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Parcel Editor - The Snapping Tool and Checkbox

Snapping checkbox

Snapping is an important concept when editing lines. It is important to make your line theme 'clean' so you can build it; you must snap the endpoints of every line to the endpoints of other lines so that they form closed shapes, which will become polygons when you build. When you have the 'Markers' checkbox checked (this is the default), dangles (line endpoints that do not connect to other line endpoints) will be shown as red dots.

To snap two endpoints together, zoom in close to the area you are editing and click the Snapping checkbox on. You will then drag a circle on the View's display whose radius will equal the snapping distance (how close two features need to be so they will snap together). [If you hold the mouse cursor over the snapping checkbox, the popup box will tell you if snapping is on and what the radius is (in map units)] When you set snapping on, you will be placed automatically into Vertex Edit mode (see 'Vertex Edit tool') and you will be able to select lines and move their endpoints around so they snap to other endpoints [you are placed into this mode because the Vertex Edit tool is the tool you will use most for snapping--but you can always switch to any other tool, i.e. the Draw Line tool. In Vertex Edit mode, you will not be able to see the red dangle markers; however you can switch back and forth between Vertex Edit mode and regular Select mode by clicking the Vertex Edit tool and the Select Feature tool]. Select a line, position the mouse cursor over its endpoint, and, pressing and holding down the mouse button, drag the endpoint to within snapping distance of another line's endpoint (ArcView doesn't like you to snap a line's two endpoints to each other), and the two will snap together. If you then click on the Select Feature tool, you will see that the endpoint is no longer marked with a red marker.

With snapping on, you can use the Draw Line tool to add lines, and if you start or end the line within the snapping distance of another line's endpoint, it will snap to it. Make sure you zoom in as far as practicable before you set snapping on, because when you snap a line's endpoint, every vertex in that line will try to snap to something. You want the snapping radius to be as small as possible to avoid unexpected vertex movement, and you should examine your lines after snapping to make sure no unwanted movement has occurred. The snapping radius will remain a constant distance in map units; that is, if you zoom in or out, the radius won't remain the same size relative to the screen, but rather will be the same relative to distance on the 'ground' as represented by the map. Snapping will remain on until you turn it off by clicking the checkbox off, or use one of the tools that automatically turn it off (Draw Survey, Split, Rotate, or Move). These tools turn snapping off to avoid unwanted snapping. When you click the Snapping checkbox on, you can then set the snapping tolerance by dragging a circle on the display, but if you choose a new tool without setting the tolerance this way, the tolerance will be set to the last snapping tolerance you used (unless that tolerance is extremely large relative to your zoom extent). This is so you don't have to reset the snapping tolerance every time it gets turned off.

QuickSnap tool

The QuickSnap tool is designed to help you snap line endpoints together more rapidly than is possible with the standard Snapping mode. It has three different modes, which you can control by holding down the Shift and Control keys while using it. To use it, click on the tool and then click-and-drag a circle on the map display.

All modes let you drag a circle on the map display and any line endpoints that fall inside the circle get snapped together. The exception is that if both of a line's endpoints fall inside the circle they will NOT both get snapped together. The three modes determine where the endpoints get snapped to.

The default mode (don't hold down Shift or Control while dragging the circle) will snap all the line endpoints to the line endpoint (node) that is closest to the center of the circle you drag (this is the first place you click when dragging the circle). This is used when you want to snap several lines to a particular line's endpoint.

The second mode (hold down the Shift key while dragging the circle) will snap all the line endpoints to the center of the circle you drag (this is the first place you click when dragging the circle). This is used when you want to snap several lines to a particular place that is not a line endpoint.

The third mode (hold down the Control (Ctrl) key while dragging the circle) requires you to have a point theme as the first active theme in the View. All the line endpoints will snap to the point feature (in the point theme) that is closest to the center of the circle you drag (this is the first place you click when dragging the circle). This is particularly useful if you have GPS lines with GPS intersection points, parcel boundaries with boundary point markers, etc.

The QuickSnap tool is a very efficient way to snap line endpoints together, whether they be roads, trails, parcel boundaries, or any other line data. Another benefit is that other vertices in the lines will not attempt to snap themselves in ways you do not intend. When you use this tool, regular snapping mode (the Snapping checkbox) will be turned off automatically.

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This document was created by DEM/ NWF. Contact: DEM/ NWF.