In order to guarantee the quality of surface finish machining and reduce the work volume in the subsequent processes,the paper proposes an error-controllable direct interpolation algorithm of projective curves on sculptured surfaces.

The projection curve analysis when a plane cuts off a circular cone with an ellipse section line at an oblique angle;

The brightness information and the projection curve of the reflect image from the fabric surface are used to confirm the position of the yarn clearances in the processed imag.