Jaruloj Chongstitvatana2301474 Advanced Data Structures 1 Index Structures for Multimedia Data...
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Jaruloj Chongstitvatana 2301474 Advanced Data Structures 1
Index Structures for Multimedia Data
Feature-based Approach
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Multimedia Data
Feature-based approach
Image/Voice data Sequence data Geometric data Text descriptor
Examples
Movies, music Gene sequence Shape (CAD) Documents
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Queries for Multimedia Data
Point queriesGiven a data, find the exact match
Range queriesGiven a data, find similar data within a range
Nearest-neighbor queriesGiven a data, find the most similar data
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Feature Transformation
Mapping from an object to a d-dimensional vector, called a feature vector.
What is this mapping function?For image data: color histogram, etc.For sequence data: number of each elementFor geometric data: slope of segments of
perimeterFor text descriptor: number of each keyword
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Similarity Measure: distance function
Given 2 data objects x and y. Let (x,y) be the distance function.
(x,y) indicates the similarity between data x and y.
Usually (x,y) is based on a distance between the feature vectors of x and y.
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Similarity Queries
Point queriesGiven an object x, find any object y such that
(x,y)=0. Range queries
Given an object x and a threshold , find any object y such that (x,y) < .
Nearest-neighbor queriesGiven an object x, find an object y such that
(x,y) ≤ (x,z) for any object z in the database.
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Distance Measure
Euclidean distance
Manhattan distance
Maximum distance
Weighted Euclidean distance
Ellipsoid distance
(x,y) = (i=1,…,d (xi-yi)2 )1/2
(x,y) = i=1,…,d |xi-yi|
(x,y) = max i=1,…,d |xi-yi|
(x,y) = (i=1,…,d wi (xi-yi)2 )1/2
(x,y) = (x-y)T W (x-y)
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Other Similarity Queries
k-Nearest-neighbor queriesGiven an object x and an integer k, find k
objects y1, y2,…, yk, such that, for i=1, 2, …, k, (x,yi) ≤ (x,z) for any other object z in the database.
Approximate nearest-neighbor queries Approximate k-nearest-neighbor queries
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Range Queries
On k-d-B trees Grid files Quad trees R-trees
Already discussed.
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Nearest-neighbor Queries
On k-d-B trees Grid files Quad trees R-trees
Let’s discuss.