Precision
Ensure the precision required for your models.
There are several precision features available, The most common of which are polar tracking, object snaps, and dynamic input.
- Polar tracking. Snap to the closest preset angle and specify a distance along that angle.
- Object snaps. Snap to precise locations on existing objects, such as an endpoint of a polyline, the midpoint of a line, or the center point of a circle.
Polar Tracking
When you need to specify a point, such as when you create a line, use polar tracking to guide the movement of your cursor in certain directions.
For example, after you specify the first point of the line below, move your cursor to the right, and then enter a distance in the Command line to specify a precise horizontal length for the line.
By default, polar tracking is turned on and guides your cursor in a horizontal or vertical direction (0 or 90 degrees).
Object Snaps
By far, the most important way to specify precise locations on objects is to use object snaps. In the following illustration, several different kinds of object snaps are represented by markers.
Object snaps become available during a command whenever AutoCAD prompts you to specify a point. For example, if you start a new line and move your cursor near the endpoint of an existing line, the cursor will automatically snap to it.
Set Default Object Snaps
Enter the OSNAP command to open the Settings dialog and set the default object snaps, which are also called "running" object snaps. For example, you might find it useful to turn on the Midpoint object snap by default.
Recommendations
- Make sure that you zoom in close enough to avoid mistakes. In a densely populated model, snapping to the wrong object or the wrong point on an object can frequently happen.
- At any prompt for a point, you can specify a single object snap that overrides all other object snap settings. Right-click in the drawing area, and choose Snap Overrides from the menu, then choose the OSNAP point you want to use.
Object Snap Tracking
During a command, you can align points both horizontally and vertically from object snap locations. In the following illustration, you first hover over endpoint 1 and then hover over endpoint 2. When you move your cursor near location 3, the cursor locks into the horizontal and vertical location shown.
