GEOG272-Lab4 (2)

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School

University of Maryland *

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Course

272

Subject

Geography

Date

Feb 20, 2024

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docx

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2

Uploaded by Josephmass

Lab 4 Vegetation Indices Lab Data : GEOG 272 Lab 2 Data.zip . Make sure to download, unzip and save all the files into your own folder. Overview We will be using ENVI to create and analyze typical (widely used) vegetation indices. Please complete the tasks and answer the questions written in RED. Band Ratioing Band ratioing is a process by which brightness values of pixels in one band are divided by the brightness values of their corresponding pixels in another band in order to create a new output image. These ratios may enhance or subdue certain attributes found in the image, depending on the spectral characteristics in each of the two bands chosen. This lab will introduce you to methods of calculating ratio bands and vegetation indices. Open the Landsat image and calculate the Simple Ratio (NIR/Red) using ENVI's Band Math function (Basic tools > Band Math). Enter the following expression: "b4*1.0/b3". ENVI will ask you to select which bands you want to assign to band 4 (NIR) and band 3 (Red). [1] Interpret and discuss the result of NIR/Red ratio. Which type of features is extracted from the band ratioing process? [2] Compare and briefly discuss the values computed for (a) water, (b) vegetation, and (c) urban areas. Scatterplots are valuable image exploration aids. Create a scatterplot under Tools, 2-D Scatterplots. Select the Red band for your x axis, and the NIR band for the y axis. This is an interactive tool, where you can create a ROI on your scatterplot by drawing on the scatterplot and you will see the pixels highlighted in your image window if you right click on the scatterplot window.
[3] Create a two-dimensional scatterplot and see the correlation between the red and NIR bands. Create three ROIs in different colors and make a screenshot of the scatter plot and the main image window. Make a discussion about the land cover type that each ROI represents. Use ENVI's Band Math function introduced above to try generating other vegetation indices.
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