LANDSAT Image Processing and GIS...

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Band 3 Band 2 Band 1 Band 4 Band 3 Band 2 Band 1 Band 8 True Color (RGB) Image False Color (143) Image Panchromatic (PAN) Image LANDSAT 7 is a satellite which records 8 bands of reflected electromagnetic energy. These bands range from the visible spectrum (Red, Green, and Blue Bands) to short and long-wave Infra-Red heat bands. The data from each band is recorded in a matrix of 8-bit pixels. Each pixel is given a value from 0 to 255 indicating the amount of energy reflected by that wavelength. Adobe Photoshop can be used to create 24-bit RGB color images by combining 3 of the 8-bit LANDSAT bands. These bands appear grey becaue all three color channels (RGB channels) have the same value of 0 to 255 for each pixel. In order to create a color image the LANDSAT bands are combined in a certain pattern depending on which image is to be made. The image above is a True Color (RGB) image. These images use the energy in the visible light spectrum in their respec- tive channel. Bands 1,2 and 3 are used. This image is easy to interpret. The water is blue, the plants are green and the urban areas are the whitish regions. The image below is a Panchromatic (PAN) image. This image is a higher quality image because it does not capture any specific energy band it captures the information in greyscale. The reason that it looks different from band 8 is because a band stretch was performed in Photoshop to enhance the image. Photoshop Channels Photoshop Channels Photoshop Channels The Color Infra-Red (CIR) image to the left is a little confusing. The plant areas show up as red. This is because of the way that plants reflect light energy absorbing some energy and reflecting the rest. The light-blue areas are urban areas. The image below, is a False Color (143) image. This image uses the blue band in its correct place as well as the red band in its channel but substitutes the infra- red band for the green channel. Plant regions are green while the urban areas show up as purple. In order to properly display one of the LANDSAT images, a World file must be created. A World file is a simple six-line file that specifies the size of the pixels (first four lines) as well as the UTM coordi- nates of the center of the image’s upper-left corner (the remaining two lines). With a World file, these images can be brought into a program such as ArcMap where geographic data, such as roads and elevation data, can be draped over the picture. Data Acquisition Data Processing World Files 15.0000000000000 0.00000000000000 0.00000000000000 -15.000000000000 304792.500000000 4891807.50000000 30.0000000000000 0.00000000000000 0.00000000000000 -30.000000000000 304800.000000000 4891800.00000000 World File for 30 meter pixel RGB, CIR & 143 images World File for 15 meter pixel PAN image LANDSAT Image Processing and GIS Applications By Jake McDonald When an image is projected in ArcMap, other geographic layers can be overlaid on the image. The first image to the right is the RGB image taken into ArcScene and uses elevation data from the USGS to create a 3-D image. The image above this is the 143 image with roads draped on top. Color Infra-Red (CIR) Image GIS Applications 143 with Road Drape 3-D RGB image 8-bit Greyscale Image Red Red Blue Blue Green Green Infra-Red Grey

Transcript of LANDSAT Image Processing and GIS...

Band 3

Band 2

Band 1

Band 4

Band 3

Band 2

Band 1

Band 8

True Color (RGB) ImageFalse Color (143) Image

Panchromatic (PAN) Image

LANDSAT 7 is a satellite which records 8 bands of reflected electromagnetic energy. These bands range from the visible spectrum (Red, Green, and Blue Bands) to short and long-wave Infra-Red heat bands. The data from each band is recorded in a matrix of 8-bit pixels. Each pixel is given a value from 0 to 255 indicating the amount of energy reflected by that wavelength.

Adobe Photoshop can be used to create 24-bit RGB color images by combining 3 of the 8-bit LANDSAT bands. These bands appear grey becaue all three color channels (RGB channels) have the same value of 0 to 255 for each pixel. In order to create a color image the LANDSAT bands are combined in a certain pattern depending on which image is to be made.

The image above is a True Color (RGB) image. These images use the energy in the visible light spectrum in their respec-tive channel. Bands 1,2 and 3 are used. This image is easy to interpret. The water is blue, the plants are green and the urban areas are the whitish regions. The image below is a Panchromatic (PAN) image. This image is a higher quality image because it does not capture any specific energy band it captures the information in greyscale. The reason that it looks different from band 8 is because a band stretch was performed in Photoshop to enhance the image.

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The Color Infra-Red (CIR) image to the left is a little confusing. The plant areas show up as red. This is because of the way that plants reflect light energy absorbing some energy and reflecting the rest. The light-blue areas are urban areas.The image below, is a False Color (143) image. This image uses the blue band in its correct place as well as the red band in its channel but substitutes the infra-red band for the green channel. Plant regions are green while the urban areas show up as purple.

In order to properly display one of the LANDSAT images, a World file must be created. A World file is a simple six-line file that specifies the size of the pixels (first four lines) as well as the UTM coordi-nates of the center of the image’s upper-left corner (the remaining two lines). With a World file, these images can be brought into a program such as ArcMap where geographic data, such as roads and elevation data, can be draped over the picture.

Data Acquisition Data Processing

World Files

15.00000000000000.000000000000000.00000000000000-15.000000000000304792.500000000 4891807.50000000

30.00000000000000.000000000000000.00000000000000-30.000000000000304800.000000000 4891800.00000000

World File for 30 meter pixel

RGB, CIR & 143 images

World File for 15 meter pixel

PAN image

LANDSAT Image Process ing and GIS Appl icat ions

By Jake McDonald

When an image is projected in ArcMap, other geographic layers can be overlaid on the image. The first image to the right is the RGB image taken into ArcScene and uses elevation data from the USGS to create a 3-D image. The image above this is the 143 image with roads draped on top.

Color Infra-Red (CIR) Image

GIS Applications

143 with Road Drape

3-D RGB image

8-bit Greyscale

Image

Red

Red

Blue

Blue

Green

Green

Infra-Red

Grey