Lossless Compression of Free-Form Curve and Surface in CAD Models

A new algorithm of lossless compression about free-form curve and surface in CAD models was proposed to effectively exchange and transmit the model data in collaborative design environment.In the algorithm,optimal linear prediction was realized by Minimum Mean Square Error,and then mantissa coding was introduced according to the character of floating-point values in IEEE standard.As a result,the control points’coordinates in free-form curve and surface were compressed in completely lossless manner.The algorithm avoids loss of precision and feature generated by traditional algorithm of polygon mesh approximate compression.Experimental results show that the algorithm presented here is effective for geometry compression.