The S-57 driver module produces features for all S-57 features in one or more related S-57 data files. An S-57 dataset can be a directory (in which case all S-57 files in the directory are selected), an S-57 catalog file (in which case all files referred to from the catalog are selected) or an individual S-57 data file.
S-57 feature objects are translated into features. S-57 geometry objects are automatically collected and formed into geometries on the features. Geometry objects are not separately accessable with the S-57 reader.
The S-57 reader depends on having two supporting files, s57objectclasses.csv, and s57attributes.csv available at runtime in order to translate features in an object class specific manner. These should be in the directory pointed to by the encironment variable S57_CSV, or in the current working directory.
Note that the S-57 Reader does not support S-57 update files in a useful manner at this time. S-57 update files contain information on how to update a distributed S-57 data file. While they can be read, they are not currently used to create an updated data view of the original file.
There is no update or creation support in the S-57 driver.
Each feature type has a predefined set of attributes as defined by the S-57 standard. For instance, the airport (AIRARE) object class can have the AIRARE, CATAIR, CONDTN, CONVIS, NOBJNM, OBJNAM, STATUS, INFORM, NINFOM, NTXTDS, PICREP, SCAMAX, SCAMIN, TXTDSC, ,RECDAT, RECIND, SORDAT, and SORIND attributes. These short names can be related to longer, more meaningful names using an S-57 object/attribute catalog such as the S-57 standard document itself, or the catalog files (s57attributes.csv, and s57objectclasses.csv). Such a catalog can also be used to establish all the available object classes, and their attributes.
The following are some common attributes, including generic attributes which appear on all feature, regardless of object class. is turned on.
Attribute Name Description Defined On -------------- ----------- ---------- GRUP Group number. All features OBJL Object label code. This number All features indicates the object class of the feature. RVER Record version. AGEN Numeric agency code, such as 50 for All features the Canadian Hydrographic Service. A potentially outdated list is available in agencode.txt. FIDN Feature identification number. All features FIDS Feature identification subdivision. All features LNAM Long name. An encoding of AGEN, All features FIDN and FIDS used to uniquely identify this features within an S-57 file. DSNM Dataset name. The name of the file All features the feature came from. Used with LNAM to form a unique dataset wide identifier for a feature. INFORM Informational text. Some features NINFOM Informational text in national Some features language. OBJNAM Object name Some features NOBJNM Object name in national Some features language. SCAMAX Maximum scale for display Some features SCAMIN Minimum scale for display Some features SORDAT Source date Some features