A common parameter used to characterize the geometry of urban canyons is the sky-view factor ( s ). Here, two simple alternatives are presented that can be used both objectively and rapidly to estimate s . The first method uses a Nikon CoolPix 950 digital camera fitted with a Nikon FC-E8 fisheye lens. The second method involves a LI-COR LAI-2000 Plant Canopy Analyzer to measure automatically diffuse non-interceptance (DIFN) light using a fisheye optical sensor. Through a series of intercomparisons for urban canyons of known geometry, the digital camera is shown to provide accurate estimates of s . The LAI-2000 also performs well, although it tends to over-estimate s (for the conditions considered here, the mean absolute error is 0.04), and has a more restricted set of sky conditions under which it performs well (ideally, uniform overcast skies). For both methods, data collection and post-processing is rapid, and storage of data is straightforward. Thus, mobile data collection is possible which allows detailed information on the spatial variability of s in urban areas to be determined. An example of such an application for a small US city, Bloomington, IN, is presented.
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