Directions: Compositing
 

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Introduction

Using Remote Sensing

  1. Obtaining
  2. Linking
  3. Subsetting
  4. Compositing
  5. False coloring
  6. Ratioing
  7. Supervised classification

Examples

Pre-post test

Directions for making a composite LANDSAT Image

These directions are used to combine two images so that differences can be accentuated.
Background requirements: Downloaded and familiarity with the free MultiSpec© software and tutorial (See
http://cobweb.ecn.purdue.edu/~biehl/MultiSpec/Index.html) and a basic understanding of satellite images (i.e. bands, false color imaging, resolution). See: A Guide For Teachers http://www.geo.utep.edu/pub/keller/AGuideforTeachers.html

You must have downloaded and linked bands of the two images you want to study and have reformatted, renamed, and saved them.  One of the images should be a subsetted image. These directions will help you link a second image to the first subsetted image so that changes between the two images can be observed. Refer to the direction sheets titled: Directions For Obtaining Ohio LANDSAT Images, Directions for linking LANDSAT single band images, and Directions for Subsetting Single Images of downloaded LANDSAT images. Failure to follow these steps results in unaligned linked images.

  1. Open MultiSpec.
  2. Click File. Click Open Image. Select your subset image. Click OK on next 2 screens. 
  3. Click File. Click Open Image. Select the second image. Wait until it loads.
  4. Bring your subset image forward (click on the blue top bar)
  5. Click Edit. Click “select all image”.
  6. Click Edit. Click “Edit selection rectangle” Click Units. Select Lat-long. CHECK BOX LABELED “apply to all image windows” Click on ok. If a window pops up saying minimum or maximum limits are exceeded, check ok. Increase or decrease the lat-long numbers a small amount until the pop ups stop. There should be a rectangle drawn on the second image.
  7. Bring the second image to the front. Click Processor. Select Reformat. Select Change Image File Format. Click Ok in next screen. Rename your file with a descriptive name and extension .tif such as ss Toledo b1234567 May 06.tif  Wait until the image is reformatted (100% complete)
  8. Close both images.
  9. Click File. Click Open Image. Select the first subset image (.tif file). Click OK in next screen. Wait.
  10. Click file. Click open image. Select your second subset image. CHECK THE BOX LABELED “link to active window” Click Open. Click cancel in next window.
  11. Click Processor. Select Reformat. Select Change Image File Format. Click Ok in next screen. Rename your file with a descriptive name and extension .tif such as: composite ss Toledo may 00 06 b1234567.tif  Click OK. Wait.
  12. Close images. To Check if it worked: Click File, Click Open Image. Select composite image. Click Processor. Select “Display image” in Type box “select side by side channels”. Click the small mountain in the menu bar several times to reduce the images. If the process worked, you will have 14 numbered black and white images for b1234567 from each image.