ASCII立体图

ASCII立体图（ASCII stereogram），是ASCII艺术的一种形式，它利用觀察图像時，令視線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 看起来像三个，确保中间那个 O 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：7列字母會呈現遠近相間的視覺效果。如果图 1 底部的两个 O 看起来像三个，那么遠近效果就会相反。另外也可以通过视线交叉观察到相反的三维效果。
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
                          O          O
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，垂直線将会變得更深，因而增加立体效果，水平或者竖直方向稍微移动也会产生有趣的效果。
O          O
.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .
   .    .    .    .    .    .    .    .    .    .    .    .    .
   .     .     .     .     .     .     .     .     .     .     .
     .      .      .      .      .      .      .      .      .
 .       .       .       .       .       .       .       .       .
      .        .        .        .        .        .        .
   .         .         .         .         .         .         .
.          .          .          .          .          .          .
|          |          |          |          |          |          |
|          |          |          |          |          |          |
|          |          |          |          |          |          |
|          |          |          |          |          |          |
|          |          |          |          |          |          |
|          |          |          |          |          |          |
   .         .         .         .         .         .         .
      .        .        .        .        .        .        .
 .       .       .       .       .       .       .       .       .
     .      .      .      .      .      .      .      .      .
   .     .     .     .     .     .     .     .     .     .     .
   .    .    .    .    .    .    .    .    .    .    .    .    .
 .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .
.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
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”。
O              O
OIWEQPOISDFBKJFOIWEQPOISDFBKJFOIWEQPOISDFBKJFOIWEQPOISDFBKJF
EDGHOUIEROUIYWEVDGHOXUIEROIYWEVDGHEOXUIEOIYWEVDGHEOXUIEOIYWE
KJBSVDBOIWERTBAKJBSVEDBOIWRTBAKJBSOVEDBOWRTBAKJBSOVEDBOWRTBA
SFDHNWECTBYUVRGSFDHNYWECTBUVRGSFDHCNYWECBUVRGSFDHCNYWECBUVRG
HNOWFHLSFDGWVRGHNOWFGHLSFDWVRGHNOWSFGHLSDWVRGHNLOWSFGLSDWVRG
YPOWVXTNWFECHRGYPOWVEXTNWFCHRGYPOWNVEXTNFCHRGYPWOWNVETNFCHRG
SVYUWXRGTWVETUISVYUWVXRGTWVETUISVYUWVXRGWVETUISVYUWVXRGWVETU
WVERBYOIAWEYUIVWVERBEYOIAWEYUIVWVERBEYOIWEYUIVWLVERBEOIWEYUI
EUIOETOUINWEBYOEUIOEWTOUINWEBYOEUIOEWTOUNWEBYOETUIOEWOUNWEBY
WFVEWVETN9PUW4TWFVEWPVETN9UW4TWFVETWPVET9UW4TWFBVETWPET9UW4T
NOUWQERFECHIBYWNOUWQXERFECIBYWNOUWFQXERFCIBYWNOFUWFQXRFCIBYW
VEHWETUQECRFVE[VEHWERTUQECFVE[VEHWQERTUQCFVE[VEOHWQERUQCFVE[
UIWTUIRTWUYWQCRUIWTUYIRTWUWQCRUIWTXUYIRTUWQCRUIBWTXUYRTUWQCR
IYPOWOXNPWTHIECIYPOWTOXNPWHIECIYPONWTOXNWHIECIYLPONWTXNWHIEC
R9UHWVETPUNRQYBR9UHWVETPUNRQYBR9UHWVETPUNRQYBR9UHWVETPUNRQYB
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。
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。
According    to    the  According    to    the
police      inspector,  police      inspector,
Edward  John Billings,  Edward John  Billings,
there  are   too  many  there  are   too  many
individuals  too close  individuals  too close
to  the  case to  make  to  the  case to  make
an  arrest.   I  asked  an  arrest.   I  asked
Mary  Smith to comment  Mary Smith  to comment
on  the case,  but she  on  the case,  but she
declined  to  comment,  declined  to  comment,
because  she  is  soon  because  she is   soon
to   be   married   to  to   be   married   to
Howard  D. Fredericks,  Howard  D. Fredericks,
the   victim's  uncle.  the   victim's  uncle.
Charles   Wilson,  the  Charles   Wilson,  the
victim's      brother,  victim's      brother,
stated that  the chaos  stated that  the chaos
was   responsible  for  was  responsible   for
at least  five suicide  at least  five suicide
attempts   last   week  attempts   last   week
alone.                  alone.
另外也可以实现 ASCII 立体图动画。