So... I tried to find a solution.
And it seems that it's not an "Octane" problem, but more a Houdini modeling problem.

My rope was just a line (it sounds like the beginning of a pop song).

I added to it some thickness (with a "curve surface" node) to transform it from simple line, to thin round ...

Hello everybody,

I'm new here, and i hope i'll be clear to explain you my problem.
I made a moving flag on houdini. But now, i try to apply some material to it.
But what happen is my material is filling the hole between the moving rope/flag and my flagpole.

It worked with houdini/mantra material ...