The surface of tub is not good

I noticed that the surface of cilinder is not well (it is rough and has this angles, image is attached). But I need to create very accurate surface of the cilinder with diameter of 4 m to make substraction. How can i do it? Or is it just due to visualization driver?Untitled|690x391

What you see is an effect of visualisation, where for representation, surfaces are approximated by polyhedral meshes. At tracking, precision is assured at the level of geometrical accuracy (down to 1E-9*mm)…

Thank you for information!