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Need both of the
following:
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Make
sure your detector is invariant
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Harris is
invariant to translation and rotation
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Scale is trickier
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common approach
is to detect features at many scales using a
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Gaussian pyramid
(e.g., MOPS)
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More
sophisticated methods find “the best scale” to represent
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each feature
(e.g., SIFT)
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2. Design an invariant feature descriptor
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A descriptor
captures the information in a region around the
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detected feature
point
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The simplest
descriptor: a square window of
pixels
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What’s this
invariant to?
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Let’s look at
some better approaches…
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