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ERDAS 1: INTRODUCTION TO ERDAS IMAGINE
GEO 420
Goals:
1. Display raster image using panchromatic, normal & false color.
2. Use zoom tool/buttons to properly display image and inquire
cursor to identify pixel locations and digital numbers.
3. Display image automatically scaled with DN’s stretched from 0-
255, or with natural spectral variation.
• Use histogram to view spectral variability and frequency/proportion of
DN’s within each class.
4. Perform a linear contrast stretch
5. Measure distances and areas within an image.
6. Create spatial and spectral profiles of an image.
1. Displaying an Image• No stretch image• View/Edit Image Metadata
• Lanier.img - Landsat Thematic Mapper (TM) image that has 7 wavebands
of information with 512 rows and columns of raster information.
• You have displayed a False Color Composite which sends Near Infrared
(NIR) Light in TM Band 4 to the Red color gun, Red Light in TM Band 3 to
the Green gun, and Green Light TM Band 2 to the Blue gun.
• Display Options settings - No Stretch – so it looks dark.
• Home > Metadata Icon and choose View/Edit Image Metadata - gives
you all of the info Imagine has on this image (number of layers is 7 for
TM, min and max DN values, the Measurement Units, and the Projection
(if any), etc.
2. Inquire Cursor Utility
Google Earth Capabilities
3. HistogramsType of Image Enhancement: Contrast manipulation – contrast stretching of histogram distn
4. Stretching an image
Swipe
5. Measurements
6. Spectral Profiles• Band 1 = blue (high due to scattering)• Band 2 = green• Band 3 = red• Band 4 = near infrared
• Band 6 = thermal
6. Spatial Profiles
Landsat 7 and TM & ETM+ Characteristics:
Band Spectral Range(µm) Resolution(m)
1 .45 to .51 30
2 .525 to .605 30
3 .63 to .690 30
4 .75 to .90 30
5 1.55 to 1.75 30
7 2.09 to 2.35 30
6 10.40 to 12.5 (thermal) 60
NDVI