extract the outer surface of the tube and show it as a rectangular surface

[roland]

Hi @mohsen.rock,

In this post I explain my steps whenever I need to unwrap cylinder. Maybe it is of use to you too.

Unwrapping a cylinder

Can it be that your surface is folded back on it self because you use an atan function instead of atan2? I don’t know if atan2 is available now, but it wasn’t before, so I used to calculate it myself with a Calculator filter: if(coordsX>0,atan(coordsY/coordsX), if(coordsX<0, if(coordsY<0,atan(coordsY/coordsX)-4*atan(1),atan(coordsY/coordsX) +4 *atan(1)), if(coordsY>0, 2 *atan(1), if(coordsY<0, -2 *atan(1),0)))) Then apply a [-pi, pi] threshold on the resulting angle (which I called theta). …

Kind regards,
Roland