You can create an Exclude Collide Pairs constraint for nCloths, passive objects, or vertices to prevent them from colliding with specific nCloths, passive objects, or vertices. This constraints is useful when you want to improve the performance of your nCloth or you want to avoid collision geometry crossovers.
To create an Exclude Collide Pairs constraint
If you selected two nCloth objects, they no longer collide. If you selected an nCloth object and a passive object, they no longer collide. If you selected a group of vertices from one nCloth, and then another group of vertices from a different nCloth, then the vertices you selected no longer collide.
See also nConstraint menu.