A case study of the production of an S-57 ENC with CARIS tools
The advent of the Electronic Chart Displaying and Information System (ECDIS) and the availability of an accurate positioning system, such as the Differential Global Positioning System (DGPS), were the driving technologies for a new digital hydrographic product. The Electronic Navigational Chart (ENC) is a new hydrographic product, recognized by the international marine instances as the equivalent of the traditional paper chart. The production of ENCs is being supported by the use of Geographic Information System (GIS) tools to meet the requirements of the International Standard for the Exchange of Hydrographic Data, documented in the IHO special publication No 57 (S-57). The S-57 document makes the use of the object-oriented concept to model the real world into a computer-based format. The aim of this report is to study the production of an ENC with tools from Universal Systems Limited (USL), CARIS and OBMAN, to make recommendations and suggestions not only for software enhancement but also to contribute to the optimization procedures within an Hydrographic Office (HO) currently producing both paper and electronic charts. This report is structured in seven chapters. This first two define the problem of building an ENC within an HO and introduce an historical background to support the discussion between raster and vector charts. The Object-Oriented (O-O) concept in general and its meaning for the S-57 standard, in particular, is described in chapter 3. The use of “dedicated methods” in O-O is particularly important within the S-57 ENC because it allows an object to be displayed with different geometries depending on the scale chosen. The S-57 standard is explained in detail in chapter 4, while chapter 5 introduced the CARIS tools used. Chapter 5 also compares two different ENC viewers (ECVIEW and SeeMyENC!). The steps followed by the author to build an S-57 ENC are also contained in this chapter. An example is the need for an appropriate layering of the data whenever a CARIS file is built for both paper and electronic chart production. The author also suggests a quality control tool to check for inconsistences and distortions on the shapes of the feature objects after the filtering of the point data (S-57 standard).