<s>
A	O
metric	B-Data_Structure
tree	I-Data_Structure
is	O
any	O
tree	B-Application
data	I-Application
structure	I-Application
specialized	O
to	O
index	O
data	O
in	O
metric	O
spaces	O
.	O
</s>
<s>
Metric	B-Data_Structure
trees	I-Data_Structure
exploit	O
properties	O
of	O
metric	O
spaces	O
such	O
as	O
the	O
triangle	O
inequality	O
to	O
make	O
accesses	O
to	O
the	O
data	O
more	O
efficient	O
.	O
</s>
<s>
Examples	O
include	O
the	O
M-tree	B-Data_Structure
,	O
vp-trees	B-Data_Structure
,	O
cover	B-Data_Structure
trees	I-Data_Structure
,	O
MVP	B-Data_Structure
trees	I-Data_Structure
,	O
and	O
BK-trees	B-Data_Structure
.	O
</s>
<s>
Most	O
algorithms	O
and	O
data	B-General_Concept
structures	I-General_Concept
for	O
searching	O
a	O
dataset	O
are	O
based	O
on	O
the	O
classical	O
binary	O
search	O
algorithm	O
,	O
and	O
generalizations	O
such	O
as	O
the	O
k-d	B-Data_Structure
tree	I-Data_Structure
or	O
range	B-Data_Structure
tree	I-Data_Structure
work	O
by	O
interleaving	O
the	O
binary	O
search	O
algorithm	O
over	O
the	O
separate	O
coordinates	O
and	O
treating	O
each	O
spatial	O
coordinate	O
as	O
an	O
independent	O
search	O
constraint	O
.	O
</s>
<s>
These	O
data	B-General_Concept
structures	I-General_Concept
are	O
well-suited	O
for	O
range	B-General_Concept
query	I-General_Concept
problems	O
asking	O
for	O
every	O
point	O
that	O
satisfies	O
and	O
.	O
</s>
<s>
If	O
there	O
is	O
no	O
structure	O
to	O
the	O
similarity	O
measure	O
then	O
a	O
brute	B-Algorithm
force	I-Algorithm
search	I-Algorithm
requiring	O
the	O
comparison	O
of	O
the	O
query	O
image	O
to	O
every	O
image	O
in	O
the	O
dataset	O
is	O
the	O
best	O
that	O
can	O
be	O
done	O
.	O
</s>
<s>
The	O
first	O
article	O
on	O
metric	B-Data_Structure
trees	I-Data_Structure
,	O
as	O
well	O
as	O
the	O
first	O
use	O
of	O
the	O
term	O
"	O
metric	B-Data_Structure
tree	I-Data_Structure
"	O
,	O
published	O
in	O
the	O
open	O
literature	O
was	O
by	O
Jeffrey	O
Uhlmann	O
in	O
1991	O
.	O
</s>
<s>
Other	O
researchers	O
were	O
working	O
independently	O
on	O
similar	O
data	B-General_Concept
structures	I-General_Concept
.	O
</s>
<s>
In	O
particular	O
,	O
Peter	O
Yianilos	O
claimed	O
to	O
have	O
independently	O
discovered	O
the	O
same	O
method	O
,	O
which	O
he	O
called	O
a	O
vantage	B-Data_Structure
point	I-Data_Structure
tree	I-Data_Structure
(	O
VP-tree	B-Data_Structure
)	O
.	O
</s>
<s>
The	O
research	O
on	O
metric	B-Data_Structure
tree	I-Data_Structure
data	B-General_Concept
structures	I-General_Concept
blossomed	O
in	O
the	O
late	O
1990s	O
and	O
included	O
an	O
examination	O
by	O
Google	O
co-founder	O
Sergey	O
Brin	O
of	O
their	O
use	O
for	O
very	O
large	O
databases	O
.	O
</s>
<s>
The	O
first	O
textbook	O
on	O
metric	O
data	B-General_Concept
structures	I-General_Concept
was	O
published	O
in	O
2006	O
.	O
</s>
<s>
Matlab	O
:	O
Metric	B-Data_Structure
trees	I-Data_Structure
are	O
implemented	O
in	O
the	O
metricTree	O
class	O
that	O
is	O
part	O
of	O
the	O
United	O
States	O
Naval	O
Research	O
Laboratory	O
's	O
free	O
Tracker	O
Component	O
Library	O
.	O
</s>
