中文摘要：

针对协同设计环境下三维CAD模型网络传输慢等技术瓶颈，提出了一种针对精确CAD模型中自由曲线曲面的无损编码压缩算法．该算法采用最佳线性预测，并结合IEEE标准单精度浮点型数据的表达特点，引入了尾数差值编码算法，对曲线曲面的控制点信息进行了预测编码无损压缩，避免了现有多边形网格逼近编码压缩算法造成的精度损失和特征信息丢失．实验结果表明：该算法具有良好的压缩效果．

英文摘要：

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.