Actually real-world features are never infinitely sharp, especially for mechanical parts whose sharp features are often changed into fillets. The features similar to these fillets are called semi-sharp features. 实际上,所有物体的特征都不会是无限尖锐的,尤其对于机械零件来说,其尖锐边更多的会用圆角过渡,本文称这种类似于圆角的特征为半尖锐特征。