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