ASCII立体图（ASCII stereogram），是ASCII艺术的一种形式，它利用观察图像时，令视线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列字母会呈现远近相间的视觉效果。如果图 1 底部的两个 O 看起来像三个，那么远近效果就会相反。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，垂直线将会变得更深，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
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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。
致谢
图 1、2、3 与 4 分别归属于 David B. Thomas、Jonathan Bowen、Charles Durst 与 Marty Hewes。这四幅立体图出现在公开的 alt.3d USENET 新闻组 中。图 5 是一位维基人现场作出来的。
最初由 ASCII Stereograms 的作者改编而来，并且得到了作者的许可。
外部链接
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