Vision & RecognitionVision & Recognition

• From a different direction

• At different times, particularly if it has been modified in the interval

• In different light

A particular object may have different visual attributes when viewed:

ObservationsObservations

• Be able to distinguish between different objects with the same appearance

• Be able to recognize the same object viewed from different directions or in different light

• Be able to recognize the same object after modification

• Be able to distinguish between an object and its reflection

ObjectivesObjectives

•Pattern recognition

•Robot vision

•Remotely operated devices

•Security related software

•Disease Diagnosis

ApplicationsApplications

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The Minimum 3-D Feature Set The Minimum 3-D Feature Set

Two cubes of the same color are indistinguishable.

Cubes are distinguished by color, color count and color position

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The Minimum 3-D Feature Set The Minimum 3-D Feature Set

2 sides color ‘A’

2 sides color ‘B’

Maximum of 2 distinguishable cubes

Cubes are distinguished by color, color count and color position

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The Minimum 3-D Feature SetThe Minimum 3-D Feature Set

3 sides color ‘A’

3 sides color ‘B’

Maximum of 2 distinguishable cubes.

2 colors -> 8 cubesCubes are distinguished by color, color count and color position

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The Minimum 3-D Feature SetThe Minimum 3-D Feature Set

Like color sides opposite vs. like colored sides adjacent.

3 colors -> 27 cubes

Cubes are distinguished by color, color count and color position

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With 4 color cubes, pattern With 4 color cubes, pattern breaks. breaks.

We would expect 4We would expect 433 = 64 = 64

But we only get 42 But we only get 42 distinguishable cubes.distinguishable cubes.

Why? ---> Rotations !Why? ---> Rotations !

The Minimum 3-D Feature SetThe Minimum 3-D Feature Set

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Rotations and ReflectionsRotations and Reflections

The Eight Queens Problem

for (i = 0; i < 8; i++){

ok = 1;

pNextPair->column = i;

pPairOnTop = pTop;

while (ok = 1 && pPairOnTop != NULL){

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One left succeeds, all others fail to find solution

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Same object viewed from different angles

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Q Q Q Q QQ Q Q Q Q QHow do we determine which patterns are

significant?

12 partitions

12 distinct solutions

Why not 96 (= 12 x 8) permutations?

The answer is that one of our partitions contains only 4 "aliases" because the solution is diagonally symmetric

Permutations of the solution Permutations of the solution vectorsvectors

Shape detection Shape detection algorithmsalgorithms

Without color…

example universe:

assembly-line where all parts are uniformly steel-colored

Shape detection Shape detection algorithmsalgorithms

Edge detection

Using changes in reflectivity

Shape detection Shape detection algorithmsalgorithms

Edge detection

Edges can intersect with planes, or air

Is the background the same object or a different one?

Shape data structShape data structuresures

Corners have “more information” per point

Collection of points and relative distances

Collection of lines and intersections

Collections of shape primitives

Shape data structShape data structuresures

Corners can be used to define

Collections of edges and intersections

Or boundaries of planes

Shape data structShape data structuresures

Skeletons…AKA

Wire-Frames

Advantage… easier to morph

Shape data structShape data structuresures

Volume filling shape primitives

advantage: can easily calculate volume as sum of primitives’ volume

There are many applications...There are many applications...

Volumes of research…Volumes of research…

And many areas yet And many areas yet unexplored...unexplored...

Vision & RecognitionVision & Recognition

Thank you.Thank you.