jaruloj chongstitvatana2301474 advanced data structures 1 index structures for multimedia data...

Jaruloj Chongstitvatana 2301474 Advanced Data Structures 1

Index Structures for Multimedia Data

Feature-based Approach

2301474 Advanced Data Structures 2Jaruloj Chongstitvatana

Multimedia Data

Feature-based approach

Image/Voice data Sequence data Geometric data Text descriptor

Examples

Movies, music Gene sequence Shape (CAD) Documents


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


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


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.


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.


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)


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


Range Queries

On k-d-B trees Grid files Quad trees R-trees

Already discussed.


Nearest-neighbor Queries

On k-d-B trees Grid files Quad trees R-trees

Let’s discuss.