The offsetting of line and arc have been well discussed in many thesises, and many skilled methods were given, but very few forthe offSetting of the free curve.

• 平面直线、圆弧组成的线条族的等距放大问题已经在很多文献中给出比较完善的解决方案，技术相对比较成熟，而平面上自由曲线的等距放大问题却没有很好的解决方案。