# CONVTONURBS [GstarCAD 2021](Help%20System/GSTARCAD/2021/Index.md) → [What's new](Help%20System/GSTARCAD/2021/What's%20new/(What's%20new).md) You can input CONVTONURBS command or click Ribbon- Surface – Convert to NURBS to convert solidsand procedural surfaces to NURBS surfaces.You can also convert meshes to NURBS surfaces after converting them to a solid or surface by CONVTOSOLID or CONVTOSURFACE command.  There are a series of new functionalities for NURBS control vertices editing and display, such as **SHOW CV**: Shows control vertices.You can adjust the NURBS surfaces by clicking the control vertices, you will get 4 options (Base, Copy, Undo, Exit) in your command line and dynamic input box. **Base:** Moves your control vertices according to the base point and second point you choose. **Copy:** Copies a new NURBS surface and move it, the original surface won’t be deleted. **Undo:** Cancels the previous step. **Exit:** Stops adjusting control vertices. **HIDE CV**: Hides control vertices. **ADD**: Adds control vertices. After selecting the object, you will get 2 options (Knots,Direction) to add control vertices and set the position. **Knots:**Turns off the display of control vertices and allows you to place a point directly on a surface. This option only displays if you select a surface; it does not display for splines. **Direction:**Specifies whether to add control vertices in the U or V direction. This option only displays if you select a surface; it does not display for splines. **REMOVE**: Removes control vertices. **DELOBJ** :System Variable, when sets the value to 0, the defining objectswon’t be deleted, when the value is -3, there will be a two options for users to choose delete or not, when it is 3, the defining objects will be deleted. --- Gstarsoft Co.,Ltd