Last reviewed 16 Sept 2026 · 6 min read
Coordinate systems
World Coordinate System (WCS)
- The fixed, default coordinate system of every drawing.
- X-axis horizontal (positive to the right), Y-axis vertical (positive upward), Z-axis perpendicular to the screen (positive towards the viewer).
- The origin (0, 0, 0) is at the lower-left of the default view (it can be anywhere on screen after zooming/panning).
- All objects are ultimately stored in WCS.
User Coordinate System (UCS)
- A movable coordinate system defined by the user — origin and axis directions can be changed.
- Useful for drawing on inclined features, aligning with rotated buildings/grids, and 3D modelling on different faces.
- The UCS icon shows the current orientation; a square at the icon's base typically indicates WCS is current (depending on version).
Types of coordinates
Cartesian coordinates
A point is located by its X and Y distances from the origin: (x, y) or (x, y, z).
Polar coordinates
A point is located by distance and angle: distance < angle.
- By default, angles are measured anticlockwise (counter-clockwise) from the positive X-axis (East = 0°); 90° = North, 180° = West, 270° (or −90°) = South.
- Negative angles are measured clockwise.
Coordinate entry methods
| Method | Format | Meaning |
|---|---|---|
| Absolute Cartesian | x,y |
From the origin (0,0) |
| Relative Cartesian | @dx,dy |
Offsets from the last point |
| Absolute polar | d<θ |
Distance d from the origin at angle θ |
| Relative polar | @d<θ |
Distance d from the last point at angle θ |
| Direct distance entry | Move cursor in a direction, type distance | Uses the cursor direction (with Ortho/Polar for accuracy) |
- The @ symbol means "relative to the last point". Typing
@alone reuses the last point.
Dynamic input and coordinate defaults
- With Dynamic Input (F12) on, the second and subsequent points are relative by default (so typing
50,0behaves like@50,0). - To enter an absolute coordinate in dynamic input, prefix with # (e.g.
#100,50). - To force relative explicitly, use @.
- Settings can be changed in Drafting Settings → Dynamic Input.
3D coordinates
| Type | Format | Description |
|---|---|---|
| Cartesian (3D) | x,y,z / @dx,dy,dz |
X, Y and Z values |
| Cylindrical | d<θ,z / @d<θ,z |
Distance in XY plane, angle from X-axis in XY plane, and Z height |
| Spherical | d<θ<φ / @d<θ<φ |
Distance from origin, angle in XY plane from X-axis, and angle from the XY plane |
UCS command
Common options:
| Option | Function |
|---|---|
| World | Returns to WCS |
| Origin | Moves the origin, keeping axis directions |
| 3 Point | Origin, point on positive X-axis, point on positive XY plane |
| Object | Aligns UCS with a selected object |
| Face | Aligns with a face of a 3D solid |
| View | XY plane parallel to the screen |
| X / Y / Z | Rotates UCS about the specified axis |
| Previous | Restores previous UCS |
| Named | Save/restore UCS |
UCSICON controls the icon display; PLAN command shows the plan view of the current UCS.
Inquiry commands
| Command | Output |
|---|---|
| ID | Coordinates of a picked point |
| DIST | Distance, angle in XY plane, angle from XY plane, and delta X, Y, Z between two points |
| LIST | Properties of selected objects (layer, coordinates, length, area, etc.) |
| AREA | Area and perimeter of a polygon defined by points or of objects; add/subtract areas |
| MEASUREGEOM | Distance, radius, angle, area, volume |
| MASSPROP | Mass properties of regions/solids — area, perimeter, centroid, moments of inertia |