Animation basics: The optical illusion of motion - TED-Ed

動畫基礎：讓圖畫動起來的視覺錯覺 - TED-Ed

譯者: Kuanju Chou 審譯者: Dong Mao

這是一系列靜止的連續圖形

Take a series of still, sequential images.

Let's look at them one by one.

讓我們一張一張來看

Faster.

再快點

Now, let's remove the gaps,

現在讓我們去除間隔

go faster still.

放得快些

Wait for it ...

等等...

Bam!

...看吧!

Motion!

他動了!

Why is that?

為什麼會這樣?

Intellectually, we know we're just looking at a series of still images,

理智上我們都知道 我們只不過在看

一系列的靜止圖形

but when we see them change fast enough,

但當它們已夠快的速度變化時

they produce the optical illusion of appearing as a single, persistent image

我們看到了從中產生的視錯覺

也就是逐漸變化的外型與位置

來呈現出單一持續的影像

that's gradually changing form and position.

這項效果是所有動畫技術的基礎

This effect is the basis for all motion picture technology,

from our LED screens of today

從今日的 LED 螢幕

to their 20th-century cathode ray forebearers,

回溯到它們在二十世紀的祖先──陰極射線

從影片投影

from cinematic film projection to the novelty toy,

到新奇玩具

甚至有人提出

even, it's been suggested, all the way back to the Stone Age

早在石器時代

人類開始在岩壁作畫時 便已發現這項效果

when humans began painting on cave walls.

This phenomenon of perceiving apparent motion in successive images

這種在連續圖形中

覺察出似動運動的現象

is due to a characteristic of human perception

是由於人類知覺的一項特性

historically referred to as "persistence of vision."

歷史上將它歸為「視覺暫留」

The term is attributed

這名詞的發明歸功於

to the English-Swiss physicist Peter Mark Roget,

瑞士裔的英國物理學家──彼得‧羅傑

who, in the early 19th century,

他在十九世紀早期

used it to describe a particular defect of the eye

將這個辭彙用來形容 一種眼睛特別的缺陷

that resulted in a moving object

也就是在物體移動 到達一定的速度時

appearing to be still when it reached a certain speed.

將移動的物體看成是靜止不動的

Not long after, the term was applied to describe the opposite,

不久之後

這名詞也被用來形容相反的情況

the apparent motion of still images,

也就是靜止圖形中的似動運動

by Belgian physicist Joseph Plateau, inventor of the phenakistoscope.

提出這種說法的人就是 比利時物理學家約瑟夫‧普拉托

費納奇鏡的發明者

他將視覺暫留解釋為

He defined persistence of vision as the result of successive afterimages,

在視網膜中殘留與疊合

which were retained and then combined in the retina,

產生的連續殘像

使我們相信我們所看見的

making us believe that what we were seeing is a single object in motion.

是一個移動中的單一物體

This explanation was widely accepted in the decades to follow

這項解釋在幾十年間

被廣泛接受

and up through the turn of the 20th century,

到了二十世紀時

開始有人質疑

when some began to question what was physiologically going on.

生理上究竟是怎麼運作的

In 1912, German psychologist Max Wertheimer

1912年德國心理學家馬科斯‧韋特墨

outlined the basic primary stages of apparent motion

以簡單的視錯覺

概述了似動運動的基本初始階段

using simple optical illusions.

These experiments led him to conclude

這些實驗引導他總結

該現象的產生是源自於

the phenomenon was due to processes which lie behind the retina.

視網膜後的眾多歷程

In 1915, Hugo Münsterberg,

1915年應用心理學的先驅

a German-American pioneer in applied psychology,

德裔美籍的雨果‧閔斯特伯格

也認為針對連續圖形的

also suggested that the apparent motion of successive images

似動運動

is not due to their being retained in the eye,

並不是由於圖像暫留於眼球裡

but is superadded by the action of the mind.

而是經由心智活動添加

In the century to follow, experiments by physiologists

隨著世紀的演進

生理學家們的實驗

已經能充分證實他們的結論

have pretty much confirmed their conclusions.

As it relates to the illusion of motion pictures,

當我們講到動畫中的錯覺時

persistence of vision has less to do with vision itself

視覺暫留和視覺本身的關連性

than how it's interpreted in the brain.

已遠不及腦內 如何自行解釋來得重要

Research has shown that different aspects of what the eye sees,

研究顯示眼球所見的

各種不同層面

like form, color, depth, and motion,

比如說形狀

顏色

深度

和動作

are transmitted to different areas of the visual cortex

都經由視網膜中不同的路徑

via different pathways from the retina.

傳送到視覺皮質中不同的區域

It's the continuous interaction

視覺皮質中

of various computations in the visual cortex

不同訊息彼此持續的交互作用

that stitch those different aspects together

將各種不同層面的訊息連結在一起

並形成知覺

and culminate in the perception.

Our brains are constantly working,

我們的大腦持續地工作

synchronizing what we see, hear, smell, and touch

同步處理我們所看見的

聽到的

聞到的

into meaningful experience

還有觸摸到的

於當下即時的流動中

將訊息轉化為有意義的體驗

in the moment-to-moment flow of the present.

So, in order to create the illusion of motion in successive images,

所以我們需要計算

接近大腦處理當下 訊息速度的時間間隔

we need to get the timing of our intervals

以創造出

close to the speed at which our brains process the present.

看見連續圖形運動的錯覺

So, how fast is the present happening according to our brains?

那麼當下發生在腦內的 情況究竟有多快呢？

Well, we can get an idea

嗯我們可以試試這個想法

藉由測量圖形需要被改變的速度有多快

by measuring how fast the images need to be changing

for the illusion to work.

才能產生錯覺

Let's see if we can figure it out by repeating our experiment.

我們來看看重複實驗後

我們是不是能弄清楚了

Here's the sequence presented at a rate of one frame per two seconds

這個序列以每兩秒一張

間隔一秒黑屏

的速率呈現

with one second of black in between.

At this rate of change,

照著這樣的速率

with the blank space separating the images,

以空白格將圖片分隔

there's no real motion perceptible.

並無法使人察覺到移動的現象

As we lessen the duration of blank space,

當我們將空白格出現的時間縮短

a slight change in position becomes more apparent,

位置的細微變化開始越發明顯

接著你開始察覺到兩張不同圖片間

and you start to get an inkling of a sense of motion

出現動態效果的跡象

between the disparate frames.

每秒一張

One frame per second.

Two frames per second.

每秒兩張

Four frames per second.

每秒四張

Now we're starting to get a feeling of motion,

現在我們開始感覺到動作了

but it's really not very smooth.

但還不是非常流暢

We're still aware of the fact that we're looking at separate images.

我們仍能察覺到

我們觀看的是各自獨立的圖片

Let's speed up. Eight frames per second.

讓我們加快速度

每秒八張

每秒十二張

12 frames per second.

It looks like we're about there.

看起來我們就快完成了

At 24 frames per second, the motion looks even smoother.

在每秒24張的時候

動作看起來更流暢了

This is standard full speed.

這正是標準的速度

So, the point at which we lose awareness of the intervals

所以我們開始忽略間隔

and begin to see apparent motion

並觀察到似動運動的時間點

似乎發生在每秒8張至每秒12張左右

seems to kick in at around eight to 12 frames per second.

這項結果位於

This is in the neighborhood of what science has determined

科學定義出

我們所能察覺到獨立圖像閾值

to be the general threshold of our awareness

的臨界點附近

of seeing separate images.

總的來說

Generally speaking, we being to lose that awareness

在每張圖片間的間隔約100毫秒

at intervals of around 100 milliseconds per image,

相當於每秒10張的情況下

which is equal to a frame rate of around ten frames per second.

我們開始無法察覺到間隔

As the frame rate increases,

當圖片播放的速度加快時

we lose awareness of the intervals completely

我們會徹底無法察覺到間隔

and are all the more convinced of the reality of the illusion.

並且更加深信

錯覺是真實存在的