Spectral ratio biospheric Lidar

Beyond 3-D: The new spectrum of lidar applications for earth and ecological sciences

“…(3) lidar allows vertical differentiation of the reflectance signal (x,y,z) (Rall and Knox, 2004;, and (4) Spectral mixing within the measured LRI signal is minimized (e.g., of soil background reflectance and vegetation) due to the relatively small IFOV of the laser pulse (mm for TLS and dm for ALS) combined with the height information it provides (e.g., height above a threshold can assumed to be reflectance from vegetation canopies) (Rall and Knox, 2004;Eitel et al, 2011;Woodhouse et al, 2011).…”

“…However, having only one available wavelength constrains the use of lidar systems to only a few chemical surface properties that happen to distinctively absorb the wavelength employed by the lidar system (Eitel et al, 2011;Nield et al, 2014). One sole wavelength also limits the ability to classify land cover (Fritzmann et al, 2011;Danson et al, 2014;Wang et al, 2013;Hartzell et al, 2014a) and separate ground from vegetation returns (Rall and Knox, 2004;Hancock et al, 2012;Eitel et al, 2014b). Furthermore, a single wavelength does not allow the calculation of spectral vegetation indices that, in addition to enabling corrections of range effects on LRI (e.g., Eitel et al, 2014b), have been shown to reduce noise caused by the viewing and illumination geometry (e.g., .…”

“…In response to these potential limitations of single wavelength LRI, the research community has developed a range of multi-wavelength lidar systems (Irish et al, 1999;Rall and Knox, 2004;Tan and Narayanan, 2004;Woodhouse et al, 2011;Wei et al, 2012;Douglas et al, 2012;Gaulton et al, 2013, Danson et al, 2014, Eitel et al, 2014bNiu et al, 2015;Douglas et al, 2015). A few of these systems are now commercially available (e.g., Optech Titan, Optech Incorporated, Vaughan, Canada; Leica Chiroptera II™, Leica Geosystems, Heerbrugg, Switzerland).…”

Multispectral terrestrial lidar

“…Only the returning laser intensity was analyzed, and range data were not utilized. A horizontal path lidar for chlorophyll estimation in two wavelengths were also presented by Rall and Knox, (2004).…”

“…Vegetation health, productivity and stress level are related to the leaf biophysical parameters, such as, the amount of chlorophyll in plants. Chlorophyll can be monitored by measuring the changes in the so-called vegetation spectral red-edge and estimating the chlorophyll levels with various vegetation indices using values near the red-edge domain (Rall and Knox, 2004). Therefore, there is a strong research interest towards retrieving vegetation spectral indices with multispectral TLS.…”