Landmark search apparatus, electronic apparatus and imaging apparatus having the same, and landmark search method

1. A landmark search apparatus for retrieving landmarks around an object, comprising:

a position obtaining unit configured to obtain a current position of the object;

a first storage unit configured to store landmark information including a name of a landmark and position information of the landmark related to the name;

an retrieving unit configured to configured to retrieve the landmark information from the first storage unit based on the obtained current position;

a second storage unit configured to store the retrieved landmark information as retrieved landmark information; and

a determining unit configured to determine whether the retrieved landmark information is valid based on: i) the current position of the object; ii) a previous position of the object at a time of storing the retrieved landmark information in the second storage unit; iii) a first distance between the previous position and a farthest landmark from the previous position in landmarks indicated by the landmark information stored in the second storage unit; and iv) a second distance between the previous position and a landmark which is N-th farthest from the previous position in the landmarks indicated by the landmark information stored in the second storage unit, N being a predetermined number,

wherein the determining unit determines whether a moving distance of the object from the previous position to the current position is more than a half of the first distance minus the second distance to determine whether the retrieved landmark information is valid.

2. The landmark search apparatus according to claim 1 , wherein the retrieving unit controls, based on the determined result of the determining unit, whether to retrieve the landmark information again from the first storage unit based on the current position.

3. The landmark search apparatus according to claim 2 , wherein

when the determining unit determines that the retrieved landmark information stored in the second storage unit is invalid, the retrieving unit retrieves again the landmark information from the first storage unit based on the current position, and the second storage unit stores the landmark information retrieved again as new retrieved landmark information, and

when the determining unit determines that the retrieved landmark information stored in the second storage unit is valid, the retrieving unit does not retrieve the landmark information from the first storage unit based on the current position.

4. The landmark search apparatus according to claim 1 , further comprising a display unit configured to display at least a part of the retrieved landmark information,

wherein the display unit controls, based on the determined result of the determining unit, whether to display the at least part of the retrieved landmark information stored in the second storage unit.

5. The landmark search apparatus according to claim 1 , further comprising a recording unit configured to record at least a part of the retrieved landmark information stored in the second storage unit in a predetermined recording medium,

wherein the recording unit controls, based on the determined result of the determining unit, whether to record the at least part of the retrieved landmark information stored in the second storage unit in the recording medium.

6. The landmark search apparatus according to claim 1 , wherein the determining unit determines whether the retrieved landmark information is valid within a predetermined time interval.

7. An electronic apparatus comprising:

the landmark search apparatus according to claim 1 ; and

a display unit configured to display at least a part of the retrieved landmark information.

8. An imaging apparatus comprising:

the landmark search apparatus according to claim 1 ;

an imaging unit configured to capture a subject image formed by an optical system to generate image data; and

a recording unit configured to relate the image data with at least part of the retrieved landmark information and to record them in a recording medium.

9. The imaging apparatus according to claim 8 , wherein the recording unit controls whether to relate the image data with the at least part of the retrieved landmark information and to record them in a recording medium, based on the determined result of the determining unit of the landmark search apparatus.

10. The imaging apparatus according to claim 8 , further comprising an instruction receiving unit configured to receive an instruction for recording the image data generated by the imaging unit in the recording medium,

wherein when the instruction receiving unit receives the instruction for recording the image data generated by the imaging unit in the recording medium, the determining unit determines whether the retrieved landmark information is valid.

11. The imaging apparatus according to claim 8 , wherein the determining unit determines whether the retrieved landmark information is valid within a predetermined time interval.

12. A landmark search method for searching for landmarks around an object, the method comprising:

obtaining a current position of the object;

storing a name of the landmark and position information of the landmark, as landmark information, in a first storage unit, with the name of the landmark related with the position information of the landmark;

retrieving the landmark information from the first storage unit based on the obtained current position;

storing the retrieved landmark information, as retrieved landmark information, in a second storage unit; and

determining whether the retrieved landmark information is valid based on; i) the current position of the object; ii) a previous position of the object at a time of storing the retrieved landmark information in the second storage unit; iii) a first distance between the previous position and a farthest landmark from the previous position in landmarks indicated by the landmark information stored in the second storage unit; and iv) a second distance between the previous position and a landmark which is N-th farthest from the previous position in the landmarks indicated by the landmark information stored in the second storage unit, N being a predetermined number,

wherein the determining determines whether a moving distance of the object from the previous position to the current position is more than a half of the first distance minus the second distance to determine whether the retrieved landmark information is valid.

13. The landmark search method according to claim 12 , wherein the retrieving the landmark information controls, based on a determined result at the determining, whether to retrieve again the landmark information from the first storage unit based on the current position and to store the landmark information retrieved again in the second storage unit.

14. The landmark search method according to claim 12 , further comprising:

displaying at least a part of the retrieved landmark information,

wherein the displaying controls, based on the determined result at the determining, whether to display the at least part of the retrieved landmark information stored in the second storage unit.

15. The landmark search method according to claim 12 , further comprising:

recording at least a part of the retrieved landmark information stored in the second storage unit in a predetermined recording medium,

wherein the recording step controls, based on the determined result of the determining, whether to record the at least part of the retrieved landmark information stored in the second storage unit in the recording medium.

16. The landmark search method according to claim 12 , wherein the determining determines whether the retrieved landmark information is valid within a predetermined time interval.

17. The landmark search apparatus according to claim 1 , wherein N pieces of landmark information which are nearest to the current position and stored in the second storage unit are displayed as a result of retrieving.

18. The landmark search method according to claim 12 , wherein N pieces of landmark information which are nearest to the current position and stored in the second storage unit are displayed as a result of searching.