<s>
Wiggle	B-Algorithm
stereoscopy	I-Algorithm
is	O
an	O
example	O
of	O
stereoscopy	B-Algorithm
in	O
which	O
left	O
and	O
right	O
images	O
of	O
a	O
stereogram	B-Algorithm
are	O
animated	O
.	O
</s>
<s>
This	O
technique	O
is	O
also	O
called	O
wiggle	O
3-D	O
,	O
wobble	O
3-D	O
,	O
or	O
sometimes	O
Piku-Piku	B-Algorithm
(	O
Japanese	O
for	O
"	O
twitching	O
"	O
)	O
.	O
</s>
<s>
The	O
sense	O
of	O
depth	O
from	O
such	O
images	O
is	O
due	O
to	O
parallax	B-Device
and	O
to	O
changes	O
to	O
the	O
occlusion	O
of	O
background	O
objects	O
.	O
</s>
<s>
Wiggle	B-Algorithm
stereoscopy	I-Algorithm
offers	O
the	O
advantages	O
that	O
no	O
glasses	O
or	O
special	O
hardware	O
is	O
required	O
;	O
most	O
people	O
can	O
perceive	O
the	O
effect	O
more	O
quickly	O
than	O
when	O
using	O
cross-eyed	O
and	O
parallel	O
viewing	O
techniques	O
.	O
</s>
<s>
Disadvantages	O
of	O
wiggle	B-Algorithm
stereoscopy	I-Algorithm
are	O
that	O
it	O
does	O
not	O
provide	O
true	O
binocular	B-Algorithm
depth	O
perception	O
;	O
it	O
is	O
not	O
suitable	O
for	O
print	O
media	O
,	O
being	O
limited	O
to	O
displays	O
that	O
can	O
alternate	O
between	O
the	O
two	O
images	O
,	O
and	O
it	O
is	O
difficult	O
to	O
appreciate	O
details	O
in	O
images	O
that	O
are	O
constantly	O
in	O
motion	O
.	O
</s>
<s>
The	O
sense	O
of	O
depth	O
from	O
wiggle	O
3-D	O
images	O
is	O
due	O
to	O
parallax	B-Device
and	O
to	O
changes	O
to	O
the	O
occlusion	O
of	O
background	O
objects	O
.	O
</s>
<s>
Although	O
wiggle	B-Algorithm
stereoscopy	I-Algorithm
permits	O
the	O
perception	O
of	O
stereoscopic	B-Algorithm
images	I-Algorithm
,	O
it	O
is	O
not	O
a	O
"	O
true	O
"	O
three-dimensional	O
stereoscopic	B-Algorithm
display	I-Algorithm
format	O
in	O
the	O
sense	O
that	O
wiggle	B-Algorithm
stereoscopy	I-Algorithm
does	O
not	O
present	O
the	O
eyes	O
with	O
their	O
own	O
separate	O
view	O
each	O
.	O
</s>
<s>
The	O
apparent	O
stereo	O
effect	O
results	O
from	O
syncing	O
the	O
timing	O
of	O
the	O
wiggle	O
and	O
the	O
amount	O
of	O
parallax	B-Device
to	O
the	O
processing	O
done	O
by	O
the	O
visual	O
cortex	O
.	O
</s>
<s>
Three	O
or	O
five	O
images	O
with	O
good	O
parallax	B-Device
may	O
produce	O
a	O
better	O
effect	O
than	O
simple	O
left	O
and	O
right	O
images	O
.	O
</s>
<s>
Wiggling	O
works	O
for	O
the	O
same	O
reason	O
that	O
a	O
transitional	O
pan	O
(	O
or	O
tracking	O
shot	O
)	O
in	O
a	O
film	O
provides	O
good	O
depth	O
information	O
:	O
the	O
visual	O
cortex	O
is	O
able	O
to	O
infer	O
distance	O
information	O
from	O
motion	O
parallax	B-Device
,	O
the	O
relative	O
speed	O
of	O
the	O
perceived	O
motion	O
of	O
different	O
objects	O
on	O
the	O
screen	O
.	O
</s>
<s>
Many	O
small	O
animals	O
bob	O
their	O
heads	O
to	O
create	O
motion	O
parallax	B-Device
(	O
wiggling	O
)	O
so	O
they	O
can	O
better	O
estimate	O
distance	O
prior	O
to	O
jumping	O
.	O
</s>
