Creating geodetic features

You can create geodetic features—lines, circles, and ellipses—that are spatially accurate and geodetically correct in any projection. For example, if you are creating a feature that spans a large distance, such as an airplane's flight path across an ocean or the effective range of a weapon, you should use a geodetic feature. For an overview of geodetic features and more information on the distortion they account for, see About geodetic features.

You can enter coordinates for whole features or feature segments by clicking the map or by typing the values. You can specify the location as a longitude-latitude coordinate pair, a Military Grid Reference System (MGRS) grid location, a U.S. National Grid (USNG) location, or a Universal Transverse Mercator (UTM) coordinate. Click the Units button to choose the units you want. For guidelines on specifying coordinates, see About distance units and editing.

Direction is specified in the angular units specified on the Editing Options > Units tab. Distances, such as the radius or axis length, are specified in map units of the data frame by default. You can enter values using different units by clicking the Units button next to the text box. For example, when the map units are decimal degrees, clicking the Units button allows you to enter values in distance units, such as kilometers.

Note:

Geodetic features contain densified geometry, which is a shape created by a series of connected vertices. For example, a densified curve is composed of a succession of points along the entire path of the curve, whereas a Bézier curve is smooth. Densified geometries require more resources to store and manipulate and are more difficult to edit than standard geometries. Editing or moving geodetic features makes them non-geodetic, so if you need to change or move a geodetic feature, re-create it instead.

1. In ArcMap, start an edit session with either line or polygon layers.
2. Click Construct Geodetic on the Advanced Editing toolbar.

   The Construct Geodetic dialog box appears.

3. Choose the target in which the new feature will be created.
   • If you have feature templates for the layers in your map, click the Template button and click the template to use to create the new feature. You can also double-click the preview of the template to choose a different template.
   • If you do not have feature templates, click the layer in which to create the feature.

Note:

The list of available feature templates (or layers) is determined by the type of geodetic feature you are creating. Geodesic circles and geodesic ellipses allow you to create line or polygon features, so both line and polygon feature templates are listed. However, if you choose to create the other types, only line feature templates are shown.

4. Click the Type drop-down arrow and click the type of geodetic feature you want to create. For a description of each type, see About geodetic features.

   The Construction area of the dialog box changes to reflect the type you selected.

5. If you are creating a geodesic line, great elliptic, or loxodrome:
   1. Type the starting x- and y- coordinate values. You can also click the Interactive Start Point Selection tool , then click the map display to set the start point.
   2. Click the Segment arrow to set whether you want to create the segment by entering a coordinate for the end point or by a distance and bearing direction.
   3. Enter the end coordinate or the distance and direction.
   4. If you want to create a multi-segment line, click Add so the current end coordinate will become the start coordinate for the next segment. The Add button becomes enabled when you have entered two valid coordinates for points, directions, distances, and lengths.

Tip:

To add multiple segments quickly, you can use the TAB key to move through the coordinate entry boxes, then press ENTER to add the segment. You can press ESC if you need to cancel creating a multi-segment feature.

6. If you are creating a geodesic circle:
   1. Type the center x- and y- coordinate values. You can also click the Interactive Start Point Selection tool , then click the map display to set the center point.
   2. Type the radius value.
7. If you are creating a geodesic ellipse:
   1. Type the center x- and y- coordinate values. You can also click the Interactive Start Point Selection tool , then click the map display to set the center point.
   2. Type the major axis, minor axis, and direction values.
8. As you enter locations, you see a preview of the feature on the map. Once you are ready to create the feature, click the Create button.
9. Repeat these steps to create additional features. Close the Construct Geodetic dialog box when you are finished creating features.

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