Analyzing Spectral Signatures in Imagine D. Meyer E. Wood

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 RGBredgreenblue ClassRedGreenBlue TomatoBrightVery dark BackgroundVery darkKinda darkMedium Green pepperKinda darkMediumVery dark Yellow pepperVery brightKinda brightVery dark Orange pepperVery brightKinda darkVery dark GarlicVery bright BowlMedium

RGB: spectral signatures ClassRedGreenBlue TomatoBrightVery dark BackgroundVery darkKinda darkMedium Green pepperKinda darkMediumVery dark Yellow pepperVery brightKinda brightVery dark Orange pepperVery brightKinda darkVery dark GarlicVery bright BowlMedium Bright Very bright Kinda bright Medium Kinda dark Dark Very dark RedGreenBlue

Vegetation color (“spectra”)

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”.

Make a plot of each cover type (con’t) To manipulate the layers in the viewer (the 3-color image itself, the AOI polygons, or the “Alarm mask” generated above), right-click on the image..