  We have developed a new optical microscopy technique able to track
micron-sized surface clusters as temperature is varied. Potential candidates
for study include phase separated metal-insulator materials, ferroelectrics,
and porous structures. Several key techniques (including autofocus, step
motor/cross correlation alignments, single-pixel thresholding, pair
connectivity correlation length and image convolution) were implemented in
order to obtain a time series of thresholded images. Here, we apply this new
method to probe the archetypal phase separated insulator-metal transition in
VO$_2$. A precise time and temperature series of the insulator-metal transition
was achieved, allowing us to construct for the first time in this material
spatial maps of the transition temperature T$_c$. These maps reveal multiple
interesting features such as fractal electronic patterns on micron scales,
regions of the sample with an extremely large or nearly absent local
hysteresis, a positive correlation between the T$_c$ value and the hysteresis
width $\Delta$T$_c$, and high cycle-to-cycle reproducibility of the transition.
These maps also allow for the identification of individual pixels with unique
transition characteristics. This unprecedented knowledge of the local
properties of each spot along with the behavior of the entire network paves the
way to novel electronics applications enabled by, {\em e.g.}, addressing
specific regions with desired memory and/or switching characteristics, as well
as detailed explorations of open questions in the theory of hysteresis.
