Feature collection (Maritime Charting)

When collecting features, it is critical that you maintain coincident geometry. The best way to do this is to collect large areas first. Always start with the Dqyarea, then use those boundaries to collect other coincident features. The best method and most widely used is the Production Trace tool on the Production Editing toolbar.

When features are collected, they may be attributed before or after they are created. Use the Create Features window to set the attributes before you collect a feature, or you may choose a template. You may also set the attributes after the creation of the feature by using the Update Features window and updating the existing feature's attributes. All features, unless specified, are created with default attribution.

When collecting features that have values in units other than meters, you need to convert them using the Units Conversion tool on the Nautical DNC toolbar. Always input what you see on the chart. There is one important exception, however. If you have character fields that require values of units to be converted, you must convert them manually. The Units Conversion tool only works with numeric fields. You must also manually convert all note table entries.

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Use shortcut keys to perform certain functions from within the ArcMap editing environment.

Snapping environment

Many of the feature geometries captured for DNC are dependent on other features. The snapping environment is an important aspect of collection. When setting up the snapping environment, it is recommended that only snap to vertex be used. The exception is Dqyarea, which uses snap to edge because there are only corner vertices when the feature is first captured. Also, the order of feature classes in the snapping environment menu is the snapping priority that ArcMap uses to determine which feature it snaps to first.

Press the V key to easily identify vertices on existing features while adding new geometry. The V key highlights vertices on nearby features with a hollow square. Using this tool helps ensure coincidence between dependent features.

These dependencies are important during the beginning stages of extraction. For example, as you are digitizing the shoreline, consider reef, pier, obstruction, and other areas that may ultimately share that edge, and add vertices where these areas meet.

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When sketching features, think about how you will collect other features that connect to the feature you are currently collecting. Remember to place vertices at key intersections. This allows you to snap new features more easily.

For more information, see About snapping.

Area features

You should collect area features first. There are two reasons for this.

  1. DNC features are coincident with large polygons. Collecting them first allows you to use tools such as the Production Trace tool to share coincident geometry when capturing smaller features.
  2. Many of the topology rules rely on area features.

Always create Dqyarea first and work inward, collecting the largest areas first. Usually, your land and water areas are the largest. The Production Trace tool is the best method for collecting your area feature while maintaining coincident geometry.

As you become more familiar with the defined topology rules, you learn how they might benefit you. Some rules actually create the features you want, while others do not. This could be beneficial depending on the complexity of your chart.

Remember which features cannot overlap one another. Topology finds most of these errors for you. You must understand the concept in order to fix these errors. When collecting area features, keep a theme-based approach.

Use the Production TOC Manager toolbar to group your layers accordingly. If you are collecting features that exist within the same theme, they must not overlap, so keep the layers in the theme visible during collection. Use the Cut Polygons tool on the Production Editing toolbar or other methods to ensure no features overlap. There is an exception: limits may overlap one another.

A completely theme-based approach does not ensure that features do not violate certain spatial relationships. An example of this is land and water. Ground surface and open water exist in the same theme (ECR), so it should be easy to ensure that they do not overlap. However, depth areas, which are in the theme HYD, are a water feature, and these must not overlap land features either. It is necessary to consider these relationships during collection. If you follow the production flow strategy outlined above, you will minimize the number of errors created by overlapping features.

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Do not rely on topology to fix all your errors. It is faster to collect features the right way first.

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Remember to enter the values as they appear on the chart, except for character fields. Use the Units Conversion tool on the Nautical DNC toolbar to convert values that are in units other than meters.

Line features

Once you have created all your area features, you can create most of your line features using the Production Trace tool. Always have your target layer set in the Create Features window.

If you have to sketch a new line without using existing geometry, do not use the stream mode. This will generate too many vertices, which will cause unwanted validation errors. Also, place vertices where you will need them for snapping other features to that location.

Follow the theme-based approach when collecting line features. Lines must intersect other features from line feature classes when they exist in the same theme. If they do not exist in the same theme, they do not have to intersect. When collecting features that must intersect, use the Create and Intersect Features tool on the Create Features window. For example, when you create roads or railroads, these features must not only intersect themselves but also each other because they exist within the same theme.

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Always have your snapping environment set while using the Production Trace tool. This ensures that you snap to existing vertices or endpoints.

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You may use the Copy and Paste option to duplicate geometry between line feature classes.

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Remember to enter the values as they appear on the chart, except for character fields. Use the Units Conversion tool to convert values that are in units other than meters.

Point features

The geodatabase setup process generates point feature classes. When collecting point features, set the correct target layer in the Create Features window.

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Never snap features to point features. This generates VPF validation errors.

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Remember to enter the values as they appear on the chart, except for character fields. Use the Units Conversion tool to convert values that are in units other than meters.

Editing topology

Editing features that participate in a topology is similar to editing simple features. You use the same sketch tools to create new features. When you want to modify a feature that shares edges or nodes with other features in the topology, use the Topology Edit tool on the Topology toolbar.

When collecting features, you must consider the topological relationships that the new feature may have. If any shared edges need modification during a later edit session, you can use topology editing tools to keep feature coincidence complete. Using the Production Trace tool and other snapping agents enforces these relationships.

Saving and committing DNC edits

Save the edits you have made during an edit session at any time by clicking the Save Edits button on the Production Editing toolbar. If you quit ArcMap or stop editing, you are prompted to save or quit without saving if any edits were made since the last time you saved. While editing a workspace, you can roll back any changes since the last save. When you are working with a personal geodatabase, the edits are committed to the database when you save. When you are working with an ArcSDE geodatabase, the edits are saved to the version of the database you were working in. If the edits to the version are acceptable, the version can be reconciled and posted with any parent version or the default version of the database; otherwise, the version can be dropped along with any edits that took place in it. The versioning tools are available on the Versioning toolbar.

General guidance

Follow these guidelines while editing features:

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4/27/2014