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Jaruloj Chongstitvatana2301474 Advanced Data Structures 1 Index Structures for Multimedia Data Feature-based Approach
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2301474 Advanced Data Structures2 Jaruloj Chongstitvatana 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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2301474 Advanced Data Structures3 Jaruloj Chongstitvatana Queries for Multimedia Data Point queries Given a data, find the exact match Range queries Given a data, find similar data within a range Nearest-neighbor queries Given a data, find the most similar data
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2301474 Advanced Data Structures4 Jaruloj Chongstitvatana 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 element For geometric data: slope of segments of perimeter For text descriptor: number of each keyword
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2301474 Advanced Data Structures5 Jaruloj Chongstitvatana 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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2301474 Advanced Data Structures6 Jaruloj Chongstitvatana Similarity Queries Point queries Given 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 queries Given an object x, find an object y such that (x,y) ≤ (x,z) for any object z in the database.
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2301474 Advanced Data Structures7 Jaruloj Chongstitvatana Distance Measure Euclidean distance Manhattan distance Maximum distance Weighted Euclidean distance Ellipsoid distance (x,y) = ( i=1,…,d (x i -y i ) 2 ) 1/2 (x,y) = i=1,…,d |x i -y i | (x,y) = max i=1,…,d |x i -y i | (x,y) = ( i=1,…,d w i (x i -y i ) 2 ) 1/2 (x,y) = (x-y) T W (x-y)
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2301474 Advanced Data Structures8 Jaruloj Chongstitvatana Other Similarity Queries k-Nearest-neighbor queries Given an object x and an integer k, find k objects y 1, y 2,…, y k, such that, for i=1, 2, …, k, (x,y i ) ≤ (x,z) for any other object z in the database. Approximate nearest-neighbor queries Approximate k-nearest-neighbor queries
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2301474 Advanced Data Structures9 Jaruloj Chongstitvatana Range Queries On k-d-B trees Grid files Quad trees R-trees Already discussed.
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2301474 Advanced Data Structures10 Jaruloj Chongstitvatana Nearest-neighbor Queries On k-d-B trees Grid files Quad trees R-trees Let’s discuss.
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