Retrieval of vertical leaf water content using terrestrial full-waveform lidar

Xi Zhu, Andrew K. Skidmore, Roshanak Darvishzadeh, Tiejun Wang

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contribution

Abstract

The vertical distribution of leaf water content (LWC) within plant canopy plays an important role in light penetration and scattering, thus affecting reflectance simulation with radiative transfer models. Although passive remote sensing techniques have been widely applied to estimate LWC, they are unable to retrieve the LWC vertical distribution within canopy. By providing vertical information, terrestrial LiDAR can potentially overcome this limitation. In this paper we investigated the applicability of the terrestrial full-waveform LiDAR to estimate the LWC vertical profile within the canopy of individual plants. A standard radiometric calibration was applied to convert the amplitude and the echo width to a physically well-defined radiometric quantity, namely the backscatter coefficient. However, the backscatter coefficient is strongly affected by the incidence angle between the laser beam and the leaf normal. In order to compensate for incidence angle effects, reference reflectors (Spectralon from Labsphere, Inc.) were used to build a look-up table to calibrated the backscatter coefficient. Our results showed that the backscatter coefficient had a strong correlation (R2 = 0.66) with LWC after correcting for the incidence angle effect. Good agreements were achieved between the predicted vertical profile of LWC and the measured vertical profile of LWC with a mean RMSE (root mean square error) value of 0.001 g/cm2 and a mean MAPE (mean absolute percent error) value of 4.46 %. Our study successfully demonstrated the feasibility of retrieving LWC vertical distribution within plant canopy from a terrestrial full-waveform LiDAR.

Original languageEnglish
Title of host publicationRemote sensing for agriculture, ecosystems, and hydrology XVIII
EditorsChristopher M. U. Neale, Antonino Maltese
Place of PublicationBellingham, Washington
PublisherSPIE
Number of pages8
ISBN (Electronic)9781510604018
ISBN (Print)9781510604001
DOIs
Publication statusPublished - 2016
Externally publishedYes
EventRemote Sensing for Agriculture, Ecosystems, and Hydrology XVIII - Edinburgh, United Kingdom
Duration: 26 Sep 201628 Sep 2016

Publication series

NameProceedings of SPIE
PublisherSPIE
Volume9998
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceRemote Sensing for Agriculture, Ecosystems, and Hydrology XVIII
CountryUnited Kingdom
CityEdinburgh
Period26/09/1628/09/16

Keywords

  • Leaf water content
  • vertical distribution
  • full-waveform
  • terrestrial laser scanner

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