How to remove abnormal points?

Hi,

I have a 2D curve and try to create 2 bands around it (is it called envelope curve?), then use Qt to plot them, as shown in the attached screen capture.

The problem is that the bands are cross over at many places. Is there a way to remove those unwanted effect?

I try to use QPolygonF::united( ... ) to remove the effect, but it is way too slow (over 60 seconds).

Any better and fast way to deal this?

Many thanks...

Anyone please?

Since this is unrelated to Qt you might have better luck in some forum that specializes in geometric algorithms.

Cheers,
_