<s>
In	O
computer	O
graphics	O
,	O
a	O
procedural	B-Data_Structure
surface	I-Data_Structure
is	O
a	O
representation	O
of	O
a	O
surface	O
as	O
a	O
mathematical	O
implicit	O
equation	O
,	O
rather	O
than	O
an	O
explicit	O
representation	O
.	O
</s>
<s>
A	O
procedural	B-Data_Structure
surface	I-Data_Structure
is	O
one	O
which	O
is	O
defined	O
as	O
a	O
procedure	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
CAD/Computer	O
-aided	O
manufacturing	O
milling	O
applications	O
,	O
an	O
offset	O
surface	O
is	O
a	O
procedural	O
representation	O
because	O
it	O
is	O
defined	O
as	O
the	O
surface	O
which	O
is	O
a	O
fixed	O
distance	O
from	O
another	O
surface	O
.	O
</s>
<s>
Another	O
example	O
of	O
a	O
procedural	B-Data_Structure
surface	I-Data_Structure
is	O
a	O
Blob	O
as	O
illustrated	O
in	O
movies	O
like	O
The	O
Abyss	O
in	O
the	O
scene	O
where	O
the	O
creature	O
made	O
up	O
of	O
water	O
reaches	O
out	O
and	O
touches	O
the	O
character	O
.	O
</s>
<s>
The	O
surface	O
is	O
defined	O
as	O
a	O
surface	O
which	O
exists	O
when	O
two	O
or	O
more	O
control	B-Algorithm
points	I-Algorithm
are	O
oriented	O
in	O
such	O
a	O
way	O
as	O
to	O
make	O
the	O
contribution	O
potential	O
exceed	O
a	O
certain	O
threshold	O
.	O
</s>
<s>
Such	O
procedural	B-Data_Structure
surfaces	I-Data_Structure
require	O
far	O
more	O
processing	O
to	O
calculate	O
,	O
and	O
for	O
this	O
reason	O
are	O
often	O
used	O
in	O
pre-rendered	O
rather	O
than	O
real-time	O
applications	O
.	O
</s>
