## Function

- Define the User Coordinate System.
- Most structures in practice are composed of a combination of many different plane frames and modules of similar geometric characteristics. Each plane frame and modular unit can be singled out in a given coordinate system apart from the Global Coordinate System. This local coordinate system is conveniently selected to simplify the process of geometry generation.
- The User Coordinate System is referred to as the coordinate system set up by the user to ease the modeling task.
- In addition, the use of the UCS x-y plane in conjunction with the use of grids to place the grid points of grid lines provides an effective modeling environment.

## Call

From the main menu, select **[View] > [Coordinate System] > [Define UCS]**

## Input

Select a desired tab in the dialog box and enter the related data.

### Activate UCS Plane

Activate the UCS x-y plane including the UCS origin point. Use Active All to activate the remaining parts of the model.

### Change View Direction

Automatically change the View Point to view the model from the UCS (+)z-direction.

### X-Y Plane

Set the UCS x-y plane to be parallel with the GCS (Global Coordinate System) X-Y plane.

**Origin**

Enter the coordinates of the UCS origin point with respect to the GCS.

Rather than typing in the coordinates, click the entry field and the relevant position in the working window.

**Angle**

When the UCS x-y axes are rotated about the GCS Z-axis, enter the rotation angle with an appropriate sign using the right-hand rule.

Fig. X-Y Plane Dialog Box

### X-Z Plane

Set the UCS x-y plane to be parallel with the GCS X-Z plane.

**Origin**

Enter the coordinates of the UCS origin point with respect to the GCS.

Rather than typing in the coordinates, click the entry field and the relevant position in the working window.

**Angle**

When the UCS x-y plane axes are rotated about the GCS negative Y-axis, enter the rotation angle with an appropriate sign using the right-hand rule.

Fig. X-Z Plane Dialog Box

### Y-Z Plane

Set the UCS x-y plane to be parallel with the GCS Y-Z plane.

**Origin**

Enter the coordinates of the UCS origin point with respect to the GCS.

Rather than typing in the coordinates, click the entry field and the relevant position in the working window.

**Angle**

When the UCS x-y axes are rotated about the GCS X-axis, enter the rotation angle with an appropriate sign using the right-hand rule.

Fig. Y-Z Plane Dialog Box

### Three Points

Enter the coordinates of the UCS origin point and the coordinates of 2 points on the UCS x-y plane to define the UCS.

**Origin**

Enter the coordinates of the UCS origin point with respect to the GCS.

**Pt. on x-Axis**

Enter the coordinates of a point on the UCS x-axis.

**Pt. on x-y**

Enter the coordinates of a point on the UCS x-y plane.

Fig. Three Points Dialog Box

### Three Angles

Enter the coordinates of the UCS origin point and 3 angles to define the UCS.

**Origin**

Enter the coordinates of the UCS origin point with respect to the GCS.

**Step1. About X Axis** : Angle of rotation about the GCS X-axis.

**Step2. About y' Axis** : Angle of rotation about y'-axis, which is modified by step1.

**Step3. About z'' Axis** : Angle of rotation about the z''-axis, which is modified by steps 1 & 2.

Fig. Three Angles Dialog Box

Step 1. Angle of rotation about the GCS X-axis.

Step 2. Rotation about the modified y'-axis by AY angle (y'-axis defined by step 1)

Step 3. Rotation about the modified z''-axis by AZ angle

Fig. Definition of UCS (Three Angles)

### Named Plane

Define the UCS x-y plane by selecting a plane defined by Model > Named Plane.

Fig. Named Plane Dialog Box

### UCS by UCS

Define the UCS by modifying the currently defined UCS.

Fig. UCS by UCS Dialogue

**x Rot** : Angle of rotation about the current UCS x-axis

**y Rot** : Angle of rotation about the current UCS y-axis

**z Rot** : Angle of rotation about the current UCS z-axis

**Origin Point** : Coordinates of the new UCS origin point relative to the current UCS

### Named UCS

Access and apply a UCS previously saved.

To save the current UCS click **Save Current UCS** at the bottom of the dialog box

**UCS Name**

Name of saved UCS

**Origin Point**

Origin coordinates of the new UCS (in GCS)

**ux** : Direction vector of the new UCS in x-dir. (in GCS)

**uy** : Direction vector of the new UCS in y-dir. (in GCS)