The surface texture of object can be classified as geometry texture and color-class texture.

物体表面纹理可分为颜色纹理和几何纹理两大类。

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The point of drawing white objects is that A. there is no color to confuse the issue, and B. it's really easy to see what the light does on the surface of a white object.

绘画白色物体的优点是：A。没有颜色问题要分心，B。很容易观察出光在白色物体上的表现。

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The color of certain object surface has a constant feature, irrelevant to the object surface shape. But the color of the image is variablebecause of the existence of highlights.

某种材料表面的颜色具有与形状无关的稳定特性，但图象中表面的颜色由于存在高光和影调而是变化的。

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