KR100891039B1 - Structure and method of indexing for processing of moving object queries in road network databases - Google Patents

Abstract

The present invention relates to an indexing structure and method for querying a mobile object in a road network. The present invention relates to a road network management index for managing a road network for processing coordinate-based queries, and trajectory information of a moving object for processing a trajectory-based query. It includes a trajectory storage structure that manages the trajectory storage structure, a trajectory storage structure management index that manages the trajectory storage structure, and a moving object management index that manages the moving objects to process non-spatial queries. This is great and can be useful in real environments like cars moving on the road.

Moving object, moving object database, spatiotemporal index, query processing

Description

Structure and method of indexing for processing of moving object queries in road network databases}

1 is a schematic diagram of an indexing structure for query processing of a mobile object in a road network according to the present invention.

2 is a flowchart for processing a coordinate-based query according to an embodiment of the present invention.

3 is a flowchart for processing a trajectory based query according to an embodiment of the present invention.

4 is a flowchart for processing a complex query according to an embodiment of the present invention.

5 is a flowchart for processing a non-spatial query according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: road network management index 20: trajectory storage structure management index

30: moving object management index 40: trajectory storage structure

The present invention relates to an indexing structure and method for querying a mobile object in a road network, and more particularly, to process various user queries in a mobile object database in which moving information is stored over time. An indexing structure and method for query processing of mobile objects in a road network that proposes an effective index construction method.

A road network is a space where constraints exist in the space in which a moving object moves. It is expressed as a set of segments and connection points. The segment is represented by a straight line with a start point and an end point, and may indicate the position of the moving object, the moving direction of the moving object, the speed, and the speed change. A connection point is a point at which segments are connected, and refers to an intersection on an actual road.

Conventional indexing techniques for supporting user search in road networks include FNR-tree and MON-tree.

The FNR-tree organizes segments of the road network into two-dimensional R-trees, and each leaf node stores a pointer to the one-dimensional R-tree. This one-dimensional R-tree stores the moving objects that existed in the road segment, the time they came in and the time they went out. Because there is little change in road network, two-dimensional R-trees are rarely updated once created. On the other hand, the one-dimensional R-tree is frequently updated according to the movement of the moving object. FNR-Tree focuses on improving the performance of coordinate-based queries on the network.

The MON-tree consists of two R-trees in a structure similar to that of the FNR-tree. The first R-tree is called the parent index and the second R-tree is called the child index. The higher index indexes the road network, which differs from the FNR-tree in that it consists of R-trees in polylines. Multi-segment refers to a series of road segments as one long segment. Each entry of the leaf node of the upper index stores a pointer to the lower index. The lower index is a two-dimensional R-tree that stores the time intervals stayed in the multi-segments where the moving objects are located and their relative positions.

Since the conventional FNR-tree and MON-tree target only coordinate-based queries, there is a big problem that query processing cannot be performed on various user queries such as trajectory-based queries and complex queries.

The present invention has been proposed to solve the above problems, and effectively handles various user queries such as coordinate-based queries, trajectory-based queries, and complex queries in a moving object database in which moving information is stored over time of moving objects. An object of the present invention is to provide an indexing structure and an indexing method for querying a mobile object in a road network.

Indexing structure for query processing of a moving object in the road network according to the present invention for achieving the above object, to process the road network management index, trajectory-based query for managing the road network to process the coordinate-based query And a trajectory storage structure for managing trajectory information of the moving object, a trajectory storage structure management index for managing the trajectory storage structure, and a moving object management index for managing the moving object for processing a non-spatial query.

In addition, in the indexing structure for query processing of the moving object in the road network according to the present invention, the terminal node of the road network management index includes the ID of the road segment, the coordinates of the MBR including the road segment, And a pointer to an index for managing the directionality and the trajectory information.

In addition, in the indexing structure for query processing of a moving object in a road network according to the present invention, the trajectory storage structure is composed of a plurality of blocks, and in one block, IDs of a moving object and one moving object are several. And a previous block indication pointer indicating the previous block of the trajectory when stored as a block, a next block indicating pointer indicating the next block in which the trajectory of the moving object is stored, and segment information constituting the trajectory of the moving object. It is.

In addition, in the indexing structure for query processing of a moving object in the road network according to the present invention, the segment information includes an ID of the corresponding segment, a time when the moving object enters the corresponding segment, a moving object at the speed of the corresponding segment, and a moving object. It characterized in that it contains the direction of movement of.

In addition, in the indexing structure for query processing of a moving object in the road network according to the present invention, the trajectory storage structure management index is a moving object existing in the segment at the time when the moving object enters the segment, or when the moving object enters the segment. And a block offset for finding the position of the corresponding segment in the block in which the trajectory ID and the trajectory information are stored.

In addition, in the indexing structure for query processing of a moving object in a road network according to the present invention, the terminal node of the moving object management index may be configured to search for an ID of a moving object and a trajectory of the moving object. It includes a pointer to the storage structure is stored.

On the other hand, the indexing method for the coordinate-based query processing of the moving object in the road network according to the present invention, (a) accessing the road network management index, (b) determines whether there is a road segment ID corresponding to the query region (C) accessing an index for managing a trajectory storage structure along a pointer of a segment when a road segment ID exists in step (b); and (d) presence of a moving object ID at query time in the segment. Determining whether the mobile object ID exists in step (d), and returning the ID of the mobile object to the user and ending the query processing.

On the other hand, the indexing method for trajectory-based query processing of the moving object in the road network according to the present invention, (a) accessing the road network management index, (b) determines whether there is a road segment ID corresponding to the query region (C) accessing an index for managing a trajectory storage structure along a pointer of a segment when a road segment ID exists in step (b); and (d) presence of a moving object ID at query time in the segment. Determining whether or not, (g) accessing the block in which the trajectory storage structure is stored through the block offset of the moving object ID, and (h) determining the segment ID of the trajectory within the query time through the segment information of the trajectory storage structure. Searching, and (i) returning the mobile object ID and the segment IDs of the trajectory to the user and terminating the query processing.

Meanwhile, an indexing method for processing a complex query of a moving object in a road network according to the present invention includes: (a) accessing a road network management index, and (b) determining whether a road segment ID corresponding to a query region exists. (C) accessing an index for managing a trajectory storage structure along a pointer of a segment when a road segment ID exists in step (b); and (d) whether a moving object ID exists at a query time in the segment. Determining (g) accessing the block in which the trajectory storage structure is stored through the block offset of the moving object ID; and (k) determining the trajectory segment ID within a specific time after the query time through the segment information of the trajectory storage structure. Searching, and (l) returning the mobile object ID and the segment IDs of the trajectory to the user and terminating the query processing.

In addition, in the indexing method for querying a moving object in a road network according to the present invention, when there is no segment ID or a moving object ID in step (b) or (d), a road corresponding to a query region, respectively The method may further include informing that there is no segment or that there is no moving object moving to the region, and stopping the query processing.

Meanwhile, in the road network according to the present invention, the indexing method for processing a non-spatial query of a moving object includes (m) accessing a moving object management index, and (n) determining whether a moving object ID corresponding to the query exists. Step (o) accessing a trajectory storage structure along the pointer of the moving object when the ID of the moving object exists in step (n); and (p) location of the moving object at query time through segment information. Searching for, and (q) returning segment information corresponding to the query time to the user and ending the query processing.

In addition, in the indexing method for querying a moving object in a road network according to the present invention, if there is no moving object ID corresponding to the query in step (n), the user does not have a moving object corresponding to the query. The method may further include informing and stopping the query processing.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a schematic diagram of an indexing structure for query processing of a mobile object in a road network according to the present invention.

Indexing structure according to the present invention is largely composed of three structures.

Firstly, a road network management index (10) for managing road networks to process coordinate-based queries, and a second path trajectory storage structure (40) for managing trajectory information to process trajectory-based queries and a trajectory storage structure management index ( 20) Third, a mobile object management index 30 that manages mobile objects to process non-space queries is composed.

Here, the user query for processing in the present invention targets almost all queries proposed up to now, and the types of the queries are as follows.

The coordinate-based query is a query for searching for moving objects satisfying a coordinate condition in a space made of space-time three-dimensional space. According to this coordinate condition, it is divided into point query and region query.

Point queries retrieve the presence or absence of moving objects associated with a given point in space-time. For example, a query that retrieves whether there was a moving object at coordinates (30, 50) at 3 pm corresponds.

Region queries retrieve the presence or absence of moving objects within a specific region. For example, a query for retrieving moving objects that have existed in an area of 20 to 40 x coordinates and 50 to 80 y coordinates from 2 pm to 3 pm is equivalent. In particular, a query with a zero time interval is called a time-slice query.

In addition, the trajectory-based query may be divided into a topological query and a navigational query. The topology query is a query that tracks the movement of a moving object trajectory. The topology query searches which road segment the moving object has moved over time. For example, given a query region and time, this is a query that retrieves the movement of a moving object within the given region and time. The navigation query calculates the speed or direction based on the trajectory information of the moving object. For example, a query that calculates the speed at which a particular moving object moves at 3 pm is equivalent.

On the other hand, a combined query is a trajectory-based query for a moving object retrieved through an area query. When a query region is given to perform an area query, the query searches a moving object corresponding to the query region and performs a trajectory-based query on the searched moving object to track the movement of the trajectory for a predetermined time after the query region. For example, a query that retrieves a route for the next hour of moving objects that left a particular region between 7 and 8 today.

Non-spatial queries are queries that ask for movement and past or current positions for a particular moving object. For example, a query that searches where a particular car was at 9 o'clock.

Referring to FIG. 1, the road network management index 10 managing the road network may be configured as an R * -tree.

The index used to manage the road network manages the road network on a segment basis.

The terminal node of this index is composed of <seg_id, MBR, orientation, and ptr>.

Here, seg_id represents an ID of a segment, and MBR represents a coordinate of a minimum bounding rectangle including a segment.

In addition, the orientation represents the orientation of the segment and has a 0 or a 1. Finally, ptr is a pointer to an index that manages trajectory information.

The trajectory storage structure management index 20 managing the trajectory information manages the trajectory storage structure 40 in which the movement information of the moving object is stored over time.

As shown in FIG. 1, the trajectory storage structure 40 of the moving object is as follows.

In the moving object, one trajectory may be stored in several blocks.

The one block is composed of <mo_id, prev_block, next_block, seg_info>.

Where mo_id represents the ID of the moving object and prev_block indicates the previous block of the trajectory when the trajectory of one moving object is stored in several blocks.

Similarly, next_block points to the next block where the trajectory is stored. Finally, seg_info represents information of segments constituting the trajectory of the moving object. This seg_info is composed of <seg_id, time, speed, direction>. seg_id represents an ID of a segment, and time represents a time when a mobile object enters the segment. speed indicates the speed in the segment of the moving object, and finally direction indicates information in which direction the moving object has moved.

In order to easily access the trajectory storage structure 40 and process trajectory-based queries, the trajectory storage structure management index 20 that manages the trajectory information described above is used.

The trajectory storage structure management index 20 may be configured as a B + -tree.

The index consists of <time, mo_id, block_offset>, which is an index having a key of the time when the mobile object enters the segment.

Here, time means a time when the moving object enters the segment. mo_id is the trajectory ID of the moving object existing in the segment at that time. block_offset means an offset for finding a position of a corresponding segment in a block in which trajectory information is stored.

In the last structure, the moving object management index 30 managing the moving object in order to process the non-spatial query may be configured as a B + -tree. The terminal node of this index has a form of <mo_id, ptr>.

Here, mo_id means the ID of the moving object, and ptr means a pointer indicating a storage structure in which the trajectory of the moving object is stored in order to retrieve the trajectory of the moving object. The trajectory storage structure 40 is accessed through the pointer to process nonspatial queries.

2 is a flowchart for processing a coordinate-based query according to an embodiment of the present invention.

The process of processing a coordinate-based query using the index structure shown in FIG. 1 is as follows.

First, the road network management index 10 is accessed to process the coordinate-based query (S21).

Next, it is determined whether a road segment ID <seg_id> corresponding to the query region exists (S22).

If the road segment ID exists in step S22, the trajectory storage structure management index 20 managing the trajectory storage structure is approached along the pointer <ptr> of the segment (S23).

Next, it is determined whether there is a moving object ID <mo_id> existing at the query time in the corresponding segment (S24).

Finally, if the corresponding moving object ID <mo_id> exists in step S24, the ID of the moving object is returned to the user and the query processing is terminated (S25).

In addition, when the road segment ID corresponding to the query region does not exist in step S22, the user is notified that there is no road segment corresponding to the query region and the query processing is stopped (S26).

In addition, if there is no moving object ID present at the query time in the segment at step S24, the user is notified that there is no moving object moving to the corresponding area at the query time and the query processing is stopped (S27).

3 is a flowchart for processing a trajectory based query according to an embodiment of the present invention.

The process of processing a trajectory based query using the index structure shown in FIG. 1 is as follows.

First, the road network management index 10 is accessed to process the trajectory based query (S31).

Next, it is determined whether a road segment ID <seg_id> corresponding to the query region exists (S32).

If the road segment ID exists in step S32, the trajectory storage structure management index 20 managing the trajectory storage structure is approached along the pointer <ptr> of the segment (S33).

Next, it is determined whether there is a moving object ID <mo_id> existing at the query time in the corresponding segment (S34).

If it is determined in step S34 that there is a moving object ID, the trajectory storage structure management index 20 accesses a block in which the trajectory storage structure is stored through <block_offset> of the moving object ID <mo_id> (S35).

Next, the segment ID of the trajectory belonging to the query time is searched through the segment information <seg_info> of the trajectory storage structure 40 (S36).

Finally, the mobile object ID <mo_id> and the segment ID <seg_id> of the trajectory are returned to the user, and the query processing is terminated (S37).

In addition, when the road segment ID corresponding to the query region does not exist in step S32, the user is notified that there is no road segment corresponding to the query region and the query processing is stopped (S38).

In addition, when there is no moving object ID present at the query time in the corresponding segment in step S34, the user is notified that there is no moving object moving the corresponding region at the query time and the query processing is stopped (S39).

4 is a flowchart for processing a complex query according to an embodiment of the present invention.

The process of processing a complex query using the index structure shown in FIG. 1 is as follows.

 First, the road network management index 10 is accessed to process a complex query (S41).

Next, it is determined whether a road segment ID <seg_id> corresponding to the query region exists (S42).

When the road segment ID exists in step S42, the track storage structure management index 20 managing the track storage structure is approached along the pointer <ptr> of the segment (S43).

Next, it is determined whether there is a moving object ID <mo_id> existing at the query time in the corresponding segment (S44).

If it is determined in step S44 that there is a moving object ID, the trajectory storage structure management index 20 accesses a block in which the trajectory storage structure is stored through <block_offset> of the moving object ID <mo_id> (S45).

Next, the segment ID of the trajectory within the specific time after the query time is searched through the segment information <seg_info> of the trajectory storage structure 40 (S46).

Finally, the mobile object ID <mo_id> and the segment ID <seg_id> of the trajectory are returned to the user, and the query processing is terminated (S47).

In addition, when the road segment ID corresponding to the query region does not exist in step S42, the user is notified that there is no road segment corresponding to the query region and the query processing is stopped (S48).

In addition, when there is no moving object ID present at the query time in the corresponding segment in step S44, the user is notified that there is no moving object moving the corresponding region at the query time and the query processing is stopped (S49).

5 is a flowchart for processing a non-spatial query according to an embodiment of the present invention.

The process of processing a non-spatial query using the index structure shown in FIG. 1 is as follows.

First, the mobile object management index 30 is accessed to process the non-spatial query (S51).

Next, it is determined whether a moving object ID <seg_id> corresponding to the query exists (S52).

If the ID of the moving object exists in step S52, the trajectory storage structure 40 is accessed along the pointer <ptr> of the moving object (S53).

Next, the position of the corresponding moving object is searched at the query time through the segment information <seg_info> (S54).

Finally, the segment information <seg_info> corresponding to the query time is returned to the user, and the query processing is terminated (S55).

In addition, when there is no moving object ID corresponding to the query in step S52, the user is notified that there is no moving object corresponding to the query, and the query processing is stopped (S56).

As described above, according to the index structure shown in FIG. 1, various queries of a user accessing a moving object database based on a road network can be effectively processed.

According to the present invention, since various user queries can be processed in a road network based space, it can be usefully used in a real environment such as a car moving on a road.

In addition, query processing performance is excellent because various indexes are used for user query processing.

Although the present invention has been described in detail only with respect to the specific embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications belong to the appended claims. .

Claims (12)

A road network management index for managing a road network to process coordinate-based queries; A trajectory storage structure that manages trajectory information of a moving object to process trajectory-based queries; A trajectory storage structure management index for managing the trajectory storage structure; And It includes a moving object management index for managing a moving object for processing a non-spatial query, the trajectory storage structure is composed of a plurality of blocks, the one block ID of the moving object, the trajectory of one moving object Includes a previous block indication pointer indicating the previous block of the trajectory, a next block indicating pointer indicating the next block in which the trajectory of the moving object is stored, and segment information constituting the trajectory of the moving object when stored as four blocks. Segment information includes the ID of the segment, the time the mobile object entered the segment, the moving speed of the segment of the moving object, and the moving direction information of the moving object. Indexing structure. The method of claim 1, The terminal node of the road network management index includes a pointer indicating an ID of the road segment, coordinates of the MBR including the road segment, direction of the segment, and an index managing the trajectory information. Indexing structure for querying mobile objects in network. delete delete The method of claim 1, The locus storage structure management index, And a block offset for finding the position of the segment in the block in which the moving object enters the segment, the trajectory ID of the moving object existing in the segment at the time the moving object enters, and the trajectory information is stored. Indexing Structure for Querying Mobile Objects in Road Networks. The method of claim 1, The terminal node of the moving object management index includes a pointer indicating a storage structure in which the trajectory of the mobile object is stored in order to retrieve the ID of the mobile object and the trajectory of the mobile object. Indexing structure for query processing of objects. delete (a) accessing a road network management index; (b) determining whether a road segment ID corresponding to the query region exists; (c) accessing an index managing a trajectory storage structure along a pointer of the segment when the road segment ID exists in step (b); (d) determining whether a mobile object ID exists at the query time in the segment; (g) accessing a block in which the trajectory storage structure is stored through the block offset of the mobile object ID; (h) In the trajectory storage structure, the segment belonging to the query time through segment information including the ID of the segment, the time that the moving object entered the segment, the moving speed of the moving object in the segment, and the moving direction of the moving object. Retrieving a segment ID; And (i) returning the moving object ID and the segment IDs of the trajectory to the user and ending the query processing. (a) accessing a road network management index; (b) determining whether a road segment ID corresponding to the query region exists; (c) accessing an index managing a trajectory storage structure along a pointer of the segment when the road segment ID exists in step (b); (d) determining whether a mobile object ID exists at the query time in the segment; (g) accessing a block in which the trajectory storage structure is stored through the block offset of the mobile object ID; (k) In the trajectory storage structure, the segment information including the ID of the segment, the time when the moving object enters the segment, the moving speed of the moving object in the corresponding segment, and the moving direction of the moving object is displayed within a specific time after the query time. Retrieving a trajectory segment ID; And (l) returning the moving object ID and the segment IDs of the trajectory to the user and ending the query processing. delete (m) accessing a moving object management index; (n) determining whether a mobile object ID corresponding to the query exists; (o) accessing the trajectory storage structure along the pointer of the moving object when the ID of the moving object exists in step (n); (p) Query time through segment information in the trajectory storage structure through segment information including the ID of the segment, the time when the moving object entered the segment, the moving speed of the moving object in the segment, and the moving direction information of the moving object. Retrieving the location of the corresponding moving object; (q) returning the segment information corresponding to the query time to the user and ending the query processing. delete

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