Let
S
n
{S^n}
denote the region
0
>
x
i
>
∞
(
i
=
1
,
2
,
…
,
n
)
0 > {x_i} > \infty (i = 1,2, \ldots ,n)
of
n
n
-dimensional Euclidean space
E
n
{E^n}
. Suppose
C
C
is a closed convex body in
E
n
{E^n}
which contains the origin as an interior point. Define
α
C
\alpha C
for each real number
α
⩾
0
\alpha \geqslant 0
to be the magnification of
C
C
by the factor
α
\alpha
and define
C
+
(
m
1
,
…
,
m
n
)
C + ({m_1}, \ldots ,{m_n})
for each point
(
m
1
,
…
,
m
n
)
({m_1}, \ldots ,{m_n})
in
E
n
{E^n}
to be the translation of
C
C
by the vector
(
m
1
,
…
,
m
n
)
({m_1}, \ldots ,{m_n})
. Define the point set
Δ
(
C
,
α
)
\Delta (C,\alpha )
by
Δ
(
C
,
α
)
=
{
α
C
+
(
m
1
+
1
2
,
…
,
m
n
+
1
2
)
:
m
1
,
…
,
m
n
\Delta (C,\alpha ) = \{ \alpha C + ({m_1} + \frac {1} {2}, \ldots ,{m_n} + \frac {1} {2}):{m_1}, \ldots ,{m_n}
nonnegative integers}. The view-obstruction problem for
C
C
is the problem of finding the constant
K
(
C
)
K(C)
defined to be the lower bound of those
α
\alpha
such that any half-line
L
L
given by
x
i
=
a
i
t
(
i
=
1
,
2
,
…
,
n
)
{x_i} = {a_i}t(i = 1,2, \ldots ,n)
, where the
a
i
(
1
⩽
i
⩽
n
)
{a_i}(1 \leqslant i \leqslant n)
are positive real numbers, and the parameter
t
t
runs through
[
0
,
∞
)
[0,\infty )
, intersects
Δ
(
C
,
α
)
\Delta (C,\alpha )
. The paper considers the case where
C
C
is the
n
n
-dimensional cube with side 1, and in this case the constant
K
(
C
)
K(C)
is known for
n
⩽
3
n \leqslant 3
. The paper gives a new proof for the case
n
=
3
n = 3
. Unlike earlier proofs, this one could be extended to study the cases with
n
⩾
4
n \geqslant 4
.