Analyzing Spectral Signatures in Imagine D. Meyer [email protected] E. Wood [email protected].
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Transcript of Analyzing Spectral Signatures in Imagine D. Meyer [email protected] E. Wood [email protected].
Analyzing Spectral Signatures in Imagine
Concept: Spectral Signatures• Locate 5 examples of the following land
cover types and plot them:– conifer forest– mixed forest– water– agriculture (fields with crops)– agriculture (“bare” fields)– dense urban– open urban
RGB: decomposing images
RGB red green blueClass Red Green Blue
Tomato Bright Very dark Very dark
Background Very dark Kinda dark Medium
Green pepper Kinda dark Medium Very dark
Yellow pepper Very bright Kinda bright Very dark
Orange pepper Very bright Kinda dark Very dark
Garlic Very bright Very bright Very bright
Bowl Medium Medium Medium
RGB: spectral signaturesClass Red Green Blue
Tomato Bright Very dark Very dark
Background Very dark Kinda dark Medium
Green pepper Kinda dark Medium Very dark
Yellow pepper Very bright Kinda bright Very dark
Orange pepper Very bright Kinda dark Very dark
Garlic Very bright Very bright Very bright
Bowl Medium Medium Medium
Bright
Very bright
Kinda bright
Medium
Kinda dark
Dark
Very dark
Red Green Blue
Tools• Identify spectral signatures of different land
cover types using tools within Imagine: – Signature editor• Alarm feature• Signature editor statistics
– Areas of interest (AOI’s)• AOI tool
To do:• Using the “inquire” tool, locate 5 examples
of the 7 land cover types (5 different locations each)
• Make a spectral plot of each cover type (5 curves per plot)
• Determine how easy or hard it might be to identify each of the different cover types.
Locate example cover types• Open germtm.img in a viewer, display
bands 5,4,3 as red,green,blue • Using Inquire Cursor, type in file coordinates (make sure project is “file”, not “map”) and locate: x=185, y=480 (conifer forest)
Locate example cover types• Zoom into Selected Area – Note conifers
are darker, redder than mixed forests.
Make a plot of each cover type• From the viewer menu, select AOI > Tools (the AOI tools
icon window should appear). Click on the “create polygon AOI” icon. Draw a polygon around the “conifers” & double click to close.
Make a plot of each cover type (con’t)
• Click on “Classifier” in the ERDAS Imagine bar, and then click on “Signature Editor” (the “Signature Editor” window should appear).
• Click the polygon to select it (should be outlined with a rectangle when selected.
Make a plot of each cover type
• In signature editor, click on the “create polygon” icon
• Right click on the color field of the signature and make it “dark green”
• Label the class “conifer1”
Make a plot of each cover type (con’t)• To make plots in the Signature Editor, use
the “Display Mean Plot Window”– You can make multiple plots by selecting
multiple signatures ,using the multi-plot icon.
Make a plot of each cover type (con’t)• Repeat for each cover type, color
appropriately, • Can you tell where there might be problems discriminating different cover types??
Make a plot of each cover type (con’t)• Uses the image alarm in the signature editor to
locate best guesses of where the class might be in the image.
Make a plot of each cover type (con’t)
• To save the AOI polygons, select “File -> Save -> Save AOI layers as …”, type in the file name “germtm.aoi”, navigate to the results folder and click “okay”.