Introduction to Digital Nautical Chart (DNC) production (Maritime Charting)

In the past, data was stored in a set or many sets of files that a limited number of people could access and edit. With a geodatabase as the data store, data is seamless and can be viewed and edited by multiple people. This minimizes the efforts required to bring file-based datasets into a single data store for seamless usability. The sources may include both image and vector in any number of projections, which do not need to be physically projected to a common projection to be usable in ArcMap.

Production environment

The ArcMap environment accommodates many tasks, from data automation to analysis and map production. There are many dockable toolbars that are not exposed and that must be exposed when required for a given task. Through the Customize menu, the ArcMap environment can be quickly adjusted. Select a task within the Toolbars environment option on the Customize menu, and toolbars are automatically added and removed to better accommodate the task. The Customize Mode command on the Customize menu also provides quick access to Production Mapping commands that are used less often. The Customize menu can also be used to support other task requirements.

Data quality

Data quality is ensured through several methods. In-process automated quality control is built into the database model and controls the available attribute values for many fields. Production Mapping extends the in-process automated quality control and includes tools that can be used to discover and log data errors for review and correction cycles. Both automated and manual quality controls are employed to ensure high-quality data.

Production database

Whether you are doing maintenance or production work, you need to use a geodatabase. With Digital Nautical Chart (DNC), you have four scale-specific geodatabases: Harbor, Approach, Coastal, or General. It is important that you choose the correct scale.

The geodatabase is a geographic database that provides services for managing geographic data, which include validation rules, relationships, and topological associations.

Once the database has been populated, it can then be used as input for creating hard-copy and digital products. ArcGIS for Maritime: Charting can be used to create map products with standard surround elements as well as reference systems and title information.

In a browser, browse to the template GDBs located in the Maritime Charting directory:

• 32-bit Windows operating systems—<Installation location>\Program Files\ArcGIS\EsriNautical\Desktop10.1\Dnc\Schemas\Built
• 64-bit Windows operating systems—<Installation location>\Program Files(x86)\ArcGIS\EsriNautical\Desktop10.1\Dnc\Schemas\Built

Note:

The version information at the end of the file name represents the release the model was associated with. It is recommended that you always use the latest version. The first two values represent the major release value. The second value represents the minor release value. The third value represents the service pack value, and the fourth value represents a patch. For example, 10.0.1.0 represents 10 Service Pack 1 and 10.1.0.0 represents 10.1 release.

Tasks

With the addition of the Production Mapping tools, tasks are streamlined by making the tools that are used to complete the task available with one click. Some of the tools on the Production Mapping toolbars are available through standard ArcMap menus, but most are not available with one click. The production environment, with the additional Production Mapping tools, can be quickly adjusted to the task, which streamlines the process.

Production process

There is an implied order to production. While quality control is discussed after data editing, it does not only need to be implemented at the end of production. Quality control processes should be run as needed to ensure the data is extracted properly throughout the project. The order in which features are extracted should be planned as part of a project process plan.

DNC editing considerations

There are many considerations when editing, maintaining, and quality controlling a database. Some things to consider are the purpose of the database, the intended use of the data, the scale the data represents, the target accuracy of the data extracted, and whether the accuracy target makes sense with the sources available. These are all important things to consider when developing a production plan and quality assurance program. Other things that may be necessary to consider are the diversity and experience of the workforce and its distribution. It is much more difficult to ensure the consistency of data extraction and quality control when the workforce is disconnected, which may impact both the production plan and the quality assurance (QA) program.

Before getting started with extraction for DNC, become familiar with the Individual Library Instruction (ILI) provided by the National Geospatial-Intelligence Agency (NGA). The ILI document contains all the standard information regarding the library and any deviations from the normal flow that NGA may request.

Suggested directory structure

An organized, logical, and standard directory structure for DNC data and information storage aids in production flow efficiency.

Managing the Table Of Contents window

There may be many feature classes of many types in the ArcMap Table Of Contents window (TOC). Because ArcMap draws features from the bottom of the TOC, feature order in the TOC is important. There may be many feature class order scenarios that make sense during editing. The Production TOC Manager toolbar can be used to remove empty feature classes, alphabetize them, and organize them by type. With the Production TOC Manager toolbar, having many feature classes in the TOC is more manageable.

Data frame display tools

The Tools toolbar provides the necessary tools for managing the display of the data. It also houses tools to interactively interrogate features and measure distances in the data frame.

Data dictionary

The database design must be understood to effectively extract data that is meaningful to the database. The data dictionary contains all the required features and the attributes that are used to describe the features. The database design reflects the data dictionary, and much of the content of the data dictionary is contained in the feature class domains. The ArcGIS 10.1 for Desktop help includes a digital data dictionary of the products that are installed.

Suggested production workflow

DNC production is a multiple-step process. It includes production preparation, feature creation and collection, quality control, and data conversion. The following steps outline the overall process.

1. Review ILI and prepare the Chart History document and Data Quality Worksheet.
   • Determine the scale of the GDB to be produced and get the template GDB.
   • Become familiar with any deviations from normal production flow for the library.
2. Set up the DNC ArcMap environment.
3. Populate the template GDB with data in one of the following ways:
   • Use a new collection of data.
   • Import existing vector data.
4. Create Dqyarea.
5. Georeference DNC images.
6. Configure the DNC database for validation.
7. Create ECR features.
   • Copy Dqyarea to Ecrarea.
   • Cut up Ecrarea into ground surface elements, open water, and islands.
8. Create HYD features.
   • Copy open water from Ecrarea to Hydarea.
   • Cut up Hydarea into different depth curve areas.
   • Use depth curve areas to create depth lines.
9. Capture OBS features.
10. Capture POR features.
11. Capture CUL features.
12. Capture remaining features (including notes.rat).
13. Review and incorporate the NGA List of Lights or United States Coast Guard (USCG) Light List.
14. Review and incorporate the Notice to Mariners.
15. Perform extraction quality control (QC).
16. Complete the independent QC cycle.
17. Perform unit conversion.
18. Perform data migration.
19. Convert to VPF.
20. Complete a VPF validation cycle.