试译：灯光通常情况下应该是漫射的,但(所形成的)照射方向却足以使羊毛分选工能够从各个角度全面细致地观察他的样品.
direction在文中是指（光的传播、照射）方向.
perception of depth 深度知觉,在本句中, allow perception of depth如果直译成"使...具有深度知觉"则显得很生硬,不妨灵活译成“使...可以全方位地(察看)”或“全面地(察看)”.
与此相对应的的sensation of depth深度感觉（动物具有深度感觉,人在此基础上具有更高级的perception of depth深度知觉）
英英词典对depth perception的解释为：
Depth perception
Depth perception is the visual ability to perceive the world in three dimensions (3D) and the distance of an object. Depth sensation is the corresponding term for animals, since although it is known that animals can sense the distance of an object (because of their ability to move accurately, or to respond consistently, according to that distance), it is not known whether they "perceive" it in the same subjective way that humans do.
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