The Riemannian metric of perspective in stereo graphic projection is introduced and a property of the continual cut vector field on the spherical surface is discussed. The accordance of the Riemannian metric with the flat metric of Euclid space is proved.

• 介绍了在球极投影下引入的黎曼度量,并介绍了这种度量的一些性质,指出了这种度量与从平直的欧几里德空间标准度量中诱导的黎曼度量是一致的;