A bidirectional curve network based sampling method for enhancing the performance in measuring ultra-precision freeform surfaces

► Traditional raster sampling method needs massive points for fully representing the measured ultraprecision freeform surface. ► A bidirectional curve network based sampling (BCNBS) method is developed to enhance the sampling efficiency. ► Two sets of curves are sampled along two different directions to form a network to represent the measured surface. ► Experimental results demonstrate the superior sampling efficiency of the BCNBS method over raster sampling method.