Ambient Occlusion

环境遮挡

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Ambient Occlusion

环境遮挡

Ambient Occlusion is a technique used to calculate how exposed a given sample point is to an imaginary ambient light source surrounding the entire scene. This effect is commonly used to approximate the diffuse lighting coming from an overcast sky, or to enhance contact shadows in interior renderings.In this example, Ambient Occlusion automatically measures the indentations in the surface and makes the material luminous .

Ambient Occlusion calculates a value whose brightness is dependent on the occlusion by surfaces and objects in close proximity. The greater the distance between neighboring surfaces, the brighter the AO calculation will be for a given pixel. Areas that lie in gaps or between objects will on the other hand have darker values applied. The effect is similar to a shadow, however it does not take any lights in the scene into account. The only deciding factor is the distance between the currently calculated point and neighboring surfaces.

环境遮挡计算一个值，其亮度取决于遮挡的表面和物体在接近。相邻表面之间的距离越大，对于给定的像素，AO 计算得到的结果就越明显。另一方面，位于间隙或物体之间的区域将应用较暗的值。效果类似于阴影，但是它没有考虑到场景中的任何灯光。唯一的决定因素是当前计算点与邻近曲面之间的距离。

The sampling direction can also be inverted, whereby. rays will be traced in the opposite direction of the surface normal. This produces a darkening effect in edges and corners, whereas flat or slightly bent surfaces remain light. By inverting via an Invert Color Node, simple Subsurface Scattering effects can also be approximated.

取样方向也可以反转，即。光线会沿着与表面法线方向相反的方向追踪。这会在边缘和角落产生暗化效果，而平坦或稍微弯曲的表面保持光亮。通过倒置的颜色节点，简单的次表面散射效果也可以近似。