CG中形的層級

老早就想寫類似的，一直比較懶，畢業(yè)論文里提到這個東西，但是這篇所述更加形象直觀而且拓寬了它的面。其實(shí)是很基礎(chǔ)的東西，和點(diǎn)線面這些一樣屬于設(shè)計構(gòu)成的基本層面的東西。但是實(shí)際應(yīng)用中，包括工作中，雖然腦子里都會想著這些，可出來的感覺適合不適合好看不好看又是另一碼事情了。
我們設(shè)計的時候都會說元素，啊，要某個文明的一些感覺，加點(diǎn)gothic的元素，或者steampunk的元素，xx元素，元素。。 拋開這些附著的“皮肉”，構(gòu)成才是所有這些的骨架和精髓。因?yàn)槲覀兘?jīng)常遇到或者看到別人有這種問題：給你一堆很有feel的元素，你設(shè)計出來的東西依舊不那么給力，造型不耐看。

關(guān)于這些造型，或者形，一類是像朱峰說的“道法自然”，即從自然萬物中提取造型，注意是提取而不是挪用，因?yàn)檫@里涉及到你如何簡練優(yōu)化這個形，讓這個形既有他的模仿物得感覺，又帶上設(shè)計物所要傳達(dá)的感覺，譬如科技感。

另外一種即抽象形，比如搜a(bǔ)bstract art，會出來很多圖，但是優(yōu)美和諧與否又是另一回事情。它比較接近我想說的那個，也是我覺得比較難的，就像天賦一樣，某些人天生對這些圖形的感覺就很好。但是這是可以后天訓(xùn)練的。

scott robertson的很多作品都是利用這種抽象構(gòu)成來設(shè)計，包括他的一些場景小稿也是單純從黑白圖形的角度出發(fā)考慮，比如下面這些圖：。 那些場景小稿的啟示就是，對一個事物我們可以從不同的角度去思考，它是和諧優(yōu)美的圖形shape，同樣又是構(gòu)圖composition。我們經(jīng)常就悲哀了，啊，我這個場景感覺不好看啊，起稿的時候就沒有感覺啊。但是你看下面的那些小稿，只是從圖形shape的角度去思考，雖然還只是一些富于變化的抽象形，用了些簡單的顏色區(qū)分，但是已經(jīng)很有feel了。

再來幾張感性認(rèn)識一下：很簡單的一些形狀，但是他的大小變化，分布組合，這些構(gòu)成規(guī)則的運(yùn)用，賦予了簡單的東西很豐富的變化。天天說節(jié)奏韻律，節(jié)奏韻律，這些就是，而且是最本質(zhì)的。你不需要繁復(fù)的花紋和別致的其他什么元素，如果你只用一些簡單的形狀就能做出不俗的shapes，那么恭喜，你的內(nèi)力已經(jīng)上去了，怎么用元素只是外功而已。

下面整合了一些Neil Blevins的文章，小翻譯一下

This lesson is all about Primary, Secondary and Tertiary shapes, what they are and how to use them. This concept is also sometimes referred to as "Big, Medium, Small", as in, if your image has a nice distribution of big (primary), medium (secondary) and small (tertiary) shapes, the resulting image will tend to be more pleasing to the eye.

本課我們來談?wù)勔患壎�級三級形狀，它們是什么，如何利用。這個概念也就是通常我們知道的 大、中、小。假如你的畫面里面，大（一級）、中（二級）、小(三級）形的發(fā)布很nice，那么出來的結(jié)果多少會看著舒服。

First, a definition. Primary shapes are your big shapes. If you squint at an image, the details tend to disappear and you're left with only your big shapes.

Secondary shapes are the smaller shapes that either sit ontop of, or help make up the primary shapes.

Tertiary shapes are again smaller than the secondary shapes.

Here's three 2D diagrams showing primary, secondary and tertiary shapes in a fake composition. Even though this is 2d, the exact same rules apply to 3d.

首先我們來定義一下。 一級形是畫面里最大最顯眼的形，假如你瞇著眼看圖，所有的細(xì)節(jié)消失后那個最大的形狀就是。
二級形，小些的形狀，既可以組合于一級形之上，也可以用于凸顯一級形。
三級形是比二級形更小的形狀。
下面是3個2d圖形，形象直觀的表述了這3個概念，這種原則性的東西對于2d 3d都是適用的。（小插入：在中國對3d的理解太片面了，那么多人天天這個群那個班嚷著要畫畫要設(shè)計，沒見幾個說想成為3d artist。你把設(shè)計理論和造型色彩都掌握好了，必要的“功夫在詩外”的那些功夫都練好了，你管我用畫筆還是刻刀還是鍵盤鼠標(biāo)？我拉一個屌爆了的3d概念藝術(shù)家，相同時間內(nèi)出概念的效率和一個屌爆了的2d concept artist是不相上下的，除了叫speed painting的，還有叫speed sculpture的，試試就知道了 ）
First off, what should the size of these details be? Well, that depends on personal taste. I like having the primary details being huge, almost the size of the image itself. And I like Tertiary details being really small, sometimes the size of a pixel or two. From there you can decide the appropriate size for the Secondary Details. Of course, not all details should be the same size, it's more like a range of sizes, so not all secondary details should be the same size, but should be in a similar range.
首先，那些細(xì)節(jié)應(yīng)該多大？好吧，這個看個人口味。我個人口重，喜歡一級形比較大的，差不多和這張圖差不多大。然后我喜歡把三級形弄的很小，有時候可能只是一兩個像素點(diǎn)。之后呢你可以決定二級形多大合適。當(dāng)然，不是說所有細(xì)節(jié)都要差不多大小，你要給他們一個合理的范圍，合理的區(qū)間。二級形也是同理。
So these could be primary, secondary and tertiary shapes....

But so can these...

And these...

Next comes the distribution of these details. Take a look at this image, it has all 3 levels of detail, but the tertiary shapes are in one uniform block...
下面就來分布分布細(xì)節(jié)（三級形狀）。看看下面這個圖，他是有了3個層級，但是看看那個排列規(guī)則的3級形，我就不想說什么了。。。。

Many images suffer from this problem, huge blocks of small repeating patterns. For example, you get this effect if you place a procedural noise with no variation on a surface.
就像上圖那樣，很多圖像啊，在處理這個細(xì)節(jié)（三級形）的時候都存在這種問題，一大片一大片重復(fù)的相同的小紋理啊我操。就像下圖，用3d軟件的某些程式化紋理的時候就出來這樣的東西，不但假而且毫無變化，無趣。

This does not provide the eye any spot to rest. So in general you want to vary the placement of your tertiary details so that they are more random, and have several areas of detail, and several areas of no detail.
這就不能給眼睛提供一些休息的點(diǎn)，到處東西到處密密匝匝。所以你應(yīng)該給你的三級形的分布多些變化，讓它們更隨機(jī)更自然點(diǎn)。一些地方給點(diǎn)細(xì)節(jié)，一些地方留點(diǎn)白。下面這圖經(jīng)過變化就好多了么。

Notice how this is easier to digest. The eye can look at the detailed lower right corner, then move to the center of the image and rest there for a moment (in the big area of little detail) before looking at more tertiary details elsewhere.
就比如上圖，你的眼睛看到了右下細(xì)節(jié)多的地方，然后視點(diǎn)移往中心的那片留白區(qū)稍事休息，接著又看到其他細(xì)節(jié)多的地方。

This is another reason why natural patterns generally look better than out of the box procedural patterns. Natural patterns tend to have areas of lots of detail, and areas of very little detail, and they're placed in a more random fashion. Of course, through mixing and what not, you can get a more "organic" quality from procedurals, but procedurals right out of the box generally don't give you that kind of variety. See my Complex Shaders Using Procedurals, The Green Tongue lesson for a discussion on how to get more variety from your procedurals.

這就是為什么自然紋理往往看著比軟件的程式化紋理舒服點(diǎn)的原因。自然紋理有一些區(qū)域有很多細(xì)節(jié)，有些區(qū)域有一點(diǎn)一些，并且都是很隨機(jī)的。當(dāng)然，你用max什么的做程式化紋理，只要用些混合手段，出來的效果看著也挺“有機(jī)”的。關(guān)于如何把程式化紋理做的更富于變化，請看我的其他文章。

Here's a photo of a rock in greyscale. Notice the variety in the patterns.
下面是一張巖石的黑白照片，注意上面紋理的變化。

下面這個例子就很好，就算你只有圓柱形，但是如果你手段比較高明，依然可以做出好看的造型。
Here's another example of building up shapes. First, lets start with a cylinder, maybe this will be a pipe for a robot.

Now lets place some secondary shapes, rings around the pipe.
現(xiàn)在放些二級形，環(huán)繞管子的圓環(huán)。

Now that's more interesting, but the regular pattern is kind of boring. Lets vary the position of the secondary rings...
這樣有意思了點(diǎn)，但是圓環(huán)的規(guī)則排布有點(diǎn)boring。那把它們得位置變變。

Better, but all the secondary shapes are the same size, lets vary the sizes a bit...
恩，這樣更好了點(diǎn)，但是所有的二級形都是一樣的大小，我們再來調(diào)整下二級形的大小

Looking better. We now have variety in the sizes of the secondary shapes, and we have areas with lots of secondary shapes, and areas with no secondary shapes. Lets add a few tertiary shapes...
更好了�，F(xiàn)在我們讓二級形在大小上也產(chǎn)生了變化，而且哪些地方有 ，哪些地方?jīng)]有都比較順眼。接著再添加些三級形。

Now we have a well balanced composition.

Here's a few paint overs of some of my images showing the primary, secondary and tertiary shapes...

In this case, the giant tower is the primary shape (a cylinder). That shape is made up of many secondary shapes, pipes and large pieces of concrete, and the entrance. The tertiary shapes are the tiny ships, and tiny lights along the surface of the tower, many of which are just a few pixels large. This helps give the piece a good sense of scale.
上圖，這個巨塔就是一級形（柱形）。這個一級形其實(shí)是很多二級形組合而成的，各種管子啊，大塊得混凝土啊，一些入口一樣的東西啊。三級形在上圖就是一些小飛船，巨塔表面的小燈光，很多這些三級形就是幾個像素的大小。這些呢都很好地體現(xiàn)了畫面中物體的尺寸感覺。

The primary shape is the shape made by the creature against the background. Then there's some larger tentacles, which are secondary shapes. Then there are more tiny tentacles, and grass, etc., which are tertiary shapes. If the image had no tertiary shapes, it would feel like something's missing.

Robots are a great opportunity for practicing "Big, Medium, Small". In this image, the larger shape of the creature is the primary shape. Then that has secondary shapes on it like the front panel or eye. Then those have tiny tertiary shapes on them as well, such as nuts, panel lines, small raised panels, etc. Also note that there aren't tertiary shapes everywhere on the secondary shapes, there are areas of lots of detail, and areas of no detail. Also notice just how small some of the tertiary shapes are compared to the secondary shapes.

機(jī)械物體很適合拿來練習(xí)形的層次組合。上圖的那個玩意兒，本體剪影就是一級形，然后前方的那塊像眼睛的板是二級形。然后它們各自上面又有一些三級細(xì)節(jié)。比如一些螺栓，板上的直線，小點(diǎn)的突出的板等等。同時注意，這些三級細(xì)節(jié)并非搞的到處都是。  然后也請注意，同一些二級形比較，某些三級細(xì)節(jié)顯得很小，這個就是給人關(guān)于他的尺寸比例上的一些暗示。

To summarize, when making your images...