UCS

Quick Reference

See Also

Understand the User Coordinate System (UCS)

Manages user coordinate systems.

Access Methods

Button

Ribbon: View tab

Coordinates panel

WorldNot available on the ribbon in the current workspace

Menu: Tools

New UCS

WorldNot available in menus in the current workspace

Toolbar: UCS

List of Prompts

The following prompts are displayed.

Specify Origin of UCS or [Face/NAmed/OBject/Previous/View/World/X/Y/Z/ZAxis] <World>:

Specify Origin of UCS

Defines a new UCS using one, two, or three points. If you specify a single point, the origin of the current UCS shifts without changing the orientation of the X, Y, and Z axes.

If you specify a second point, the UCS rotates around the previously specified origin point such that the positive X axis of the UCS passes through the point.

If you specify a third point, the UCS rotates around the X axis such that the positive Y half of the XY plane of the UCS contains the point.

The three points specify an origin point, a point on the positive X axis, and a point on the positive XY plane.

NoteIf you enter the coordinates for a point and you do not specify a Z coordinate value, the current Z value is used.

Face

Aligns the user coordinate system to a face on a 3D solid.

Select a face by clicking within the boundary or on an edge of the face. The UCS X axis is aligned with the closest edge of the original face selected.

Next: Locates the UCS on either the adjacent face or the back face of the selected edge.
Xflip: Rotates the UCS 180 degrees around the X axis.
Yflip: Rotates the UCS 180 degrees around the Y axis.
Accept: If you press Enter, accepts the location. The prompt repeats until you accept a location.

3D solids can be created in AutoCAD.

Named

Save and restore commonly used UCS orientations by name.

Restore

Restores a saved UCS so that it becomes the current UCS.

Name: Specifies a named UCS.
?—List UCSs: Lists the names of currently defined UCSs.

Save

Saves the current UCS to a specified name.

Name: Saves the current UCS with the specified name.

Delete

Removes the specified UCS from the list of saved user coordinate systems.

?—List UCSs

Lists names of user coordinate systems and provides the origin and X, Y, and Z axes for each saved UCS relative to the current UCS. If the current UCS is unnamed, it is listed as WORLD or UNNAMED, depending on whether it's the same as the WCS.

Object

Aligns the user coordinate system to a selected object.

The positive Z axis of the UCS is aligned perpendicular to the plane in which the object was originally created.

The following objects cannot be used to align a UCS: 3D polylines and xlines.

For most objects, the origin of the new UCS is located at the nearest vertex to where you select the object, and the X axis is aligned with an edge or is tangent to an edge. For planar objects, the XY plane of the UCS is aligned with the plane in which the object is located. For complex objects, the origin is relocated, but the current orientation of the axes is maintained.

For objects other than 3D faces (available only when viewing AutoCAD drawings), the XY plane of the new UCS is parallel to the XY plane in effect when the object was drawn. However, the X and Y axes can be rotated differently.

The new UCS is defined as shown in the following table.

Define a UCS by selecting an object
Object	Method of determining UCS
Arc	The center of the arc becomes the new UCS origin. The X axis passes through the arc endpoint that is closest to the selection point.
Circle	The center of the circle becomes the new UCS origin. The X axis passes through the selection point.
Dimension	The midpoint of the dimension text becomes the new UCS origin. The direction of the new X axis is parallel to the X axis of the UCS in effect when the dimension was drawn.
Line	The endpoint nearest the selection point becomes the new UCS origin. The new X axis is set so that the line lies in the XZ plane of the new UCS. The line's second endpoint has a Y coordinate of zero in the new UCS.
Point	The point becomes the new UCS origin.
2D polyline	The start point of the polyline is the new UCS origin. The X axis extends along the line segment from the start point to the next vertex.
2D Solid	The first point of the solid determines the new UCS origin. The new X axis lies along the line between the first two points.
Text, block reference, attribute definition	The insertion point of the object becomes the new UCS origin, and the new X axis is defined by the rotation of the object about its extrusion direction. The object you select to establish a new UCS has a rotation angle of zero in the new UCS.

Restores the previous UCS.

The last 10 user coordinate systems created in model space and the last 10 created in paper space layouts are retained. Repeating this option steps back through one set or the other, depending on which space is current.

View

Aligns the XY plane of the user coordinate system to a plane perpendicular to your viewing direction. The origin point remains unchanged, but the X and Y axes become horizontal and vertical.

World

Sets the current user coordinate system to the world coordinate system (WCS).

The WCS is the basis for all user coordinate systems and cannot be redefined.

X, Y, Z

Rotates the current UCS about a specified axis.

Point your right thumb in the positive direction of the X axis and curl your fingers. Your fingers indicate the positive rotation direction about the axis.

Point your right thumb in the positive direction of the Y axis and curl your fingers. Your fingers indicate the positive rotation direction about the axis.

Point your right thumb in the positive direction of the Z axis and curl your fingers. Your fingers indicate the positive rotation direction about the axis.

You can define any UCS by specifying an origin and one or more rotations around the X, Y, or Z axis.

Z Axis

Aligns the user coordinate system to a specified positive Z axis.

The UCS origin is moved to the first point specified and its positive Z axis passes through the second point specified.

Object: Aligns the Z axis in the direction tangent to the endpoint nearest to where the object was selected. The positive Z axis points away from the object.