Preprocessing Ground-Based Visible/Near Infrared Imaging Spectroscopy Data Affected by Smile Effects

Henning Buddenbaum, Michael S. Watt, Rebecca C. Scholten, Joachim Hill

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

A data set of very high-resolution visible/near infrared hyperspectral images of young Pinus contorta trees was recorded to study the effects of herbicides on this invasive species. The camera was fixed on a frame while the potted trees were moved underneath on a conveyor belt. To account for changing illumination conditions, a white reference bar was included at the edge of each image line. Conventional preprocessing of the images, i.e., dividing measured values by values from the white reference bar in the same image line, failed and resulted in bad quality spectra with oscillation patterns that are most likely due to wavelength shifts across the sensor's field of view (smile effect). An additional hyperspectral data set of a Spectralon white reference panel could be used to characterize and correct the oscillations introduced by the division, resulting in a high quality spectra that document the effects of herbicides on the reflectance characteristics of coniferous trees. While the spectra of untreated trees remained constant over time, there were clear temporal changes in the spectra of trees treated with both herbicides. One herbicide worked within days, the other one within weeks. Ground-based imaging spectroscopy with meaningful preprocessing proved to be an appropriate tool for monitoring the effects of herbicides on potted plants.

Original languageEnglish
Article number1543
Pages (from-to)1-11
Number of pages11
JournalSensors (Basel, Switzerland)
Volume19
Issue number7
DOIs
Publication statusPublished - 30 Mar 2019

Funding

Funding: This research was partly funded by the German Aerospace Center (DLR) and the German Federal Ministry of Economic Affairs and Energy in the framework of the EnMAP project, grant number 50 EE 1530. R.S. was supported by the DAAD-PROMOS program. The New Zealand funding for the project was obtained by the Winning Against Wildings programme (Contract Number C09X1611) funded by the New Zealand Ministry for Business, Innovation, and Employment. This funding was supplemented by co-funding from the Forest Growers Levy Trust and Scion’s Strategic Science Investment Fund.

FundersFunder number
DAAD-PROMOSC09X1611
German Federal Ministry of Economic Affairs and Energy50 EE 1530
New Zealand Ministry for Business, Innovation, and Employment
Deutsches Zentrum für Luft- und Raumfahrt

    Keywords

    • Specim FX10
    • field imaging spectroscopy
    • forestry
    • herbicide
    • invasive species
    • preprocessing

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