<s>
Occupancy	B-General_Concept
Grid	I-General_Concept
Mapping	I-General_Concept
refers	O
to	O
a	O
family	O
of	O
computer	O
algorithms	O
in	O
probabilistic	O
robotics	O
for	O
mobile	O
robots	O
which	O
address	O
the	O
problem	O
of	O
generating	O
maps	O
from	O
noisy	O
and	O
uncertain	O
sensor	O
measurement	O
data	O
,	O
with	O
the	O
assumption	O
that	O
the	O
robot	O
pose	O
is	O
known	O
.	O
</s>
<s>
Occupancy	B-General_Concept
grids	I-General_Concept
were	O
first	O
proposed	O
by	O
H	O
.	O
Moravec	O
and	O
A	O
.	O
Elfes	O
in	O
1985	O
.	O
</s>
<s>
The	O
basic	O
idea	O
of	O
the	O
occupancy	B-General_Concept
grid	I-General_Concept
is	O
to	O
represent	O
a	O
map	O
of	O
the	O
environment	O
as	O
an	O
evenly	O
spaced	O
field	O
of	O
binary	O
random	O
variables	O
each	O
representing	O
the	O
presence	O
of	O
an	O
obstacle	O
at	O
that	O
location	O
in	O
the	O
environment	O
.	O
</s>
<s>
Occupancy	B-General_Concept
grid	I-General_Concept
algorithms	O
compute	O
approximate	O
posterior	O
estimates	O
for	O
these	O
random	O
variables	O
.	O
</s>
<s>
There	O
are	O
four	O
major	O
components	O
of	O
occupancy	B-General_Concept
grid	I-General_Concept
mapping	I-General_Concept
approach	O
.	O
</s>
<s>
The	O
goal	O
of	O
an	O
occupancy	O
mapping	O
algorithm	O
is	O
to	O
estimate	O
the	O
posterior	O
probability	O
over	O
maps	O
given	O
the	O
data	O
:	O
,	O
where	O
is	O
the	O
map	O
,	O
is	O
the	O
set	O
of	O
measurements	O
from	O
time	O
1	O
to	O
t	O
,	O
and	O
is	O
the	O
set	O
of	O
robot	O
poses	O
from	O
time	O
1	O
to	O
t	O
.	O
The	O
controls	O
and	O
odometry	O
data	O
play	O
no	O
part	O
in	O
the	O
occupancy	B-General_Concept
grid	I-General_Concept
mapping	I-General_Concept
algorithm	O
since	O
the	O
path	O
is	O
assumed	O
known	O
.	O
</s>
<s>
Occupancy	B-General_Concept
grid	I-General_Concept
algorithms	O
represent	O
the	O
map	O
as	O
a	O
fine-grained	O
grid	O
over	O
the	O
continuous	O
space	O
of	O
locations	O
in	O
the	O
environment	O
.	O
</s>
<s>
The	O
most	O
common	O
type	O
of	O
occupancy	B-General_Concept
grid	I-General_Concept
maps	O
are	O
2d	O
maps	O
that	O
describe	O
a	O
slice	O
of	O
the	O
3d	O
world	O
.	O
</s>
