1.2Precision drawing: object snaps (Osnap), grid, Ortho mode & polar tracking
AutoCAD's precision relies largely on object snaps (Object Snap, or Osnap). They let you point exactly at a key point of an existing entity: the endpoint of a line, the midpoint, the center of a circle, an intersection, a perpendicular, a tangent… Without them, it's impossible to connect geometry cleanly.
Alongside snaps, other drafting aids ensure rigor: Ortho mode (horizontal/vertical drawing), polar tracking (predefined angles), object snap tracking (aligning to existing points), the grid and snap resolution. Well configured, these aids make the cursor "stick" automatically where it should: that's the secret of a drawing that is both fast and rigorously accurate.
Section vocabulary
- Object snap (Osnap)
- An aid that "magnets" the cursor onto precise points of objects (endpoint, midpoint, center, intersection…).
- Ortho
- Mode constraining drawing to horizontal and vertical. Toggle with F8.
- Polar tracking
- Guides drawing along predefined angles (0°, 30°, 45°, 90°…) with temporary alignment lines.
- Object snap tracking (Otrack)
- Aligns a new point onto existing snap points via temporary tracking lines.
- Grid / Snap
- Grid: a visual aid grid. Snap: the cursor locks onto regular steps.
What are object snaps (Osnap) used for?
In practice — Drawing exactly with snaps
- Enable running snaps (F3) and configure a few of them: endpoint, midpoint, center, intersection.
- Draw a line starting exactly from the endpoint of another, then another line passing through the midpoint of a segment.
- Enable Ortho (F8) and polar tracking (F10): draw perfectly horizontal/vertical lines and 45° lines.
- Use object snap tracking to place a point aligned with two existing endpoints, without drawing any auxiliary object.
Key points to remember
- Snaps (Osnap) magnet the cursor onto the precise points of objects.
- Endpoint, midpoint, center, intersection, perpendicular, tangent…: the most used.
- Ortho (F8), polar tracking (F10) and object snap tracking (F11) make drawing more reliable.
- Well configured, these aids make drawing both fast AND accurate.
Frequently asked questions
My cursor doesn't snap anywhere, what should I do?
Check that snaps are enabled (F3 key) and that the desired modes are checked in their settings (right-click the Snap icon then Settings). An unchecked snap won't work. Conversely, if too many snaps are active, the cursor "hesitates"; only enable the ones you need, and use a temporary override (Shift+right-click) for a precise point when needed.
What's the difference between object snap and snap resolution?
Object snap (Osnap) locks the cursor onto points of EXISTING objects (endpoint, center…). Snap resolution (Snap, F9) locks the cursor onto a regular-step grid in empty space, regardless of objects. The first is used a lot (precise drawing relative to existing geometry) and the second more rarely. Don't mix them up.