Characterizing relationships between population density and nighttime imagery for Denver, Colorado: issues of scale and representation

This paper maps and characterizes the correlation between population density and nighttime imagery over Denver, Colorado. Photographs taken at night from the International Space Station (ISS) have finer spatial and spectral resolution than existing nocturnal observing satellites such as the Defense Meteorological Satellite Program's Operational Linescan System (DMSP OLS). We determined the correlation between the city lights of Denver, Colorado, and several representations of population and population density derived from census data. The DMSP OLS proved to have a stronger correlation than any of the finer resolution ISS photograph bands. This study suggests that exclusive use of nighttime images with finer spatial and spectral resolution will not necessarily improve our ability to use nighttime imagery for modelling traditional representations of population. However, analysis of the spatial patterns of error indicates that finer resolution imagery may be a good proxy of conceptualizations of population density that account for human spatial behaviour. Future research may demonstrate that imagery such as the ISS photographs may prove to be uniquely capable of informing more sophisticated representations of complex phenomena such as ambient population density, land-use intensity and impervious surface.