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Using Blocks of Skewers for Faster Computation of Pixel Purity Index.

PB2001105678

Publication Date	2000
Personal Author	Theiler, J.; Lavenier, D. D.; Harvey, N. R.; Perkins, S. J.; Szymanski, J. J.
Page Count	14
Abstract	The pixel purity index (PPI) algorithm proposed by Boardman, et al identifies potential endmember pixels in multispectral imagery. The algorithm generates a large number of skewers (unit vectors in random directions), and then computes the dot product of each skewer with each pixel. We report on a variant of the PPI algorithm in which blocks of B skewers are considered at a time. From the computation of B dot products, one can produce a much larger set of derived dot products that are associated with skewers that are linear combinations of the original B skewers. Since the derived dot products involve only scalar operations, instead of full vector dot products, they can be very cheaply computed.
Keywords	Remote sensing Pixels Purity Algorithms Vectors(Mathematics) Skewers
Source Agency	Technical Information Center Oak Ridge Tennessee
NTIS Subject Category	46C - Optics & Lasers 48C - Natural Resource Surveys
Corporate Authors	Los Alamos National Lab., NM.; California Univ., Berkeley.; Department of Energy, Washington, DC.
Supplemental Notes	Submitted to SPIE Conference Session AM 104 Imaging Spectrometry VI July 30 to August 4, 2000, San Diego, CA. Prepared in cooperation with California Univ., Berkeley. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200117
Contract Number	DOE-W-7405-ENG-36

Using Blocks of Skewers for Faster Computation of Pixel Purity Index.

Using Blocks of Skewers for Faster Computation of Pixel Purity Index.
PB2001105678

Publication Date	2000
Personal Author	Theiler, J.; Lavenier, D. D.; Harvey, N. R.; Perkins, S. J.; Szymanski, J. J.
Page Count	14
Abstract	The pixel purity index (PPI) algorithm proposed by Boardman, et al identifies potential endmember pixels in multispectral imagery. The algorithm generates a large number of skewers (unit vectors in random directions), and then computes the dot product of each skewer with each pixel. We report on a variant of the PPI algorithm in which blocks of B skewers are considered at a time. From the computation of B dot products, one can produce a much larger set of derived dot products that are associated with skewers that are linear combinations of the original B skewers. Since the derived dot products involve only scalar operations, instead of full vector dot products, they can be very cheaply computed.
Keywords	Remote sensing Pixels Purity Algorithms Vectors(Mathematics) Skewers
Source Agency	Technical Information Center Oak Ridge Tennessee
NTIS Subject Category	46C - Optics & Lasers 48C - Natural Resource Surveys
Corporate Authors	Los Alamos National Lab., NM.; California Univ., Berkeley.; Department of Energy, Washington, DC.
Supplemental Notes	Submitted to SPIE Conference Session AM 104 Imaging Spectrometry VI July 30 to August 4, 2000, San Diego, CA. Prepared in cooperation with California Univ., Berkeley. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200117
Contract Number	DOE-W-7405-ENG-36