The different kinds of direct and indirect light
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· In the left picture you can see several effects, that direct or indirect light can cause on an objects surface: Highlights (1 & 2) - these effects are mainly caused by direct light (the big red arrow). There are two types: the »phong« (1) and the »specular«-highlight (2). As you can see, specular-highlights occur more in the vicinity of an objects horizon. Diffuse reflection (3) - when a light beam hits an object it is reflected. On a perfectly plain surface a light-beam leaves the surface at the same angle it came in. Due to roughness or bumpyness, the reflected light is scattered in all directions, causing »diffuse«-reflection. Ambient light (4) - not only the sphere in this picture reflects light - every object does! Because of this habit, there is always a certain amount of background-light in a room. This background-light causes the so called »ambient«-illumination. Specular reflection (5) - unlike the »diffuse« reflection, the »specular reflection« does not scatter the light, so that a more or less clear picture of the surrounding objects is mirrored on the objects surface.
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