  The grid obstacle representation, or alternately, $\ell_1$-obstacle
representation of a graph $G=(V,E)$ is an injective function $f:V \rightarrow
\mathbb{Z}^2$ and a set of point obstacles $\mathcal{O}$ on the grid points of
$\mathbb{Z}^2$ (where no vertex of $V$ has been mapped) such that $uv$ is an
edge in $G$ if and only if there exists a Manhattan path between $f(u)$ and
$f(v)$ in $\mathbb{Z}^2$ avoiding the obstacles of $\mathcal{O}$ and points in
$f(V)$. This work shows that planar graphs admit such a representation while
there exist some non-planar graphs that do not admit such a representation.
Moreover, we show that every graph admits a grid obstacle representation in
$\mathbb{Z}^3$. We also show NP-hardness result for the point set embeddability
of an $\ell_1$-obstacle representation.
