DVD - 从上环走到中环

As 从上到下 means "from the higher level to the lower level", is "下" implied at the end of 从上环走到中环 (下) and insinuates that here the position of the periphery is higher than the position of the center ? (movie from Hong-Kong.)

Or does 环 just collocate with 上 ? "从上环走到中环" meaning "from the ring/periphery to the center (of the ring)" ?

Btw, 圆周 (yuánzhōu) circumference of a circle

and 周缘 (zhōuyuán) outer edge of a wheel