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Production of Lights and Radio Signals
POLAR is a system for recording, editing, managing and publishing certain types of hydrographic data.
Specifically it is currently used for Lights and Radio Signals Vol 6 information.
Overview
POLAR maintains information in a central database which is accessed by a variety of client applications. The database can support hundreds of clients. The main client application is an Editor which can be used to inspect, edit and validate POLAR data. In addition there are publishing and administration applications.
Most clients of POLAR are viewers who use the Editor to inspect Lights and Radio Signals data. This is typically presented in the context of charts. The Editor uses a shared database of ENC and ARCS charts.
Data within the POLAR database is correct. It is carefully checked both automatically and procedurally so that the information can be regarded with a high degree of confidence. This is in marked contrast to many other UKHO data stores which represent information much closer to the unfiltered source. The benefit of this approach is that any export can be considered as a snap-shot of the true current state of the world information.
Workflow
The basic unit for managing information in POLAR is an Object. POLAR Objects include:
- Light
- A collection of sequences that make up a single navigation light
- Service Location
- Pilot Services, Vessel Traffic Services, etc.
- Publication
- A paper or digital export
- A geospatial display shows Objects in a geographical context. The display surfaces can use ARCS, ENC or WVS (World Vector Shoreline) background. Standard tools for pan, zoom and magnify are supported.
- A hierarchical or tree view organises Objects according to groupings such as type and area.
- A list view allows Objects to be sorted by any of the column types.
- Text pattern matching
- Phonetic name matching
- Geographic locations
- Geographic areas (polygons, chart boundaries)
- Data is overlaid onto charts running from a common chart database.
- The positions of Lights can be reconciled with those held in the FODB, a database of S57 chart data.
- Digital publication data is passed to the Admiralty Digital Publication (ADP) servers which manage remote updating through HTTP and SMTP.
- Paper publication data is sent to a Desk Top Publishing system
- Notices are sent to a 3rd party as XML.
Data is never deleted from the POLAR database. When an Object is modified it is stored with a new version number along with all the previous versions. When an Object is deleted then it is marked as deleted but not actually removed.
To modify a POLAR Object it is first checked out. That is, a local copy is made of the version held in the database. After editing, the modified version must be verified by a separate person before it can be checked back into the database. Once checked in, the Object becomes the new current version for that data. All the previous versions are retained.
All changes to the data are authorised and verified. A role based security system ensures that only specified people are assigned roles such as ‘editor’, ‘verifier’, etc.
The database contains thousands of Objects each of which can have multiple versions.
A flexible rules based system controls data integrity and helps with the management of safety critical data. Rules, established by the system Administrator, generate warnings and can control the workflow.
The Editor
Much of the underlying technology and GUI for the POLAR Editor is derived from CherSoft’s extensive experience in marine navigation and related systems. The Editor is the primary interface for POLAR and is used by Viewers, Editors and Verifiers. While essentially a sovereign system it is also designed to be sufficiently approachable and familiar as to be readily useable on a casual basis.
POLAR can manage many thousands of Objects so fast, intuitive mechanisms for navigating around the data are essential. There are three basic approaches:
In addition there are substantial searching facilities including:
The intent of the system is that data is handled in a product independent way. However the information can be previewed in the style of one of the digital or paper products. This allows editors to rapidly understand how the data will finally be presented while keeping the data distinct from publication issues.
Publications
A Publication Object is used to manage output from POLAR. Each Object corresponds to an entity such as a List of Lights Volume or a digital data set. The Publication Object defines which POLAR Objects are contained in the publication. It also tracks when instances of a publication are created.
Generic data can be extracted from the POLAR database as XML. Commercial data requires additional facilities.
Publication instances, for example a specific edition of List of Lights, are created using Wizards. These are stand-alone applications which step through the required decisions. From the perspective of someone creating a publication instance this is a very simple process.
Paper Publications
POLAR output for a paper publication is a single print ready file. Generating this requires collating the required Objects (specified in a Publication Object) and then formatting an appropriate document. Suitable fonts, templates, headers, footers, indexes and supplementary pages are all brought together into a single file ready to be previewed and then sent to the printer.
Notices to Mariners
A Notice is a mechanism for keeping a paper publication up to date.
When safety critical changes are made to an Object a copy of the Object data is used as a contribution to the weekly Notices. Production of notices is nearly automatic. Publication Objects track List of Lights and Radio Signals Objects and when they were issued. The contents of a Notice are essentially a copy of the new Object data. In the case of Radio Signals this is sometimes manually edited.
Creation of the final Notices uses similar mechanisms to the book publication. The end result is similarly a print ready file.
Digital Publications
Digital data for both List of Lights (ADLL) and Radio Signals (ADRS6) consists of base and update files. A base file contains a complete set of data for a specific date. An update file can be applied to a base file which then makes the base file identical to one for a later date.
Once a week new base files are created. At the same time a set update files are generated. These are typically made for each of the previous 52 weeks. A user of ADLL or ADRS can then update their data holding to a current data set using a single consolidated update file.
Connectivity
A key feature of POLAR is its ability to interconnect with other systems. That is, to become part of a larger system. Connectivity is achieved through a variety of standards based mechanisms in particular the use of XML.
Several components have already been introduced: