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Suppose we are
comparing two images I1 and I2
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I2 may
be a transformed version of I1
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What kinds of
transformations are we likely to encounter in
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practice?
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We’d like to
find the same features regardless of the
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transformation
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This is called
transformational invariance
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Most feature
methods are designed to be invariant to
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Translation, 2D
rotation, scale
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They can usually
also handle
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Limited 3D
rotations (SIFT works up to about 60 degrees)
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Limited affine
transformations (some are fully affine invariant)
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