ASCII立体图

维基百科，自由的百科全书

ASCII立体图（en:ASCII stereogram）是ASCII艺术的一种形式，它用一幅图像或者一对相邻的图像使眼睛产生适当的交叉从而生成三维图像的错视。

以图 1 为例，为了得到三维效果，观察者需要使眼睛偏离聚焦状态，这样同一行中的两个相邻字符就会贴近到一起。为了帮助聚焦，努力使两个顶上的两个大写字母 O 看起来像 3，确保中心点的图像稳定并且位于焦点之上。一旦做到了这一点，往下看下面的图像，这时三维效果就很明显了。如果图 1 底部的两个 O 看起来像 3，那么效果就会倒退回来。另外也可以通过视线交叉观察到相反的三维效果，但是这做起来更加困难。

图 1: 远近距离

                             O    O
n   n   n   n   n   n   n   n   n   n   n   n   n   n   n   n   n
f    f    f    f    f    f    f    f    f    f    f    f    f    f
e   e   e   e   e   e   e   e   e   e   e   e   e   e   e   e   e
a    a    a    a    a    a    a    a    a    a    a    a    a    a
a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a
r    r    r    r    r    r    r    r    r    r    r    r    r    r
r   r   r   r   r   r   r   r   r   r   r   r   r   r   r   r   r

图 2 的效果更加有戏剧性。一旦看到了三维效果，观察者渐渐远离屏幕将会逐渐增加立体效果，水平或者竖直方向稍微移动也会产生有趣的效果。

图 3 根据与单图像随机点立体图（Single Image Random Dot Stereogram，简称 SIRDS）同样的思想显示了一个 单图像随机文本立体图（Single Image Random Text Stereogram，简称 SIRTS）。当立体图像变得清楚的时候就可以看到浮雕中的“Hi”。

有人在电子邮件末尾或者新闻文章后面用立体图作为“签名”，图 4 就是一个这样的例子。

图 2: 地板、墙壁与天花板

                           O          O
.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .
   .    .    .    .    .    .    .    .    .    .    .    .    .
   .     .     .     .     .     .     .     .     .     .     .
     .      .      .      .      .      .      .      .      .
 .       .       .       .       .       .       .       .       .
      .        .        .        .        .        .        .
   .         .         .         .         .         .         .
.          .          .          .          .          .          .
|          |          |          |          |          |          |
|          |          |          |          |          |          |
|          |          |          |          |          |          |
|          |          |          |          |          |          |
|          |          |          |          |          |          |
|          |          |          |          |          |          |
   .         .         .         .         .         .         .
      .        .        .        .        .        .        .
 .       .       .       .       .       .       .       .       .
     .      .      .      .      .      .      .      .      .
   .     .     .     .     .     .     .     .     .     .     .
   .    .    .    .    .    .    .    .    .    .    .    .    .
 .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .
.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .

图 3: A single image random text stereogram.

                      O              O
OIWEQPOISDFBKJFOIWEQPOISDFBKJFOIWEQPOISDFBKJFOIWEQPOISDFBKJF
EDGHOUIEROUIYWEVDGHOXUIEROIYWEVDGHEOXUIEOIYWEVDGHEOXUIEOIYWE
KJBSVDBOIWERTBAKJBSVEDBOIWRTBAKJBSOVEDBOWRTBAKJBSOVEDBOWRTBA
SFDHNWECTBYUVRGSFDHNYWECTBUVRGSFDHCNYWECBUVRGSFDHCNYWECBUVRG
HNOWFHLSFDGWVRGHNOWFGHLSFDWVRGHNOWSFGHLSDWVRGHNLOWSFGLSDWVRG
YPOWVXTNWFECHRGYPOWVEXTNWFCHRGYPOWNVEXTNFCHRGYPWOWNVETNFCHRG
SVYUWXRGTWVETUISVYUWVXRGTWVETUISVYUWVXRGWVETUISVYUWVXRGWVETU
WVERBYOIAWEYUIVWVERBEYOIAWEYUIVWVERBEYOIWEYUIVWLVERBEOIWEYUI
EUIOETOUINWEBYOEUIOEWTOUINWEBYOEUIOEWTOUNWEBYOETUIOEWOUNWEBY
WFVEWVETN9PUW4TWFVEWPVETN9UW4TWFVETWPVET9UW4TWFBVETWPET9UW4T
NOUWQERFECHIBYWNOUWQXERFECIBYWNOUWFQXERFCIBYWNOFUWFQXRFCIBYW
VEHWETUQECRFVE[VEHWERTUQECFVE[VEHWQERTUQCFVE[VEOHWQERUQCFVE[
UIWTUIRTWUYWQCRUIWTUYIRTWUWQCRUIWTXUYIRTUWQCRUIBWTXUYRTUWQCR
IYPOWOXNPWTHIECIYPOWTOXNPWHIECIYPONWTOXNWHIECIYLPONWTXNWHIEC
R9UHWVETPUNRQYBR9UHWVETPUNRQYBR9UHWVETPUNRQYBR9UHWVETPUNRQYB

图 4: 一个立体图签名

 IIIIIIIIIIIIIII   IIIIIIIIIIIIIII  
 H ( )  \|/    H   H   ( )   \|/ H  
 H(   ) -O-    H   H  (   )  -O- H  
 H     )/|\    H   H (     ) /|\ H  
 H======^======H   H======^======H  
 H- |----@-----H   H----| ---@---H  
 H /|\ @\|/ @  H   H   /|\@ \|/@ H 
 H    \|/  \|/ H   H     \|/  \|/H  
 III^IIIIIII^III   III^IIIIIII^III  
Wide eyed stereo  Wide  eyed  stereo

立体效果可以用于突出文本中的单个字词作为“秘密消息”，当段落调整的时候这个效果可能就被隐藏起来。

图 5: 单词强调

According to  the police inspector,   According to  the police inspector,
Edward   John Billings,  there  are   Edward  John  Billings,  there  are
too  many individuals too  close to   too  many individuals too  close to
the case to make an arrest. I asked   the case to make an arrest. I asked
Mary  Smith to comment on the case,   Mary Smith  to comment on the case,
but she declined to comment, on the   but she declined to comment, on the
grounds that she  is engaged to  be   grounds that she is  engaged to  be
married to  Howard Fredericks,  the   married to  Howard Fredericks,  the
victim's  uncle.   Charles  Wilson,   victim's  uncle.   Charles  Wilson,
the victim's brother,  stated  that   the victim's brother,  stated  that
the chaos  was  responsible for  at   the chaos  was responsible  for  at
least  five suicide  attempts  last   least  five suicide  attempts  last
week alone.                           week alone.

另外也可以实现 ASCII 立体图动画。