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Comparison of spectra measured by integrating sphere and contact probe

The aim of this exercise is to visualize and compare reflectance spectra acquired by a contact probe (CP) and an integrating sphere (IS) attached to the spectroradiometer ASD FieldSpec 4 Hi-Res. The spectra were collected for homogenous material represented by green colored paper and natural material represented by a green leaf.

  • Prerequisites

    • Installed spreadsheet editor (MS Office Excel, LibreOffice Calc or other) or R
    • Downloaded data (module4/theme3_exercise_spectra_comparision); based on your preferred working environment, use either the fileExercise_M4_T3_data.xlsx (excel spreadsheet) or Exercise_M4_T3_data_CP.txt and Exercise_M4_T3_data_IS.txt (text file)
      The dataset consists of:
      • wavelength (column Wavelength)
      • three spectra measured by contact probe (CP) at three different places of the sample (column paper_CP_XXXXX, leaf_CP_XXXXX)
      • one spectrum measured by integrating sphere (IS) (column IS_green_paper, IS_green_leaf).

  • Tasks

    • Data visualization
    • Compare the reflectance spectra from the integrating sphere and contact probe

1. Data visualization

Prepare graphs displaying all of the reflectance spectra acquired by the contact probe. Do measurements of spectral variability on leaf and paper differ in any way? And if yes, then why? Calculate the median spectra for both materials.

2. Comparision of reflectance spectra

Compare the reflectance spectra acquired by the integrating sphere with the computed median spectra from the contact probe (for both materials). What variations can you find between the spectra?

Exercise solution

Proceed to example solution Comparison of spectra measured by integrating sphere and contact probe - report

Back to theme

Proceed by returning to Principles of laboratory spectroscopy