How to get the point of intersection with isoparametric curve and Geom_Surface ?

Hello together, I'm rgw.

I want to get the point of intersection with isoparametric curve and Geom_Surface.

I created an isoparametric curve on a surface and use it to intersect with the surface.

Now I want to know the intersections of a certain isoparametric curve (yellow curves) and the surface.

The intersection result i think is two points and one segment. Take one "long" isoparametric curve for example(schematic diagram1), it intersects the edge twice and the intersection points should be where as shown below.(schematic diagram2.png)

First I use UIso to get the isoparametric curve. Then I use GeomAPI_IntCS to get the intersection result.

But the result I got only has many points and the result as shown below. (result.png)

Any hints, suggestions, corrections, help? Thanks very much!