Topic Introduction

A spectral signature is the pattern of spectral response for a particular material. In this topic, we will focus on what influences a spectral signature and how we can illustrate one. This is important because in remote sensing we use spectral signatures to distinguish between land-cover types and other surface characteristics.

Topic Readings

Required Readings

There are no required readings.

Optional Readings

• Shellito, B.A. (2014). Chapter 10: How Remote Sensing Works. In E. Bruno (Ed.), Introduction to Geo-Spatial Technologies (2^nd ed., pp. 335-337). New York, NY: W.H. Freeman and Company.

Fundamental Concepts

Lecture Video & Powerpoint

• Spectral Signatures and Vegetation

FODE009_2.2 Spectral Signatures and Vegetation.pdf Download FODE009_2.2 Spectral Signatures and Vegetation.pdf

Self Check (For certificate learning only)

Self-check Quiz 2.2

Quiz Questions:

• What is a specular reflector? Give an example of an Earth surface which acts this way?
• How do the palisade parenchyma cells of a leaf influence its spectral signature?
• What is the relationship between NIR reflectance and health of the vegetation?
• Will a higher leaf moisture content result in a lower or higher reflectance of MIR wavelenths (compared to a lower leaf moisture content)?
• What is the NDVI and how is it applied?

Check Answers:

Instructions: Take the quiz by clicking Self-check Quiz 2.2 and compare your answer with the Model Answer after your attempt.

Activities & Assignments (For certificate learning only)

Class Forum Topic 2.2

Follow detailed requirements in FODE009_Forum Post 2.2.docx Download FODE009_Forum Post 2.2.docx

Assignment/Lab 4: What Can I See? The Electromagnetic Spectrum, Wavelengths and Spectral Signatures.

Assignment/Lab 4 is due this week. Be sure to send in the assignment in Assignment 4 dropbox by 11:59pm on Friday this week.

Topic Summary

Understanding the spectral signature of leaves has led remote sensing analysts to be able to classify different types of forests and predict vegetation health. This is particularly important in forestry when surveying landscapes to evaluate the effects of harvest and determine a sustainable management plan.

Topic Self-review (For self learning)

Please use the reflection questions below as study guide to conduct self-review for the topic.

• What are the spectral signatures for clear water, turbid water, vegetation, soil, ice and clouds? Draw them on a graph from 400 – 2500nm
• At what wavelengths would you expect soil to have higher reflectance than water?
• In what part of the spectrum does healthy vegetation have the highest reflectance?
• Why do leaves appear green except for during senescence/stress?
• Describe some ways in which the NDVI has been improved upon and applied in different situations