GI Portals and Polygon Lights: Function and Placement

GI 门户和多边形灯: 功能和布局

Improved quality with the application of GI Portals. Above a QMC rendering with 通过应用 GI 门户提高质量。在一个 QMC 渲染上面Diffuse Depth 漫射深度 set to 开始2. Double render time at top as opposed to GI portal with fewer . 双重渲染时间在顶部，而不是 GI 门户与较少Samples 样本.

Simply stated, Global Illumination is calculated based on randomly dispersed rays that are "beamed" at innumerable points in the scene to determine the brightness or color of each particular area. By nature, many rays will reach areas of a given point that are irrelevant to its illumination. It is much more important that a great number of rays are concentrated in areas at which light enters the scene, which makes the calculation of light and shadow much more precise.

简单地说，全局光源是根据随机分散的光线计算出来的，这些光线被“定向”在场景中的无数点上，以确定每个特定区域的亮度或颜色。从本质上讲，许多射线会到达给定点的与其照明无关的区域。更重要的是，大量的光线集中在光线进入场景的区域，这使得光线和阴影的计算更加精确。

The Rays are concentrated on the GI Portals and Polygon Lights ( 光线集中在胃肠道入口和多边形灯(Diffuse Depth 漫射深度 = 2).

Windows, lamps or other light-emitting objects (e.g., televisions) can be used as objects at which GI Portals or Polygon Lights can be placed in order to optimize GI calculation.

窗户、灯或其他发光物体(例如电视)可以作为物体，在这些物体上安装 GI 入口或多边形灯，以优化 GI 计算。

Hence, GI Portals and Polygon Lights are primarily effective when placed where light is emitted from smaller surfaces, as is most often the case indoors where light enters a room through a window or door. Portals are useless in conjunction with an outdoor sky illumination.

因此，GI 门和多边形灯主要是有效的时候，放置在较小的表面发射光线，因为最常见的情况是在室内，光线通过窗口或门进入房间。门户与室外天空的照明结合在一起是没有用的。

The different application areas of GI Portals and Polygon Lights:

GI 门户和多边形照明灯的不同应用领域:

GI Portals: Openings in walls through which light (e.g., from outdoors) enters the room. These Portals’ materials must have the GI 入口: 墙壁上的开口，光线(例如，从室外)通过这些开口进入房间。这些入口的材质必须具有Portal 入口option enabled ( 选项启用(Illumination 照明 material channel). 材质通道)
Polygon Lights: Objects that are designed to emit light (GI only), such as lamps. These objects (also called "Polygon Lights") contain a material with an active 多边形灯: 设计用来发光的物体(仅限 GI) ，例如灯。这些对象(也称为“多边形灯”)包含一个活跃的材质Luminance 亮度 channel and with the 通过这个渠道Polygon Light 多边形灯 option enabled. 启用选项

In the following instances additional rays will be beamed to the Portal or Area light. The number of rays that are beamed is defined using the Discrete Area Sampling or Discrete Sky Sampling option. Light maps also benefit if no further settings are available.

在下列情况下，额外的光线将被发射到传送门或区域光。定向光束的数量是使用离散区域采样或离散天空采样选项定义的。如果没有进一步的设置，光照贴图也会受益。

Tip: 提示:
In order for GI Portals to function, 为了使 GI 门户网站正常运行,Transparency 透明度 should NOT be deactivated in the Render Settings! 不应该在渲染设置中被停用

Portals and Polygon Lights are not necessary when rendering outdoor scenes in which the light primarily comes from a hemisphere-shaped sky.

当渲染光线主要来自半球形天空的室外场景时，门户和多边形灯是不必要的。

Tip 小贴士
Note that the use of GI Portals and Polygon Lights increases image quality with regard to light and shadow. This makes it possible to lower the common GI settings to achieve the same or better quality (fewer samples) and thereby reduce render times. 注意，GI 门户和多边形灯的使用增加了光和阴影方面的图像质量。这使得降低通用 GI 设置以获得相同或更好的质量(更少的样本)从而减少渲染时间成为可能

Where Should GI Portals be Placed?

胃肠道入口应该放在哪里？

Tip: 提示:
Due to changes in the algorithm (new in R12), we recommend creating 1 separate object for each GI Portal (instead of creating a GI Portal as an object with several non-adjacent polygons dispersed throughout the room (e.g., each window). Otherwise the render times will increase greatly. 由于算法的改变(R12新增) ，我们建议为每个 GI Portal 创建一个单独的对象(而不是创建一个 GI Portal 作为一个对象，其中有几个不相邻的多边形分散在房间中(例如，每个窗口)。否则渲染时间将大大增加

GI Portals should be placed/fitted at the windows. When placed at windows with a crossbar frame, multiple GI Portals will increase overall quality.

消化道入口应安装在窗户上。当用纵横条框架放置在窗口时，多个 GI 门户将提高整体质量。

GI Portals generally consist of single polygon surfaces (e.g., a Plane Primitive) that is placed at the location at which light enters the room through a relatively narrow opening. The direction in which the Normals face is irrelevant. Fit the shape of each GI Portal to match the corresponding window or opening. If a GI Portal is too large, e.g., if it stretches into a surrounding wall, artefacting can result (particularly noticeable in QMC mode). Imprecise GI Portals result in less accurate and "grainier" the GI.

GI 入口通常由单个多边形表面(例如，一个平面原语)组成，这些多边形表面放置在光线通过一个相对狭窄的开口进入房间的位置。法线面的方向是不相关的。调整每个 GI 门户的形状以匹配相应的窗口或开口。如果一个门户网站太大，例如，如果它延伸到周围的墙壁，人工制品可能会导致(尤其是在 QMC 模式下)。不精确的 GI 门户导致不准确和“颗粒化”的 GI。

Multiple GI Portals should be applied to windows with a crossbar frame (see above image) for more precise results. Applying a single GI Portal would cover the crossbars and therefore look less realistic.

应该将多个 GI 门户应用于带有纵横条框架的窗口(见上图) ，以获得更精确的结果。应用单一的 GI Portal 会覆盖交叉杆，因此看起来不那么真实。

On the other hand it would be overdoing it, for example, to assign individual GI Portals to each pane of a window with a honeycomb frame or a stained glass window. In such instances you should consider excluding such fine structures from the GI calculation (e.g., using the Compositing tag).

另一方面，这将是过分的，例如，分配个别 GI 门户到每个窗格的蜂巢框架或彩色玻璃窗口。在这种情况下，您应该考虑将这些精细结构排除在 GI 计算之外(例如，使用合成标记)。

Tip: 提示:
artefacting can occur in regions next to a GI Portal (e.g., a window frame). In such instances, moving the GI Portal farther behind the opening (e.g., farther to the outside when applied to a window) can prevent this from happening. 可以在 GI 门户(GI Portal)附近的区域(例如窗口框架)进行人工制品加工。在这种情况下，将 GI Portal 移动到开口后面更远的地方(例如，应用到窗口时移动到窗口外面)可以防止这种情况发生