1. A method of tessellating a parametric patch of an object, said method comprising: vectorising a boundary curve associated with the parametric patch according to a pre-determined flatness tolerance; determining a tessellation point associated with a first parametric value inside the parametric patch based on geometry of the parametric patch and a tessellation step; determining a curve associated with the first parametric value based on the geometry of the parametric patch and the tessellation step; determining a colour split point on the vectorised boundary curve, the colour split point being determined based on the vectorised boundary curve and the determined curve associated with the first parametric value; and tessellating the parametric patch by joining the colour split point and the tessellation point.