User Coordinate Systems

When you create entities in a drawing, they are located in relation to the drawing's underlying Cartesian coordinate system. The ELEVATION system variable specifies the distance from the xy-plane of the current coordinate system. If ELEVATION = 0 (zero), entities are created in the xy-plane of the current coordinate system.

Every drawing has a fixed coordinate system called the World Coordinate System (WCS).

You can also define arbitrary coordinate systems located anywhere in three-dimensional space. These are called user coordinate systems (UCS) and can be located anywhere in the WCS and oriented in any direction. You can create as many UCS as you want, saving or redefining them to help you construct three-dimensional entities. By defining a UCS within the WCS, you can simplify the creation of most three-dimensional entities into combinations of two-dimensional entities.

When you create a new drawing the WCS is the current coordinate system by default, which is indicated by the letter W in the UCS icon. When you display a drawing in plan view, you see the coordinate system icon from the top, with the z-axis directed straight toward you. When you display a three-dimensional drawing in a view other than plan view, the coordinate system icon changes to reflect your new viewpoint.

Note: You cannot delete or modify the WCS.

To help you keep your bearings in the current coordinate system, BricsCAD displays a coordinate system icon (UCS icon). The visible portions of the axes are the positive directions.

Three colors represent the three axes, making it easier for you to recognize the orientation in three-dimensional space:

• x-axis: red
• y-axis: green
• z-axis: blue 

The colors of the axes are controlled by the COLORX, COLORY and COLORZ system variables.

The Plan View command restores the Plan view or Top view of the current UCS or WCS.

The UCSICON settings variable controls the display and location of the UCS icon:

Show icon :

Controls whether the icon shows or not.

At origin :

Controls the location of the UCS icon: if on, the icon indicates the origin point of the current coordinate system (UCS or WCS). However, if the origin is not within the viewport borders, the UCS icon moves to the corner of the viewport, as defined by the UCSICONPOS (UCS Icon Position) settings variable.
When the at origin option is not checked, the icon always displays in the corner of the viewport defined by UCSICONPOS.

To move the origin of the current coordinate system

1. Type ucs at the command prompt.
   You are prompted: Specify origin of UCS or [Face/NAmed/Entity/Previous/View/X/Y/Z/Z Axis/Move/World] <World>:

2. Identify the new origin, then press Enter to confirm.

To define a User Coordinate System

1. Choose Drawing Explorer > Coordinate Systems in the Tools menu.
   The Drawing Explorer - Coordinate Systems dialog opens.

2. Click the New tool button () on the Drawing Explorer dialog.
   The BricsCAD Explore dialog closes.
   You are prompted: Current/Entity/Origin/View/X/Y/Z/ZAxis;3point;:;
   A prompt menu displays:

   

3. Press Enter to define the UCS using points.
   You are prompted: New origin <current origin>:

4. Specify the origin point of the UCS.
   You are prompted: Point of positive X axis <current point>:

5. Specify a point to define the positive X-axis.
   The command window reads: Point in X-Y plane with positive Y value <current point>:

6. Specify a point to define the positive Y-axis.
   The UCS is defined.
   The BricsCAD Explorer dialog reopens.

7. Click in the UCS Name field of the newly defined UCS to replace the <NewUCS> default name.

8. Close the BricsCAD Explorer dialog.

Command Options

See the EXPUCS and UCS commands.

To restore the WCS

1. Type UCS in the command bar, then press Enter.
   You are prompted: ?/3point/Delete/Entity/Origin/Previous/Restore/Save/View/X/Y/Z/Zaxis/<World>:
   A prompt menu displays.
2. Do one of the following:
3. Press Enter to accept the default option.
4. Choose World in the prompt menu.
5. Type W in the command bar and press Enter.

To restore a UCS 

1. Choose Drawing Explorer > Coordinate Systems in the Tools menu.
   The Drawing Explorer - Coordinate Systems dialog opens.
2. Click the blank tile in front of the UCS name to make it current.
3. Close the BricsCAD Explorer dialog.

Note: If no UCS is marked, the WCS is the current coordinate system.

To set a relative UCS

1. Do one of the following:
   • Click the UCS... tool button () on the Settings toolbar.
   • Choose UCS... in the Settings menu.

   The User Coordinate System dialog opens.

   

2. Choose one of the following:
   • Set the selected UCS relative to the Current UCS .
   • Set the selected UCS relative to the World coordinate system (WCS) .

3. (option) Enable the Change view to plan view of the selected UCS option.

4. Click one of the Planar UCS's buttons.
   The User Coordinate System dialog closes.

Command Options

See the SETUCS command.