And if there are multiple light sources, why does each object only cast one shadow?

而且如果说有多个光源的话，为什么每个物体只有一个影子呢？

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The qualities of a shadow depend on the light direction and intensity, as well as the distance between the object and the surface where the shadow is cast.

阴影深度取决于光照方向和强度，以及物体和投影面的距离。

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When light from a single direction (e.g. our sun) hits an object, part of the object is in shadow.

当单一光源例如太阳照到某个物体上，物体的一部分会处于阴影中。

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With red and white light, the shadow of the object appears in the complementary color -- cyan -- and the shadows change as your angle of vision changes.

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Making use of seven shooters simultaneously, the system photographs the object while projecting various light and shadow combinations in order to determine the ware's geometry.

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