To Create a Curve from a Surface
1. Click 
Style > > 
Curve from Surface. The Curve from Surface tab opens.
Style > > Curve from Surface. The Curve from Surface tab opens.2. Select a curve type:
◦ 
Free Curve
Free Curve◦ 
Curve on Surface
Curve on Surface◦ Isoline
Isoline3. To select a location for the curve, perform one of the following actions:
◦ Click a point on the surface for the curve to pass through.
◦ Click the References tab, click the Surface collector, select a surface, and then click a point on the surface.
A curve from surface with a default orientation is created.
4. To switch the curve direction, perform one of the following actions:
◦ Click 
.
.◦ Hold down the CTRL key while you click the surface.
◦ Right-click and choose Flip.
5. To move the curve along the surface, drag the curve, or type a value from 0 to 1 in the Value box. Optionally, click 
to export the parameter value to edit outside of Style.
to export the parameter value to edit outside of Style.6. Click 
OK.
OK.7. If needed, convert a curve from a surface to another curve type by selecting the curve and performing one of these actions:
◦ Click > > .
◦ Right-click and choose Convert.