An introduction to 'upside-down' remote sensing

Over the last decade, a number of applications have been developed which utilize ground-based hemispherical photography. The collection of such imagery can be described as upside-down' remote sensing as, instead of viewing the Earth from a platform in the sky, techniques are being employed to view the sky from the Earth. This paper reviews the current theory and potential applications of 'upside-down' remote sensing across the electromagnetic spectrum. To date, apparatus has been developed to detect various wavelengths between ultraviolet and infrared. Potential applications using these wavelengths are numerous and currently span urban climatology, forest climatology and transportation.