Accommodating Hybrid Retrieval in a Comprehensive Video Data(3)

(a.2)

Segmented

video &

Domain

knowledge(a.3)Segmented

video tree(d.3)View ofvideoscenes

(c.2)Features(d.2)Target scene

EDICS

S = <A, M, X>

where A is a set of scene attributes, M is a set of scene methods, and X is a set of the Feature-Videoassociations:

X = {<Fi : Vi: [STi]> | 1 ≤ i ≤ n}

where Fi is a feature, and Vi is a set of video objects that carry the feature within the scene, and STi is a ST-Feature which is optionally included in the Feature-Video association. ST-Feature is used when an imageobject can be identified from the video objects and when an image object is represented by a ST-Featurewhich contains a set of “Position and Frame numbers”, which means there is a movement of the objectconcerned. A feature Fi can be described as follows:

Fi = <A’, M’>

where A’ and M’ are a set of attributes and methods defined by the feature Fi; these attributes and methodsare applicable to the video players of the feature. In our Video DBMS, a feature is the same as a semanticdescriptor (a glossary term) that is of interest to end-users.For video applications, an important concept to support is Table of Contents (ToC) which describes thestructural as well as sequencing relationships of video data within a video program. Within a Scene-Feature-Video association, the video objects linked by the feature should form a subset of the constituents includedby the associated scene. In order to support ToC in CCM, the notion of scene is extended by defining atemporal scene St as follows:

St = <A, M, X, T>

where A and M denote attributes and methods defined by the scene St respectively, X is a set of the Feature-Video associations, and T is a template of showing the temporal ordering of the video objects in the scene St.In CCM/ST, two kinds of time dimension in temporal databases: (valid-time and user-defined time) arechosen to be supported due to their applicability to video data. Valid-time concerns the time a fact was truein reality; User-defined time (such as birthdate) provides a new data type (e.g., Date-time) to the user

[TCG+93]. In addition, in order to provide a more flexible way to users, CCM/ST is designed to supportvalid-time at both “Object level” and “Attribute level” [TCG+93], as shown in Table 1. Therefore, CCM/STcan store the past histories and future plans of scenes and features, and thus can provide different versions ofa video program.Time dimension

Valid-time

Valid-time

Valid-time

User-defined timeLifespanObject levelAttribute levelAttribute levelAttribute levelAssociated objectScene / FeatureSceneFeatureScene / FeatureAssociated object componentAttribute, Method, Feature-Video association, ToCAttribute, MethodAttribute

Table 1. Time dimensions supported by CCM/ST

There are several types of temporal functions and operators, e.g. interval specification functions, intervalordering functions, interval ordering operators, and interval comparison operators [SHC98, VTS98]. Some

EDICS

temporal functions adopted in CCM/ST are shown in Table 2 and Table 3. Besides, the Interval orderingoperators are extended from seven to nine operators as shown in Table 4. As the Interval comparisonoperators are used to compare the temporal relationships between two explicit or implicit time/frameintervals, the result of the comparison is either true or false. These operators are used on ToC and Valid-time,the same way as the Interval ordering operators.Function

F_INTERVAL()

VT_INTERVAL()

VALID()

DURATION()

DATE()

INTERVAL()ReturnsFrame interval of video objectsValid-time interval of a temporal instanceCurrent valid elementDuration of frame/valid-time intervalDate instant objectDate interval objectUsed OnToCValid-timeValid-timeToC, Valid-timeValid-timeValid-time

Table 2. Interval specification functions

Function

FIRST()

LAST()

NTH()

PREV()

NEXT()ReturnsFirst elementLast elementThe Nth position of elementPrevious elementNext elementUsed OnToC, Valid-timeToC, Valid-timeToC, Valid-timeToC, Valid-timeToC, Valid-time

Table 3. Interval ordering functions

In order to support spatial semantics of video data, the following spatial functions and operators have beenintroduced in CCM/ST.

(A) Spatial functions = {TOP(), BOTTOM(), LEFT(), RIGHT(), MIDDLE()}

(B) Spatial operators for horizontal dimension = {LEFT, H_MIDDLE, RIGHT}

Spatial operators for vertical dimension = {TOP, V_MIDDLE, BOTTOM}

EDICS

(C) As in [NSN95], the 1-D operators can be used in pairs to form 2-D ones for identifying objects in bothhorizontal and vertical dimensions. Such 2-D operators can be used to specify queries such as “whichobject is at TOP_LEFT" within a specified Frame contained in a SCENE, etc.

3.1.2 CAROL/ST: a query language supporting spatial and temporal primitives

VideoMAP+ has a query language (CAROL/ST) which is devised based on CCM /ST features. Fiveprimitive video retrieval functions have been supported, namely:

select scenes/features/videos by their attribute restrictions

select video players (video objects) by scene’s restriction

select scenes by their features’ restrictions

select features by their scenes’ restrictions

select scenes by their video players’ restrictions

In addition, CAROL/ST provides a set of expressive spatial and temporal primitives. These temporal andspatial operators are introduced based on CCM/ST model; the following query examples demonstrate howthey work.

(A) Example: Consider that a user wants to retrieve all the video objects about “SportsNews” before a given date(say, today). The query can be specified by the following CAROL/ST statement (x is a set of scene objects)φ:

SELECT x FROM SCENE y …… 此处隐藏：5885字，全部文档内容请下载后查看。喜欢就下载吧 ……