Map data generator and method for generating map data

1. A map data generator comprising:

a measurement data database;

a map data database;

a processor to execute a program; and

a memory to store the program which, when executed by the processor, performs processes of,

acquiring, as a measurement data piece, a plurality of image data pieces in two dimensions and a distance data piece, the plurality of image data pieces being continuously imaged, and each having an imaging range partly overlapping an imaging range of at least one of the other image data piece in the plurality of image data pieces, the distance data piece indicating a distance to an object within each of the plurality of image data pieces;

relating the acquired measurement data piece with a time data piece to store the acquired measurement data piece and the time data piece in the measurement data database, the time data piece being used for linking the measurement data piece in chronological order to store the measurement data piece in the measurement data database;

updating a map data piece in three dimensions generated based on a plurality of the measurement data pieces, every time the measurement data piece is acquired;

relating the map data piece that is sequentially updated with the time data piece corresponding to the measurement data piece used when the map data piece is updated, to store the map data piece and the time data piece in the map data database;

receiving an input of a designated time, the designated time indicating a time in the past and corresponding to a map data piece to be further updated; and

checking, as the time data piece, the received designated time against the map data database to identify the map data piece to be further updated and corresponding to the designated time,

wherein the updating process comprises upon receiving the designated time redoing the update of the identified map data piece using a newly acquired measurement data piece that is newly acquired after the designated time is received.

2. The map data generator according to claim 1 , wherein

the checking process comprises upon receiving the designated time, checking, as the time data piece, the designated time against the measurement data database to identify each of the plurality of image data pieces,

the program, when executed by the processor, performs a process of displaying each of the plurality of identified image data pieces or the identified map data piece onto a screen,

the receiving process comprises receiving a request for map data update, which indicates a request to update the map data piece, and

the updating process comprises upon receiving the request for map data update while displaying each of the plurality of image data pieces or the map data piece identified at the designated time, redoing the update of the map data.

3. The map data generator according to claim 2 , wherein the displaying process comprises displaying each of the plurality of acquired image data pieces onto the screen every time the measurement data piece is acquired.

4. The map data generator according to claim 2 , comprising a target-position data database configured to store a target-position data piece and the time data piece that are obtained when the plurality of image data pieces are imaged, the target-position data piece being a piece of positional information about a data entry device, the data entry device being configured to acquire each of the plurality of image data pieces to send each of the plurality of image data pieces to the map data generator,

wherein the checking process comprises checking, as the time data piece, the designated time against the target-position data database to identify the target-position data piece, and

the displaying process comprises displaying the identified target-position data piece onto the screen.

5. The map data generator according to claim 3 , comprising a target-position data database configured to store a target-position data piece and the time data piece that are obtained when the plurality of image data pieces are imaged, the target-position data piece being a piece of positional information about a data entry device, the data entry device being configured to acquire each of the plurality of image data pieces to send each of the plurality of image data pieces to the map data generator,

wherein the checking process comprises checking, as the time data piece, the designated time against the target-position data database to identify the target-position data piece, and

the displaying process comprises displaying the identified target-position data piece onto the screen.

6. The map data generator according to claim 2 , wherein

the checking process comprises

checking, as the time data piece, a drop start time as designated and a drop end time as designated against the map data database to identify the map data piece that has been updated from the drop start time to the drop end time, and

deleting the identified map data piece.

7. The map data generator according to claim 3 , wherein

the checking process comprises

checking, as the time data piece, a drop start time as designated and a drop end time as designated against the map data database to identify the map data piece that has been updated from the drop start time to the drop end time, and

deleting the identified map data piece.

8. The map data generator according to claim 4 , wherein

the checking process comprises

checking, as the time data piece, a drop start time as designated and a drop end time as designated against the map data database to identify the map data piece that has been updated from the drop start time to the drop end time, and

deleting the identified map data piece.

9. The map data generator according to claim 5 , wherein

the checking process comprises

checking, as the time data piece, a drop start time as designated and a drop end time as designated against the map data database to identify the map data piece that has been updated from the drop start time to the drop end time, and

deleting the identified map data piece.

10. The map data generator according to, wherein

the updating process comprises

extracting a plurality of features from each of the acquired measurement data piece and another one of the measurement data pieces that is contiguous to the acquired measurement data piece, and

for the number of matching features being smaller than or equal to a threshold, determining that there is a lost state indicating that the map data piece is not updatable, the number of matching features being the number of features that matches with each other among the plurality of features, and

the displaying process comprises upon the determination of the lost state, displaying the determination of the lost state onto the screen.

11. The map data generator according to claim 3 , wherein

the updating process comprises

extracting a plurality of features from each of the acquired measurement data piece and another one of the measurement data pieces that is contiguous to the acquired measurement data piece, and

for the number of matching features being smaller than or equal to a threshold, determining that here is a lost state indicating that the map data piece is not updatable, the number of matching features being the number of features that matches with each other among the plurality of features, and

the displaying process comprises upon the determination of the lost state, displaying the determination of the lost state onto the screen.

12. The map data generator according to claim 4 , wherein

the updating process comprises

extracting a plurality of features from each of the acquired measurement data piece and another one of the measurement data pieces that is contiguous to the acquired measurement data piece, and

for the number of matching features being smaller than or equal to a threshold, determining that there is a lost state indicating that the map data piece is not updatable, the number of matching features being the number of features that matches with each other among the plurality of features, and

the displaying process comprises upon the determination of the lost state, displaying the determination of the lost state onto the screen.

13. The map data generator according to claim 5 , wherein

the updating process comprises

extracting a plurality of features from each of the acquired measurement data piece and another one of the measurement data pieces that is contiguous to the acquired measurement data piece, and

for the number of matching features being smaller than or equal to a threshold, determining that there is a lost state indicating that the map data piece is not updatable, the number of matching features being the number of features that matches with each other among the plurality of features, and

the display process comprises upon the determination of the lost state, displaying the determination of the lost state onto the screen.

14. The map data generator according to claim 10 , wherein

the updating process comprises upon receiving the designated time, making the determination of the lost state indicating whether the map data piece is not updatable based on the newly acquired measurement data piece, before redoing the update of the map data, and

the displaying process comprises displaying a result of the determination onto the screen.

15. The map data generator according to claim 11 , wherein

the updating process comprises upon receiving the designated time, making the determination of the lost state indicating whether the map data piece is not updatable based on the newly acquired measurement data piece, before redoing the update of the map data, and

the displaying process comprises displaying a result of the determination onto the screen.

16. The map data generator according to claim 12 , wherein

the updating process comprises upon receiving the designated time, making the determination of the lost state indicating whether the map data piece is not updatable based on the newly acquired measurement data piece, before redoing the update of the map data, and

the displaying process comprises displaying a result of the determination onto the screen.

17. The map data generator according to claim 13 , wherein

the updating process comprises upon receiving the designated time, making the determination of the lost state indicating whether the map data piece is not updatable based on the newly acquired measurement data piece, before redoing the update of the map data, and

the displaying process comprises displaying a result of the determination onto the screen.

18. A method for generating a map data piece, comprising the steps of:

acquiring, as a measurement data piece, a plurality of image data pieces in two dimensions and a distance data piece, the plurality of image data pieces being continuously imaged, and each having an imaging range partly overlapping an imaging range of at least one of other image data in the plurality of image data pieces, the distance data piece indicating a distance to an object within each of the plurality of image data pieces;

relating the acquired measurement data piece with a time data piece to store the acquired measurement data piece and the time data piece in a measurement data database, the time data piece being used for linking the measurement data piece in chronological order to store the measurement data piece in a database;

updating a map data piece in three dimensions generated based on a plurality of the measurement data pieces, every time the measurement data piece is acquired;

relating the map data piece that is sequentially updated with the time data piece corresponding to the measurement data piece used when the map data piece is updated, to store the map data piece and the time data piece in a map data database;

receiving an input of a designated time, the designated time indicating a time in the past and corresponding to a map data piece to be further updated;

checking, as the time data piece, the received designated time against the map data database to identify the map data piece to be further updated and corresponding to the designated time; and

upon receiving the designated time, stopping the update of the map data, and redoing the update of the identified map data piece using a newly acquired measurement data piece that is newly acquired after the designated time is received.