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Common line editing tasks

Release 9.3
Last modified May 14, 2009
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Creating lines that connect to the ends of other lines

Many times when you are creating new line features, you want them to connect to the endpoints of other lines. When digitizing transportation routes, the street lines should meet at their ends, for example. To ensure that new lines meet at the ends of existing lines, you can use the snapping environment to help you properly place the endpoints.

  1. Open the Snapping Environment dialog box, turn on end snapping for the line layer to which you want to connect at endpoints, and move that layer up the list of layers to give it a higher snapping priority. Close the dialog box.
  2. Set the target layer to the line layer into which you want to create new features.
  3. Set the task to Create New Feature.
  4. Click the Sketch tool Sketch.
  5. Snap to the end of an existing line, then click to add a start vertex in the new line.
  6. If you want the end vertex to meet at an existing line, make sure your end vertex snaps when you add the vertex and finish the sketch.
If you already have some line features that you want to connect, here are several options:


Creating lines without dangles

Lines should often connect to each other. When they don't, there may be errors in your dataset or valid exceptions to this guideline. For example, when tracing a stream network, the ends of smaller streams should connect to a river. When mapping a transportation network, street features should connect to each other unless they're dead ends or culs-de-sac. To ensure that new lines don't have dangles, you can use the snapping environment to help you properly place the endpoints.

  1. Open the Snapping Environment dialog box and turn on end snapping for the line layer into which you want to create new features. Close the dialog box.
  2. Set the task to Create New Feature.
  3. Click the Sketch tool Sketch.
  4. When you create new features, make sure the endpoints snap to existing lines.
Once your features are created, using an ArcEditor or ArcInfo license, you can use geodatabase topology to identify and fix any remaining dangles. Apply the Must Not Have Dangles rule to the line feature class, then identify and fix any errors. If a dangle error is a valid case (such as a cul-de-sac), you can mark it as an exception.


Extending and trimming lines

If you have lines that should connect to other lines but are too long or too short to reach the line they should intersect, you can quickly extend and trim these lines so they meet. For example, if you have road lines that are too long and overlap a body of water, trim the roads so they touch (and therefore end) at the water's edge.
You can extend or trim lines by drawing a new line sketch where the lines should intersect. You can also select an existing line to which you want other lines to connect, then click those lines, and they will be extended or trimmed to match it.
Learn how to extend a line
Learn how to trim a line


Splitting a line into two or more lines

Sometimes you need to split an existing line into two or more lines. You can split lines in several ways such as clicking where you want the split to occur, at a distance from an endpoint, or into a number of new line features.
Learn how to split a line


Reshaping a line

You can reshape a line to match an existing line or a feature on an image. For example, after a street is rerouted, the new edge of the pavement can be used to modify nearby features such as a sidewalk, parcel boundary, or a bus route that follows the road. You could also use an aerial photograph as a guide to trace the road's new shape.

  1. Build a map topology in which the line feature class you want to reshape participates.
  2. Use the Topology Edit tool Topology Edit on the Topology toolbar to select the line you want to reshape.
  3. Set the target layer to the line layer to be reshaped.
  4. Set the task to Topology Tasks: Reshape Edge.
  5. To reshape a line to match an existing feature, use the Edit tool to select the line or polygon edge you want to trace, then use the Trace tool to draw a sketch of the reshaped line. You can press the O key to set options.
  6. To reshape a line by tracing over an image, for example, just use the Sketch tool to draw a sketch of the reshaped line.
  7. Finish the sketch when you're done.
The steps above describe using a map topology and the Reshape Edge task. However, you can also use the Reshape Feature edit task, which does not require a topology. With Reshape Feature, you just need to select the line to reshape, then draw a sketch. However, only the Reshape Edge task allows you to edit shared geometry and use the Trace tool to draw the sketch of the reshaped portion of the line.


Creating cul-de-sac lines

There are several ways to create a cul-de-sac line, which is the end of a dead-end street or alley that widens to provide a circular turnaround for vehicles.
If you are working with precise measurements, such as with survey plans or data with COGO attributes, use the Cul-de-sac command on the COGO toolbar to create the feature.
Otherwise, you can use the regular editing tools, switching between them, to construct a cul-de-sac shape. For example, you can draw the straight segment using the Sketch tool, switch to a tool that allows you to create an arc, then switch back to the Sketch tool to create the remaining straight segment.

  1. Set the target layer to the line layer into which you want to create new features.
  2. Set the task to Create New Feature.
  3. Click the Sketch tool Sketch.
  4. Draw the straight segment of the line, but don't finish the sketch.
  5. Click a tool on the tool palette that will allow you to create a curved segment, such as the Arc tool.
  6. Create the arc segment, but don't finish the sketch.
  7. Change back to the Sketch tool, draw the remaining segment, then finish the sketch.


Creating lines offset from other features

There are several methods you can use to create lines representing the features offset from other features such as the edge of the pavement, curbs, or rights–of–way. Both the Trace tool and the Copy Parallel command allow you to specify an offset distance and how you want corners to be created.
Creating offset lines using the Trace tool
The Trace tool helps you create segments that follow existing segments. You can choose to trace all or a portion of lines or polygon edges to make a new feature. Suppose you want to add a new road casing or easement that is offset 15 feet from the front of a parcel subdivision. You could use the Trace tool to trace along existing lot line features instead of typing the angle and length of each segment, or manually digitize vertices and segments.
Learn how to use the Trace tool
Creating offset lines using the Copy Parallel command
The Copy Parallel command creates a line feature parallel to an existing feature at an offset distance you specify. Copy Parallel only allows you to copy line features.
Learn how to use the Copy Parallel command


Flipping the direction of lines

Flipping a line reverses its direction so the last vertex of the sketch becomes the first, thereby changing the from-to direction of the feature. Flipping can be useful for editing lines in which the line orientation represents flow direction and when using symbols, such as arrowheads, that depend on the orientation of the line.

The Editor > Flip command allows you to reverse one line at a time. If you have many lines that you want to reverse at once, try the Flip Command developer sample available from edn.esri.com or the Flip Line Direction .NET code snippet.

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