在3dsmax中模拟全局照明
[font=黑体][size=3][color=black]'Faking Global Illumination in 3D Studio Max'－－在3dsmax中模拟全局照明[/color][/size][/font][font=黑体][size=3][color=black][b]'Faking Global Illumination in 3D Studio Max'[/b] [/color][/size][/font]
[font=黑体][size=3][color=black]by Lee Kellett
原文链接：[/color][/size][/font][url=http://www.3dtotal.com/team/Tutorials_3/faking_gi/faking_gi01.asp][font=黑体][size=3][color=black]http://www.3dtotal.com/team/Tutorials_3/faking_gi/faking_gi01.asp[/color][/size][/font][/url][font=黑体][size=3][color=black] [/color][/size][/font]
[font=黑体][size=3][color=black][img]http://www.3dtotal.com/team/Tutorials_3/faking_gi/images/main.jpg[/img][/color][/size][/font]
[font=黑体][size=3][color=black]Introduction: 、
（简介） [/color][/size][/font]
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Global illumination is normally seen in powerful rendering systems like V-Ray and also in recent versions of Mental-Ray. There are two types of Global illumination; these are Direct Illumination and Indirect Illumination. Direct Illumination takes into account the light rays from the light source and also the surface, and Indirect Illumination is where that light is reflected of one surface onto another. In 3Ds Max this can be achieved using Light Tracing rather than radiosity or third party rendering systems like V-Ray or without setting up Mental-Ray
（全局照明通常见于强力的渲染器如Vray，也存在于当前版本的mentalRay。全局照明包含两种类型的光照：直接光照和间接光照。直接照明考虑从光源来的光线，间接光照考虑从一个表面反射到另一个表面的光线。在3dsmax这可以通过使用光线追踪来实现，而不是光能传递或是第三方的渲染系统，如vray，也无需设置mentalray。）[/color][/size][/font] [font=黑体][size=3][color=black]Setup:
（灯光设置）[/color][/size][/font]
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The way I am going to set the scene up is as if I am going to render an exterior scene. I have a skylight that has Shadows enabled and I have decreased the Ray Per Sample to 5, the Ray Per Sample will decrease the quality when it comes to rendering but will speed up the rendering time as using Skylight are processor intensive. The second light I have setup is a Target Direct, it also has Shadows Enabled and also its shadow type is set to Ray Traced Shadows., under the Directional Parameters I have also changed the Falloff/Field so the light lights the whole scene.
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[font=黑体][size=3][color=black]（我将要设置场景的方式跟我要渲染一个完成的场景是一样的。我放了一盏天光灯，打开了阴影，将每光线采样值降到了5，这将降低渲染质量，但在计算天光时能提高渲染速度。第二盏灯我用的是目标平行光，同样打开了阴影，阴影类型为光线追踪阴影，在平行光属性下我调整了过渡场（Falloff/Field ），这样灯光能照亮整个场景。）[/color][/size][/font]
[font=黑体][size=3][color=black][img]http://www.3dtotal.com/team/Tutorials_3/faking_gi/images/01.jpg[/img] [img]http://www.3dtotal.com/team/Tutorials_3/faking_gi/images/02.jpg[/img][/color][/size][/font]
[font=黑体][size=3][color=black]If we do a quick render now you should get something that looks like this.
（如果我们现在做一个快速渲染，你能得到如下的结果。）
[img]http://www.3dtotal.com/team/Tutorials_3/faking_gi/images/03.jpg[/img]
As you can see all we have is a bright scene with sharp shadows.To make this look better we now want to add the Light Tracer.
（就像你看到的那样，我们得到了一个有着尖锐阴影的明亮场景。要做的更好一点，我们需要添加光线追踪引擎。）[/color][/size][/font] [font=黑体][size=3][color=black]渲染设置[/color][/size][/font]
[font=黑体][size=3][color=black]To add the Light Tracer go to Rendering > Advance Lighting > Light Tracer.
（展开菜单Rendering > Advance Lighting > Light Tracer添加光线追踪引擎。）
[img]http://www.3dtotal.com/team/Tutorials_3/faking_gi/images/04.jpg[/img][/color][/size][/font]
[font=黑体][size=3][color=black]This will bring up the Render, it should look like this. Make sure the type is set to Light Tracer and make sure the tick box is selected next to active. Set to Bounces to about 5 (the more bounces the lighter the shadow), if you wanted to increase the brightness of the light change to Global Multiplier but the default if normally ok also make sure the Sky Lights box is ticked if you are using Sky Light. (In this case we are) then click render and you should have something like this.
（这将提升渲染结果，渲染设置应该是这样的。确定高级照明的引擎为光线追踪引擎，并且勾选了激活选项。设置光线的反弹次数为5（反弹次数越高阴影越亮），如果你希望增强光线的亮度，可以调整全局强度（Global Multiplier ），但是如果正常的话保持默认值就好了。如果你使用了天光，那么要确保勾选了激活天光的小方框。按我们的情况，我们需要勾选这个方框，具体参数如下图所示。）
[img]http://www.3dtotal.com/team/Tutorials_3/faking_gi/images/05.jpg[/img][/color][/size][/font]
[font=黑体][size=3][color=black]As you can see the light has hit the object and has not only cast the shadows but has also reflected the red material on of the box to the floor surface, this is how light works in real life. By increasing the Bounces it will make the shadows brighter. The next thing to do after this is to change the Advance Lighting from Light Tracer from the dropdown back to No Lighting Plug-Ins and go back to the Skylight and change the Ray Per Sample back to 20 then Re Apply the Light Tracer and render. Changing the Ray Per Sample in the Skylight option back to 20 will get rid of the noise that appears when you was rendering although your renders will take a little more time to render now.
（正如你看到的，光线跟物体发生了碰撞，不仅投射了阴影，还将盒子上红色的材质反射到地面上，在真实世界里光线也是这样传播的。因为提高了光线反弹次数，使得阴影更亮了。下一步关闭高级照明，回到天光上，将每光线采样调回到20，然后重新应用光线追踪渲染引擎。将每光线采样调回20将消除出现的噪点，当然你的渲染将比刚才的要更耗时。）
[img]http://www.3dtotal.com/team/Tutorials_3/faking_gi/images/06.jpg[/img][/color][/size][/font]
[font=黑体][size=3][color=#000000]Apply these setting to a scene you are going create in the feature and see what you end up with.
（应用这些设置到你准备创建的场景中，然后看看效果如何。）
[img]http://www.3dtotal.com/team/Tutorials_3/faking_gi/images/07.jpg[/img]
来源：译文3D网
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