Light and Form, Part 3
作者：James Gurney
翻译：DylanZhang（http://blog.sina.com.cn/ts152154539）


In soft or diffuse light, such as overcast light, there is no distinct light side, shadow side, terminator, or core. All of the upward facing planes tend to be lighter, since they receive more of the diffused light from the cloudy ceiling.
在柔光或者漫射光下，比如多云的阴天里，就没有明显的亮部，暗部，明暗交界线和那个core（具体解释见第二篇）。由于接收更多多云环境里的漫射光，所有朝上的面显得更亮。


The photograph of the ball shows the quality of overcast light. The cast shadow has no definite edge. There’s no clear division between light and shadow unless the form turns on a hard edge.
照片显示了阴天环境下的球体表面情况。投影没有明确的边。在亮部和暗部间没有明确的分界，除非这个形体是以硬边转折的。


Here’s an example of overcast light falling on the figure of David Balfour in the N. C. Wyeth illustration “On the Island of Earraid,” from Kidnapped. The planes of the figure’s skin and clothing get lighter where they face more toward the light sky. (The sharp tonal changes in the background are dramatic plane changes in the rock.)
这是N. C. Wyeth插画中的一个画面，里面的主人公David就身处阴天的光环境下。人物的皮肤和衣服更朝天空的地方显得亮一点。（背景中那块大岩石调子的剧烈变化是因为那个面转折很强烈）。


Another example of overcast light is this portrait of a girl by William Bouguereau. The form doesn’t have a light side and a shadow side in the conventional sense. The vertical plane of the dress and the upper arm are both darker than the forearm and the leg of the dress, which catch more light because they face more upward.
另一个例子就是William Bouguereau的女孩画像。画中人物形体没有传统感觉里的亮部和暗部。裙子的竖直面和上臂都比前臂和大腿那个面显得暗，因为前臂和包裹大腿的裙子面朝上吸收更多的光。

The coolness of this light source is evident from the relatively warm shadow under the chair. Occlusion shadows require especially careful attention in diffuse light, often appearing as notably sharp accents in the work of Bouguereau and Rockwell.
光源的冷色与椅子下暖色的影子相比很明显。在漫射光中，需要更加注意occlusion shadow（另一篇讲occlusion shadow的文章中有详解），在Bouguereau 和 Rockwell的作品中，这个occlusion shadow通常以一个明显的急转的调子出现。