## Function

- UCS (User Coordinate System) converts the currently applied GCS (Global Coordinate System) into UCS.
- GCS converts the currently applied UCS into GCS.
- Assign a UCS from the sub-functions of Model > User Coordinate System. If UCS has not been assigned, the origin and axes of UCS are automatically set to coincide with GCS. Note that the point grid and line grid are always positioned on the UCS x-y (or GCS X-Y) plane.
- If a point grid or a line grid is specified to be displayed on the screen by the Point Grid or Line Grid function, it will move to the coordinate system's x-y plane (or X-Y plane) according to the UCS and GCS switching.
- The coordinate systems used in midas Civil are as follows:

**Global Coordinate System (GCS)****Element Coordinate System (ECS)****Node Local Coordinate System (NCS)**

- The GCS uses the X, Y, and Z-axes of the Conventional Cartesian Coordinate System with the right-hand rule. The axes are denoted by the capital letters (X, Y, Z). Nodal data and the majority of data entry related to nodes, nodal displacements, and nodal reactions are in GCS.
- The GCS is used for the geometric data for the structure. The Reference Point is automatically set to the coordinates X=0, Y=0, Z=0. In MIDAS/Civil, because the vertical direction of the screen is set parallel to the Z-direction of the global coordinate system, it is more convenient to coincide the vertical direction of the structure (the direction opposite to the direction of gravity) with the GCS Z-direction.
- The ECS uses the x, y, and z-axes of the Conventional Cartesian Coordinate System with the right-hand rule. The axes are denoted by the lowercase letters. (x, y, z)
- Element internal forces, stresses, and the majority of data entry related to elements are in ECS.
- NCS is used when boundary conditions such as constraints, boundary springs, or enforced displacements need to be specified in an arbitrary direction that does not coincide with the global coordinate system at a node, or when the reaction force in an arbitrary direction needs to be calculated and output. The axes are denoted by the notations x, y & z. Once the Node Local Axes define the node coordinates, the following boundary conditions and enforced displacements are entered according to the defined node coordinates:

**Supports**

**Point Spring Supports**

**General Spring Supports**

**Surface Spring Supports**

**Specified Displacements of Supports**

## Call

From the main menu, select **[View] tab > [Coordinate System] group > [GCS/UCS] > [GCS]**

From the main menu, select **[View] tab > [Coordinate System] group > [GCS/UCS] > [UCS]**