  Due to the corresponding fact concerning Hilbert spaces, it is natural to ask
if the linearity and the orthogonality structure of a Hilbert $C^*$-module
determine its $C^*$-algebra-valued inner product. We verify this in the case
when the $C^*$-algebra is commutative (or equivalently, we consider a Hilbert
bundle over a locally compact Hausdorff space). More precisely, a
$\mathbb{C}$-linear map $\theta$ (not assumed to be bounded) between two
Hilbert $C^*$-modules is said to be "orthogonality preserving" if
$\left<\theta(x),\theta(y)\right> =0$ whenever $\left<x,y\right> =0$. We prove
that if $\theta$ is an orthogonality preserving map from a full Hilbert
$C_0(\Omega)$-module $E$ into another Hilbert $C_0(\Omega)$-module $F$ that
satisfies a weaker notion of $C_0(\Omega)$-linearity (known as "localness"),
then $\theta$ is bounded and there exists $\phi\in C_b(\Omega)_+$ such that $$
\left<\theta(x),\theta(y)\right>\ =\ \phi\cdot\left<x,y\right>, \quad \forall
x,y \in E. $$ On the other hand, if $F$ is a full Hilbert $C^*$-module over
another commutative $C^*$-algebra $C_0(\Delta)$, we show that a
"bi-orthogonality preserving" bijective map $\theta$ with some "local-type
property" will be bounded and satisfy $$ \left<\theta(x),\theta(y)\right>\ =\
\phi\cdot\left<x,y\right>\circ\sigma, \quad \forall x,y \in E $$ where $\phi\in
C_b(\Omega)_+$ and $\sigma: \Delta \rightarrow \Omega$ is a homeomorphism.
