Density + Urban Structure

The urban experience is ultimately about the spaces between buildings.  When we look at the city of Toronto as a whole and analyze site coverage (aka the footprint of the building as a percentage of the total site area) and highlight sites that have high coverage (60% +), we see some obvious results as well as some outlying surprises.  Interestingly, industrial areas along the railway corridors also tend to have high coverage ratios, but presumably low density.  

How can we use this type of analysis to help determine opportunities for infill development?