# Lecture-15 - is a local maximum in a 12 by 12 overlapping...

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1 Lecture-15 Quad Trees, Chain Code, Shape number & Moravec’s interest operator Quad Trees • Data structure to represent regions • Three types of nodes: gray, black and white • First generate the pyramid, then: • If type of pyramid is black or white then return else – Recursively find quad tree of SE quadrant – Recursively find quad tree of SW quadrant – Recursively find quad tree of NE quadrant – Recursively find quad tree of NW quadrant – Retrun

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2 Chain Code • A simple technique to represent a shape of boundary. • Each directed line segment is assigned a code. • Chain code is integer obtained by putting together the codes of all consecutive line segments. • Shape number is a normalized chain code, which is invariant to translation and rotation.
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4 Moravec’s Interest Operator Algorithm • Compute four directional variances in horizontal, vertical, diagonal and anti- diagonal directions for each 4 by 4 window. • If the minimum of four directional variances

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Unformatted text preview: is a local maximum in a 12 by 12 overlapping neighborhood, then that widow (point) is interesting. 5 6 ∑∑ = = + + +-+ + = 3 2 2 )) , 1 ( ) , ( ( j i h j y i x P j y i x P V ∑∑ = = + + +-+ + = 2 3 2 )) 1 , ( ) , ( ( j i v j y i x P j y i x P V ∑∑ = = + + + +-+ + = 2 2 2 )) 1 , 1 ( ) , ( ( j i d j y i x P j y i x P V ∑∑ = = + +-+-+ + = 2 3 1 2 )) 1 , 1 ( ) , ( ( j i a j y i x P j y i x P V )) , ( ), , ( ), , ( ), , ( min( ) , ( y x V y x V y x V y x V y x V a d v h = = therwise local y x ifV y x I max ) , ( 1 ) , ( 7 Books by Hans Moravec • Robot Rover Visual Navigation • Mind Children: The future of Robot and Human Intelligence • Robot, Being – Website http://www.frc.ri.cmu.edu/~hpm/ 8 Cart under SAIL 1979 and 1997 3D Maps from stereo 9 NAVLABS Beast 10 Universal Delivery Potsdam 11 Home Vacuum Cleaning Robot (Dustbot) Home Vacuum Cleaning Robot (Dustbot) 12 13...
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## This note was uploaded on 06/12/2011 for the course CAP 5415 taught by Professor Staff during the Fall '08 term at University of Central Florida.

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Lecture-15 - is a local maximum in a 12 by 12 overlapping...

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