Method and apparatus of computing location of safe exit for moving range query in road network

A method of providing a range query result, comprising:

• requesting, by a processor, a range query for an object located within a query distance from a first location, to a server;
• receiving, at the processor, a first range query result based on the first location and information about a safe region that provides a result identical to the first range query result based on the first location, wherein the first range query result depends on direction information associated to a road segment located within the query distance from the first location;
• determining, by the processor, a current location of a moving client terminal;
• providing, by the processor, the first range query result to a user as a range query result for the current location if the current location of the moving client terminal is included in the safe region;
• extracting, by the processor, locations of safe exits, which are boundary points of the safe region, on a road;
• transmitting, by the processor, information about the extracted locations of the safe exits on the road to the client terminal;
• monitoring, by the processor, a change in a value assigned to at least one road segment;
• determining, by the processor, whether the change in the value assigned to the at least one road segment influences a previous computational result of the safe region;
• and
• recalculating, by the processor, the safe region using the changed value assigned to the at least one road segment if the change in the value assigned to the at least one road segment influences the previous computational result of the safe region.

An apparatus for computing a range query result, comprising a processor configured to:

• receive a request for a range query for an object, located within a query distance from a query location, from a client terminal;
• compute a first distance from the query location to the object by taking account of direction information associated to road element located within the query distance from the query location;
• compute a first range query result based on the query location in response to the request for a range query, wherein the first range query result depends on the first distance and the direction information;
• compute a safe region that provides a range query result identical to the first range query result based on the query location;
• transmit the first range query result based on the query location and information about the safe region to the client terminal;
• extract locations of safe exits, which are boundary points of the safe region, on a road;
• transmit information about the extracted locations of the safe exits on the road to the client terminal;
• compute a second range query result based on at least one intersection adjacent to the query location;
• compare the second range query result based on the at least one intersection adjacent to the query location and the first range query result based on the query location;
• and
• determine whether a safe exit, which is a boundary point of the safe region, is present between the at least one intersection adjacent to the query location and the query location using a result of the comparison.

An apparatus for providing a range query result, comprising a processor configured to:

• request a range query for an object located within a query distance from a first location, to a server;
• receive a first range query result based on the first location and information about a safe region that provides a result identical to the first range query result based on the first location, wherein the first range query result depends on direction information associated to a road segment located within the query distance from the first location;
• determine a current location of a moving client terminal;
• provide the first range query result based on the first location to a user as a range query result for the current location, if the current location of the moving client terminal is included in the safe region;
• extract locations of safe exits, which are boundary points of the safe region, on a road;
• transmit information about the extracted locations of the safe exits on the road to the client terminal;
• monitor a change in a value assigned to at least one road segment;
• determine whether the change in the value assigned to the at least one road segment influences a previous computational result of the safe region;
• and
• recalculate the safe region using the changed value assigned to the at least one road segment if the change in the value assigned to the at least one road segment influences the previous computational result of the safe region.