4. CREATING AND EDITING DATA
4c. Creating and editing lines
4c. Creating and editing lines
This is the infamous “Digitizing your contacts” portion of making a map. Depending on how complex your map is, this can take minutes to hours to days. Personally, I’d recommend having some good music and a cup of coffee handy. Many of the steps here are similar to editing points (e.g. changing the symbology for the lines), so things won’t be explained in as much detail.
IMPORTANT: When editing your lines, be sure to go to the Editor Toolbar and Editor –> Save Edits OFTEN!
Also, please read through this portion and the next “Managing Topology” before starting to edit your lines. It’s much more efficient to manage the topology as you edit your lines while working in on your project, but easier to explain them as two separate steps here.
Here are the steps to editing lines:
1. Before creating any lines, let’s change their symbology to match what standards used on geologic maps. Open up the “Layer Properties” window for your line feature class, and go to the “Symbology” tab. It looks slightly different than the same tab for the bedding layer. Choose Categories –> Unique values. Next, double-click on the line symbol to open the “Symbol Selector” window and choose the appropriate line style. Repeat for all your lines, then click “OK”.
2. Go to the “Create Features” window, and select the type of line you want to create. Notice that all the lines that you created waaaay back when in ArcCatalog are present in this window, and now have the appropriate symbology that you applied.
3. Before you actually start creating you lines, turn on the “Snapping” tool. This will allow ArcMap to snap your lines together (to vertices or endpoints) and thus alleviating some topological errors. Go to Customize –> Toolbars –> Snapping to turn on this tool.
Under the “Snapping” drop-down menu, make sure that the check box next to “Use Snapping” is selected. By “snapping” your lines, you’re making them connect to other lines and avoiding open polygons. This is known as “managing your topology”. However, eventually you’ll make a topological error and have to fix it. We’ll cover that in the next section.
4. Choose the “Straight Segment” tool from the Editor Toolbar and start creating your lines! Each time you click the mouse, you create a vertex of a line. The more vertices you add, the smoother the curves on your lines will look. Double-click to finish the line, or use F2.
5. Remember- when you want to change the type of line that you are creating, click on the appropriate line type from the “Create Features” window. If you accidentally create the wrong type of line in one place- it’s an easy fix. Using the Editor Arrow from the Editor Toolbar, select the line whose type you wish to change. The line will then turn BLUE, indicating that it is selected. From the “Attributes” tab in the “Create Features” window, you can use the Attribute Table to change the line type.
6. Keep at digitizing your lines, making sure to go Editor –> Save Edits often.