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2011-05-13 21:17:24
What do I know about lighting after all?
我究竟是怎么认识灯光的呢？
After my previous post on
setting up a three layer SSS shader, a few people asked for tips on how
to light their characters to best show them off.
在我发表了如果建立一个三层的sss着色器后，有几个人问我关于如果用灯光来更好的表现它们的角色。
As it happens, this
something I’m rather interested in, and I’ve had a blog post on the
subject brewing for a while, so I’ve finally found the motivation to
finally write it up.
当这发生后，我对这个相当感兴趣。于有我想在blog里发表一个专题，并且最后完成了它。
I didn’t want to spend too much time talking about specific settings for this tutorial, so instead you can download this from BlendSwap.com for some ideas on the specifics of how to set up your scene.
我并不想花太多的时间讲如何做一些特殊的设定，不过你可以从blendswap.com里下载到相应的blendfile,那里会有一些关于如何设定你的场景的特定的主意。
Lighting in portraits is key to how you want your character to be
seen.
在肖像里的灯光就是对于如何表现你的角色的一个很关键的因素。
The exact same character with the same pose and expression can be
seen in completely different ways depending on how they are lit.
不同的灯光可以使完全相同的角色表现得非常不同。
They can be made to appear anything from dark and sinister to calm and serene simply by changing the lighting of your scene.
只要改变你的场景的灯光，就可以将任何东西从灰暗，阴险变成平静，安详。
On a more subtle level different kinds of lighting will can drastically improve the look of your models, and transform them from drab and uninteresting to dynamic and captivating.
只要很微小的改变就能很大的提高你的模型，并将其从单调，无趣变成动感，有魅力。
I don’t get it right every time, so when I’m looking for inspiration
for lighting I usually turn to those who know better.
我不会总是正确的，所以我从大师那里寻找灵感。
From the great painters and photographers, to Hollywood Films, to modern day CG artists, each can offer insights into what makes for interesting lighting.
从伟大的画家，摄影师，好莱坞电影，现在CG艺术家那里，能学到很多东西。
Three Point Lighting:
三点光
Before delving into some deeper issues, let’s look at what is
considered the “standard” lighting setup for a lot of portraiture and
cinematography.
在更深入的探讨之前，我们先看一下被认为是 照亮了无数肖像与电影的标准。
Three point lighting is the use of three different lights to achieve a pleasant, natural look that is adaptable to a wide variety of circumstances, and gives good results with most subjects when set up correctly.
三点光是用三个不同的光源来取得一种舒适的，自然的外观。这种方式被应用得非常广泛。而且只要设定得当，效果相当不错。
Conrad Veidt as Major Strasser in Casablanca
康拉德·维德特 在卡萨布兰卡中的少校。
You should be able to see that the main source of light in the image above is coming from slightly above and to the side of the shot.
你能分辨出上面的图像的主光源是从光照的侧面的稍上一些。
This is called the “key” light. This provides illumination to most of the face, but were we to only have that one light in the scene, the remainder of the face would be in shadow.
这个被叫做“key”,它提供了脸部的大部照明，当然如果只在场景中有这样一个光，其它没有照到的部分就会在阴影晨。
For the whole face to be seen we add a second, slightly softer “fill” light from the other side, at roughly eye level.
考虑到整个脸，我们加了第二个灯，补光灯，在另一面但是更加柔合。
This gives an even illumination to the shadowed parts of the face. A third “back” light (also called a “rim” light) light, positioned behind the subject, is used to highlight the edges of the subject and lift it out of the background.
不过第二个补光会对阴影部分有一个奇怪的照明。所以第三个 后边缘光 应该放到物体的后边，来打亮主休的边缘，这样就能把它放到背景里了。
A basic three point lighting setup.
最基本的三点光设置。
This kind of lighting is easy to do in blender, and is best done using either spot lights or area lights, as these give a good amount of control over the direction and placement of the light, and also have some of the best tools for adjusting the softness of the shadows.
这种光是容易在blender中实现的，无论是用spot还是用area， 因为它们都能控制方向，位置，光的强度及投影。
Spot
lights are preferable for animation, as using buffered shadows allows
objects in the scene to cast shadows over each other without resorting
to ray-tracing (which would increase render time significantly).
spot比较适合于动画，应用缓存投影会让物体做出相互的投影而不用光线追踪。这样能很大的提高速度。
Area lights give much nicer soft shadows, but at the cost of much longer render times.
area能给出一个更完美的柔各投影，但是要多花些渲染的时间。
Spot Lamps with buffered shadows vs. Area Lamps with ray traced Shadows. Rendertimes in Blender 2.5 (with raytraced AO for both) - Spot Lights: 28 seconds. Area Lights: 2 mins 59 seconds.
上面就是一个spot+缓存投影与area+光线跟踪的对比。
实际结果：blender 2.5，两者都应用了AO
spot 28秒。
area: 2分59秒。
Hollywood!
Three point lighting is a familiar feature of any film, CG animation or photographers studio today.
现在三点光是经常用在电影，CG动画，摄影室的。
Originally though, it became popular in the golden era of Hollywood, when film makers wanted to make sure that their sets and actors were evenly illuminated so that movie-goers could see all the money they spent on their productions.
最开始，它是在好莱坞黄金时期开始变得流行的，目的就是为了让观众看到所有制片人花在设施与演员身上的钱。
Because early colour
film didn’t capture contrast between light and dark very well, Directors
often used bright key and fill lights that gave very even illumination
the actors on screen.
因为早期的电影不能很好的捕捉出明暗的对比，导演通常用主光与补光把屏幕上的演员表现得很奇怪。
Think back to those early technicolor films for examples:
比如像下面的早期电影。
Marilyn Munroe in The Seven Year Itch
七年之痒中的梦露。
This kind of lighting doesn’t have any particularly dramatic qualities, but it does an excellent job of showing everything that is going on in shot.
这种光没有带来任何特殊的效果，不过却很好的表现出了这个镜头中的所有东西。
It also shows off texture well (look at the
wooden siding in the picture above for example), and looks very natural.
而且对于纹理表现得也很不错，看起来很自然（看看边上的木纹）。
Getting this kind of lighting using a three point setup in blender is as simple as setting the fill and key lights to reasonably high intensities and long fall off distances, without much difference in brightness between the two.
在blender中设这种光还是很简单的，只要设定主光，补光在一个合理的高度，衰弱长度，不用太考虑两者在亮度上的不同。
The back light used in this kind of lighting is reasonably subtle and diffuse, so set the intensity of your back light reasonably low and use fairly soft shadows.
后边的光就比较微妙而且发散， 所以把它弄得暗一些，投影柔和一些。
High-key Lighting
主光。
Rembrandt:
伦勃朗：
Let’s jump back in time for a second to the the seventeenth century.
我们再回到17世纪。
In Holland at the time, a revolution was occurring in how artists
treated light.
在那个时期的荷兰发生了一场艺术家如何用光的革命。
By this point in time much of the physics of light was
understood and was being applied to the art of painting, but the Dutch
masters – in particular Rembrandt – started a revolution in the use of
light for the exposition of drama and storytelling in their scenes.
这时，很多的物理光已经被了解而且应用在绘画艺术上，但是荷兰的大师，特别是伦勃朗，开始了一场在场景中戏剧与故事表现的用光革命。
By
thowing light on the elements in the scene they wanted to draw attention
to, and throwing elements that were less important into shadow painters
could control how people interpreted the scene.
通过投光到主要元素，把次要元素放到阴影中的方法，画家能控制人们如何解决场景。
This more dynamic style of lighting was also popular in portraiture, particularly because as well as adding plenty of dramatic flair to the image, it also breathed life into the forms of the subject, highligting those that face the light and veiling those that turn away in shadow. T
这种动态风格的光照在肖像画上也很流行，特别是增加了很戏剧性的东西，它可以让主题在形式上更生动，突出那些光照的脸，遮住那些在阴影中的脸。
his created a lot more visual interest when compared with the more diffuse, flat lighting of a lot of Renaissance art.
他比那些在文艺复兴中所用的散射，单调的光线，能创造更多的视觉上的兴趣。
The Night Watch by Rembrandt.
伦勃朗看到的晚上。
One of his most well known paintings, and a famous example of the use of light to highlight the dramatic elements of the composition.
这是一幅他的非常著名的画作，而且 是一个很好的用光突出构图主题的例子。
Returning to Hollywood, this kind of lighting rose to prominence first in German Expressionist Cinema and then in the Film Noir era as directors sought to portray their actors in more dynamic ways. It has been popular ever since.
回到好莱坞，这种首先用在导演用于表现黑帮时代中的演员。从那以后变得非常流行。
Marlon Brando in The Godfather.
马龙白兰度在教父中。
Note the triangle of light under the eye on
the shadowed side of the face.
注意一下投影侧的眼下的三角形的光照。
This is referred to a as Rembrandt
lighting, as it was a common motif in Rembrandts works.
这个指的就是一个伦勃朗光，这个就是伦勃朗工作中通常的用法。
Gordon Willis, the cinematographer on The Godfather, specifically cites Rembrandt amongst his influences for the film.
教父的摄影师，在这部电影中特别引用了伦勃朗的方法。
In cinematography this is referred to as low key lighting, and
can be achieved through our standard three point light set up once
again.
在电影摄影中这个叫低关键光，这个可以通过重设我们的三点光来得到这种效果。
This time, our key light is much brighter than the fill light (turn the “energy” setting up on the key light), and should have much more pronounced shadows as a result, we can also decrease the size of the lamp (the “size” setting for area lamps, or “soft size” for spot lamps) to make give our shadows much clearer outlines.
这时，我们的主光就应该比补光更亮些（把主光的energy设得多点），做为结果，要弄出更多的阴影。我们也可以减少灯的大小（对于area,是size这个设定，对于spot是soft size）来产生更清晰的外边缘。
Low-key Lighting：低主光。
This kind of lighting is ideal for showing off character models,
as it higlights the forms and makes them appear much more three
dimensional, compared to flatter, high-key lighting.
这种类型的光照用于展示角色模型是比较理想的，因为它能突出外形，并且比起高主光能让它们在三维上表现得更好
However, by playing up the forms and increasing the contrast, it may make your textures less prominent – something you may want to consider if you spent hours slaving away over a multi-layer SSS shader with detailed textures!
不过，这种形式加上提高对比度，会让你的纹理不太突出。 有时你得考虑一下，尤其是你花了大量的时间，精力在纹理的细节上。
Rim Light
边缘光
Up to this point I have largely neglected the third light in our
three point setup.
到现在为止我一直忽略着边缘光。
Unlike the other two it’s primary purpose is not to
provide illumination to any large area of the subject.
不像其它两个，边缘光的目的不是去提供对任何区域的照明。
Indeed, being
positioned behind the subject this would be impossible.
当然了，放到物体的后边，这也是不可能的。
Instead this
light is used to pick out the outlines of the the subject and thus
separate it from the background.
边缘光就是为了突出主题的边缘，并且它把从背景中分离出来。
Rim lights can be very useful in darker
scenes where the subject might otherwise fade into the background (of
course this may well be the effect you desire, in which case carry on).
边缘光在暗黑的场景，主题融入到背景中是非常有效的（当然它也许就是你想要的）。
Rim light is also quite dramatic, and works well in both high and low key lighting.
边缘光也是非常引人注目的，并且可能在高低主光两种情况下工作得非常好。
Brad Pitt as Tyler Durden in Fight Club.
皮特，在搏击俱乐部
Much of the film was set in dark, gritty environments, and the use of back lights helped the characters "pop" out of the backgrounds, without requiring bright frontal lighting.
这部电影中通常是在一个黑暗，粗糙的环境下，而背光的运用把角色从背景中拉了出来（这不要太多的正面的照明），
I find getting rim lights to give the effect I want in blender is often the most tricky aspect of lighting characters, as searching for the right balance between illuminating the outline, and not spreading out too far over the subject, requires a fair amount of trial and error for the placement of the lamp.
我发现设置边缘光来做出我想要的效果是最费劲的事，因为要平衡照明，边缘等，要花大量的试验，错误去设置灯.
Additionally, because the we only see the effects of rim lights at angles that are just glancing off the surface, rim lights must be quite bright in comparison to the main key and fill lights in order to stand out (usually several times brighter, though again this requires experimentation).
另外，因为我们只能看到被边缘光照到的角，边缘光就要比主光更亮，通常要几倍的亮度。
Lit mainly from behind with a large, bright, area lamp, with the shadow samples turned up to 16.
像上面这个从后边照过来的大面积的area灯，阴影采样设到了16.
Depending on the kind of illumination you want, rim lights may not require raytraced/buffered shadows at all, instead relying only on the angle the light hits the surface.
边缘光可能不需要光线跟踪与缓存阴影，如果考虑到你要的效果。只要用调整光照亮物体表面的角度就成了。
As such the effect of rim lights can also be faked using material nodes.
有时这种效果可以用材质结点来虚拟出来。
A
similar look can be achieved with out a back light.This time a ramp is
shader used to give the same effect instead.
这个类似的外观效果可以不用任何背光就能取得，这个是用着色器来做的。
This is much faster, but doesn't give quite the same quality.
虽然很快，不过质量上是不同的。
Colour
颜色
Colour theory is of course an entire subject in itself.
颜色理论本身就是一个完整的主题。
I shall mention it only briefly here in so far as to say that opposition between the two main lights (fill and key) can create some really nice effects.
我这里只是大概的提一下在谈到主要光源（主光与补光）用到的，能创建一个比较好的效果。
Opposing colours of course are those on either side of a colour wheel:
对等光通常就是指色轮上的相对的。
In general opposing colours look good when paired with one another.
通常对等光配对使用，会看上去不错。
Another consideration when thinking about colour choices is how they interact with the subject.
另外还要考虑到选择的光是如何在主题上相互影响的。
Skin is a sort of pinkish-orange colour, and so warm tones like reds and oranges complement it well, the opposing colour to these tones are bluey-green tones, and these also work well, particularly as fill or rim lights.
皮肤是一种粉红略带橙色的，所以暖色调像红色或是桔色做补充就不错，相应的对比色是那些兰，绿色调。特别是用来做补光或是边缘光是相当不错。
You will note for most of this tutorial I have opted for a key light with slightly orange tint, and fill and rim lights with a blue colour.
你可以看出来这个教程中我选的主光通常都有点略显橙色，而补光，边缘光有带些蓝色。
Complementary Colours often work well for the fill and key lights, though not all combinations work well when lighting skin tones.
做为补光或是主光的补充光通常工作的不错，但是不是所有的组合都很好。
The green light on the right would give the skin a very unhealthy look.
最右边的绿色就给皮肤一种非常不健康的感觉。
Light Direction and Character
光线方向与角色。
Within any lighting setup, the predominant direction the character is
lit from communicates a lot about the character.
在灯光设定是，最能影响角色的是显露角色多少。
We are used to seeing people lit by natural light, and so we often find that characters lit from strange angles appear more visually arresting, and often unsettling.
我们通常看到的人是在自然光线照明下的，所以我们通常很容易发被奇怪光线照射着的角色显得很刺眼很不安。
Achieving this in blender is a simple matter of positioning the key light to provide light from the desired direction, and having the fill light take an opposing position to provide illumination of the shadowed areas.
要达到这点，只要简单的放置主光从想要的方向照过来，将补光放到对面来提供对阴影区域的照明就可以了。
Lighting from above makes characters look dignified and noble,
从上而来的光显得角色看上去庄严，高贵
from below makes them look sinister and menacing.
从下就阴险，邪恶。
Lighting from behind gives a mysterious outline.
从边上就很神密。
Many famous pieces of devotional art use lighting from above to denote divinity, as it simultaneously makes the subject appear more dominant in the scene and at the same time gives the impression of being seen from below – imagine being a small child in a room full of grown-ups and looking up at their faces lit from above by the lights on the ceiling.
很多有名的宗教片段都用从上射下来的光来表示神，同时把主题显得很在场景是很有统治地位。同时有一种从下向上看的感觉。想像一下，一个小孩在一个有很多大人的房间，向上看他们的脸，而光从天花板上照下来。
More diffuse light is used to communicate a more serene and peacefull atmosphere.
而更多的散射光用来表现一种平静，和平的氛围。
The master of this style (well, arguably the master of light in general) in traditional art was William Bourguerau:
这种风格的大师是William Bourguerau
Le
Crepuscule, by William Adolphe Bouguerau.
黄昏， William Adolphe Bouguerau
The light in this painting is very diffuse, but you can still make out the predominant source of light in the upper left, though fill light in this case comes from all around.
这个光线就是散射型的，但是你还是能感觉到最有影响的还是从左上方过来的，补光就是从四面八方过来的。
This kind of lighting would be best achieved through some kind of GI setup.
这种光照能通过一些GI设定来实现。
Renderers like vray or lux render can do this kind of thing
easily, but it can also be done in blender internal by getting rid of
the fill and back lights, instead environment lighting to provide
illumination for the shadows.
在vray或是lux渲染器中很容易实现，而用内置的blender渲染器就要去掉补光与背光，用环境光来提供对阴影的照明。
A full discussion of how to set this up would be a tutorial of its own, so apart from the settings below I will leave you to experiment with this yourself.
如何设定这种光，就是它们自己的教程了，下边缺少的东西就自己去试吧。
In this render, the subject is lit with only one key light, using environment lighting instead of fill and back lights to provide illumination of the shadowed areas. This results in very smooth lighting.
在上面的渲染中，主题只用主光照明，而用环境光来代替背光与补光。结果看上去非常光滑。
Tips:
Anyway. I hope this tutorial has been interesting and usefull, and I leave you with a few general tips on lighting with spot and area lamps.
不管怎么地，我希望这个教程是有趣，有用的。最后我再给些关于用spot与area灯的绝窍吧。
