1 Introduction to Remote Sensing Objective: The objective of this tutorial is to show you 1) How to create NDVI images to map the amount of green vegetation in an area 2) How to conduct a supervised classification to map land cover Note: This tutorial is written for PCs running Windows 7, so some parts of the tutorial might not work for you if you are using a Mac or running a different version of Windows. You will be using MultiSpec for this tutorial. You can access MultiSpec by double-clicking the program shortcut on the desktop of any MOSS computer. If you are using your own computer, you can download MultiSpec for free from the Internet at: https://engineering.purdue.edu/~biehl/MultiSpec. The Normalized Difference Vegetation Index (NDVI) STEP 1: Basics The Normalized Difference Vegetation Index (NDVI) can be used to map the amount of green vegetation in an area. The ability of NDVI to measure the amount of green vegetation is based on the principle that green vegetation absorbs radiation in the visible region of the electromagnetic spectrum to use it for photosynthesis – a process during which light energy is converted into chemical energy. In contrast to visible light, near infrared (NIR) light is not used for photosynthesis and is strongly reflected by the plant. The NDVI is typically calculated as follows: NDVI = (NIR – R)/(NIR + R) where R is the reflectance in the red region of the electromagnetic spectrum and NIR is the reflectance in the near infrared spectral region. Use Fig. 1 below to calculate NDVI of the soil, 1 leaf layer, and 2 leaf layers. Write the results of your calculations in the space provided below. For this exercise, let’s assume that red (R) is at 680 nanometers (nm) and NIR at 800 nm. You should be able to get all the reflectance
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1
Introduction to Remote Sensing
Objective: The objective of this tutorial is to show you
1) How to create NDVI images to map the amount of green vegetation in an area
2) How to conduct a supervised classification to map land cover
Note: This tutorial is written for PCs running Windows 7, so some parts of the tutorial might not work for
you if you are using a Mac or running a different version of Windows. You will be using MultiSpec for
this tutorial. You can access MultiSpec by double-clicking the program shortcut on the desktop of any
MOSS computer. If you are using your own computer, you can download MultiSpec for free from the
Internet at: https://engineering.purdue.edu/~biehl/MultiSpec.
The Normalized Difference Vegetation Index (NDVI)
STEP 1: Basics
The Normalized Difference Vegetation Index (NDVI) can be used to map the amount of green vegetation
in an area. The ability of NDVI to measure the amount of green vegetation is based on the principle that
green vegetation absorbs radiation in the visible region of the electromagnetic spectrum to use it for
photosynthesis – a process during which light energy is converted into chemical energy. In contrast to
visible light, near infrared (NIR) light is not used for photosynthesis and is strongly reflected by the plant.
The NDVI is typically calculated as follows:
NDVI = (NIR – R)/(NIR + R)
where R is the reflectance in the red region of the electromagnetic spectrum and NIR is the reflectance in
the near infrared spectral region. Use Fig. 1 below to calculate NDVI of the soil, 1 leaf layer, and 2 leaf
layers. Write the results of your calculations in the space provided below. For this exercise, let’s assume
that red (R) is at 680 nanometers (nm) and NIR at 800 nm. You should be able to get all the reflectance
2
values you need for your calculations from Fig. 1. Please feel free to use the calculator on your computer
for calculating NDVI.
Figure 1. Spectral response curve of soil, 1 leaf layer, and 2 leaf layers.