DCEG in the future.

3 Next Steps/Issues

Before the S-401 can be implemented, a thorough testing has to be done. Testing in a viewer with the S-401 Feature Catalogue and Portrayal Catalogue and with S-401 charts. Converting existing IENCs will be made possible by the manufacturers of charting software and will be one of the next steps of the RIS COMEX team. But for the conversion of S-57 cells some rules and conversion guidelines have to be set. This will be done in the ‘S-57 ENC to S-401 conversion guidance’. This document will describe the default values of attributes, how old values have to be translated into the new values and more.

At this moment the document is in preparation and hopefully finalized until the end of the year.

For the testing itself, the IEHG is relaying on the S1OOP (S-100 Open Online Platform) which is developed by KHOA. This online platform will enable the possibility to load different catalogues in the viewer and load charts of different products into the software. This will allow the project team to test not only the catalogues but also the charts.

One of the major issues the IEHG is facing in the development of S-401, is the interoperability. It must be possible to combine S-401 with other S-products in the S-100 viewer without losing important information. The displaying of features and attributes that come from other S-products may not interfere with the features and attributes of the S-401 base cell. This interoperability must be enforced and regulated. Even the interoperability with S-101 has to be described. In a first step IHO will describe this interoperability for S-101 in the product specification and the S-98. Once IHO has finalized the interoperability it’s up to the IEHG to get in line with S-101.

4 Conclusions

The development of the S-401 for electronic inland navigational charts is a process that is ongoing and will take a couple of years before it can be implemented. Due to the compliance with S-101, the IEHG is relying on the development within IHO and therefore the IEHG is working together with the S-101 working groups. This will prevent any inconsistencies between the two worlds.