WO2010069380A1

WO2010069380A1 - Method and apparatus for updating map data

Info

Publication number: WO2010069380A1
Application number: PCT/EP2008/067855
Authority: WO
Inventors: Marcin Kmiecik; Krzysztov Miksa; Krzysztof Smiechowicz
Original assignee: Tele Atlas B.V.
Priority date: 2008-12-18
Filing date: 2008-12-18
Publication date: 2010-06-24

Abstract

Embodiments of the present invention provide a method of analysing object data obtained from terrestrial-based mobile mapping data, characterised by: comparing an object stored in an updated object database (330) including object data recently obtained from a mobile mapping process against an existing object database (320) to identify if the object does not exist in the existing object database (320) or differs from a corresponding object in the updated object database (330) and, in response, identifying the object accordingly.

Description

Method and Apparatus for Updating Map Data Field of the Invention

The present invention relates to a method and apparatus for updating map data. In particular, although not exclusively, the present invention relates to a method and apparatus for updating map data for use with a navigation apparatus.

Background to the Invention

Navigation devices that include GPS (Global Positioning System) signal reception and processing functionality are well known and are widely employed as in- car or other vehicle navigation systems. In general terms, a modern portable navigation device (PND) comprises a processor, memory (at least one of volatile and non-volatile, and commonly both), and map data stored within said memory. The processor and memory cooperate to provide an execution environment in which a software operating system may be established, and additionally it is commonplace for one or more additional software programs to be provided to enable the functionality of the navigation to be controlled, and to provide various other functions, such as route guidance.

The map data typically comprises one or more digital files which effectively amount to a database of digital map information, or a map database. The map database is generally based upon a graph comprising nodes which represent junctions or intersections linked by segments representing roads or portions of roads. In order to maintain the usefulness of the navigation device, it is necessary to ensure that the map data is kept up-to-date. That is, to ensure that the map data reflects current road layouts and features of those roads, such as speed limits and other restrictions.

In order to assist in addressing this problem, mobile mapping vehicles are used. A mobile mapping vehicle is a terrestrial vehicle, such as a van, which includes various sensors and measurement devices to record mobile mapping data. The mobile mapping data generally comprises source image data obtained by one or more cameras mounted on the vehicle and/or laser scanner data, and position and orientation information of the vehicle. Mobile mapping vehicles are discussed in more detail in WO 2008/054203 by the same inventor, which is herein incorporated by reference in its entirety for all purposes. An aim of such mobile mapping vehicles is to obtain object information from the mobile mapping data, wherein object information relates to objects encountered by the vehicle whilst surveying a geographical location. For example, object information may relate to signs encountered by the mobile mapping vehicle.

However, it is difficult and time consuming to update the map data from the object information. It is particularly difficult to update the map data from the object information due to an understanding of meaning, or context, of objects being required to associate objects with features of map data. That is, translation between object information and the map data is not intuitive. Therefore, a skilled operator is often required to consider the meaning or context of each object present in the object information in order to update the map data.

It is an object of embodiments of the invention to at least mitigate one or more of the problems of the prior art. In particular, it is an aim of embodiments of the present invention to facilitate the updating of map data.

Summary of the Invention

In pursuit of this aim, a presently preferred embodiment of the present invention provides a method of analysing object data obtained from terrestrial-based mobile mapping data, characterised by: comparing an object stored in an updated object database including object data recently obtained from a mobile mapping process against an existing object database to identify if the object does not exist in the existing object database or differs from a corresponding object in the updated object database and, in response, identifying the object accordingly.

Identifying the object may be achieved by marking a record storing the object data or by copying the object data to a further object database.

Using identified object data a process of updating map data may be simplified. The process of updating map data based upon the mobile mapping process is only required to consider object data which has in some way altered, corresponding to either a change or introduction of terrestrial features since production of the existing object database. In some embodiments, a removal of terrestrial features is identified by comparison of object data in the existing object database against the updated object database to determine whether a terrestrial feature corresponding to the object data still exists.

Object data stored in the updated object database and/or existing object database may comprise a link to source data from which the object data was derived. In some embodiments, if a confidence level associated with an object, indicating a confidence of an object detection process having detected an object corresponding to a terrestrial feature from image or measurement data of the mobile mapping process, is relatively low then source data corresponding to the object data in the existing and updated may be compared to determine if the object data should be identified.

According to a further aspect of the present inventions, there is provided an apparatus for analysing object data obtained from terrestrial-based mobile mapping data, comprising an existing object database storing object data; a processor; and an updated object database including recently obtained object data; wherein the processor is arranged to compare an object stored in the updated object database against the existing object database to identify if the object does not exist in, or differs from a corresponding object stored in, the existing object database and, in response, to identify the object accordingly.

According to a still further aspect of the invention, there is provided an object database storing object data obtained from a terrestrial-based mobile mapping process, comprising an object having associated metadata indicating that a terrestrial feature corresponding to the object has been changed or introduced since production of an existing object database.

Brief Description of the Drawings

Various aspects of the teachings of the present invention, and arrangements embodying those teachings, will hereafter be described by way of illustrative example with reference to the accompanying drawings, in which:

Figure 1 shows an example illustration of a terrestrial mapping vehicle and an operating environment thereof;

Figure 2 shows an example process of producing an object database; Figure 3 shows an apparatus according to an embodiment of the present invention;

Figure 4 shows a method according to an embodiment of the present invention; and

Figure 5 shows another method according to an embodiment of the present invention; and

Figure 6 illustrates operation of a system according to an embodiment of the present invention.

Detailed Description of Embodiments of the Invention

Referring to Figure 1 , there is shown an illustration of a mobile mapping process. A terrestrial vehicle, generally in the form of a mobile mapping van, 1 10 comprises sensors and measurement devices to record mobile mapping data. The sensors (not shown) may include a laser scanning device to record laser measurement data. The van 1 10 may further comprise one or more cameras to record source images. Source images may be recorded at unit time intervals, or unit distance intervals along a route followed by the van 1 10. A geo-spatial location of objects is recorded by the van 1 10 having position and orientation measurement equipment on board to measure a location and orientation of the van 1 10. . The position measurement equipment includes a GPS receiver to receive wireless signals, including location data, broadcast from a plurality of satellites 120 (only one of which is shown) and inertial devices which are used to compute corrected GPS signals as well as orientation data. The wireless signals can be received and subsequently processed to determine a current geo-spatial location of the van 1 10 and to geo-code measured data and recorded source images. The measurement, location and orientation data and captured images are stored in a data storage device 130, which may be located internal to the vehicle 1 10, as mapping data.

Methods are known to detect objects present in the mobile mapping data.

For example, analysis may be undertaken of geo-coded images recorded by the one or more cameras, the laser measurement data etc. As a result of the analysis, object data is stored in an object database. The object data may comprise one or more links to the mobile mapping data, or source data, indicating an origin of each object in the mobile mapping data.

The object data includes metadata identifying a category of an object, one or more attributes of the object and a location of the object in a suitable global location specified in a suitable coordinate or reference system, such as longitude and latitude. A link referencing a source of the object data may also be included in the object data. The object data may further include attribute information or metadata which may identify one or more of a time of capture of the object data, a feature or object category type, a source type e.g. laser or image data and a confidence level indicating a level of confidence of the analysis process e.g. a confidence level of an image recognition process. Objects may include vertical road information sources 140 such as traffic signs, road signs, traffic lights, street signs showing a name of a street etc. Objects may also include horizontal road information sources, such as lane markings and other information conveyed on a road surface.

A process of producing an object database is illustrated in Figure 2. In the mapping process 200 mapping data from the storage device 120 of the mapping data vehicle 110 is analysed in a process 210 to identify objects. Data from one or more additional sources 220 may also be analysed and/or combined with the mapping data 120 in process 210. Other sources include, but are not limited to, information provided by a Governmental Mapping Authority or the like, feedback data from users, which is sometimes known as community feedback e.g. information about inaccuracies or changes to a road network provided by users, field survey information produced as a result of a skilled researcher visiting a location and manually generating object data, or GPS probe data which is generated by users of navigation, or other GPS enabled, devices travelling around the road network. Object data from the sources is stored in an object database 250. The object database 250 comprises links 251 , 252 to the source data 120, 220. However, as noted above, it is costly to update a map database 270 using the object database 205 since a context or meaning of objects in the object database must frequently be understood. Therefore, a skilled researcher 260 is often required to review objects in the object database 250 and manually update the map database 270.

For example, considering the NO ENTRY sign 140 shown in Figure 1 . A lower region of the sign 140 indicates that the NO ENTRY rule excludes buses.

Therefore, the researcher 260 must determine that the no entry does not apply to buses and manually update the map to show that a road in the map data may be driven along only by buses and not other vehicles.

Embodiments of the present invention aim to improve a map database updating process by reducing an amount of object data that must be considered by a skilled researcher. In some embodiments, an amount of data to be transferred from a mapping vehicle is reduced. In some embodiments of the invention, objects are identified which have changed since a previous version of the object data was obtained. Identification may be performed by marking an object record in an object database or by copying or moving the object record to a different object database.

Figure 3 schematically illustrates an apparatus according to an embodiment of the present invention.

The apparatus 300 comprises a processor 310 communicatively coupled to a first object database 320, a second object database 330 and a delta object database

340. The processor 310 may be formed by a dedicated processing device or a suitable programmed general purpose programming device such as a computer having appropriate software executing thereon. The object databases 320, 330, 340 may each be formed by one or a plurality of files stored on one or more storage devices, or may be stored on the same storage device.

The first object database 320 is an object database previously used to update map data. The first map database may be an object database comprising a complete as possible record of objects in a geographical region. The first object database 320 may have originated from one or a combination of sources, such as mobile mapping data or data from a mapping authority or users.

The second object database 330 is an object data which is more recent than the first object database 320. The second object database 330 may be based upon object information from a recent survey by a mapping vehicle of a geographical region corresponding to that of the first object database 320. The second object database 330 may alternatively or additionally include other object data from one or more sources, such as data from the mapping authority or users.

The processor 310 is arranged to perform a comparison process between the first and second databases. In one embodiment, the processor 310 is arranged to perform methods as illustrated in Figures 4 and 5. Referring to Figure 4, a first method carried out by the processor 310 comprises a first step 410. In step 415 an object is selected from the second object database 330. A geographic location of the object is determined in step 420 by referring to object data in the database to retrieve the location in a reference coordinate system, such as a longitude and latitude of the object. In step 425, the processor 310 determines whether a geographically-corresponding object exists in the first database 320. The determination is performed by searching the first object database 320 to determine if an object is located at the same geographic location as the object currently selected from the second object database 330. If, in step 430, it is determined that a corresponding object is not found in the first object database 320, then processing moves to step 435. However, if it is determined that a corresponding object does not exist, then the object is marked in the second object database 330 as "new", indicating that the object has been newly introduced since production of the first object database 320. In step 435, it is determined whether the geographically-corresponding objects in the first and second object databases 320, 330 are identical. This is done by comparing the data associated with each object, such as the object category type and other information. For example, object category types may be compared to determine whether the two objects are both "signs" which are speed limit signs and other object information may be compared to determine whether both speed limit signs indicate the same speed limit, although it will be realised that other information may be compared. If the objects match, then processing moves to step 440 where the object in the second object database is marked as correct. However, if the two objects do not match, that is the objects differ in some way, then the object in the second object database is marked as "changed" in step 450. In step 455 objects marked as either "new" or "changed" are copied or moved to the third object database 340. The method ends in step 460. The result of the method 400 shown in Figure 4 is that any new or changed objects since the first object database are stored in the delta object database 340.

The processor also performs the method 500 shown in Figure 5 to identify any objects which have been removed since the first database 320 was created. The method begins in step 510 and in step 515 an object is selected from the first object database 320. In step 520, a geographic location of the object is determined as in step 420 of method 400. In step 525, it is determined whether a geographically- corresponding object exists in the second object database 330, similar to step 425 of method 400 although in reverse. If a corresponding object exists in step 530, then processing of that object is finished in step 545. However, if the object does not exist in the second object database, then the object is marked as "terminated" in step 535. In step 540, the object is stored in the delta object database 340.

In some embodiments of the above-described methods it may not be possible for the processor 310 to always accurately determine whether an object is to be marked as "new", "changed" or "terminated". For example, the source data may be noisy e.g. an image contains errors or the object is at a significant distance from the camera, or the analysis process leading to creation of the second database 320 has stored an object in the second database having a low confidence level indicating that a level of confidence of the analysis process for that object is relatively low. In this case, the processor 310 may mark a record of an object as "possible", indicating that the processor has not been able to positively identify that the object is "new", "changed" or "terminated". For objects marked as "possible" in the second database 320, a reviewer may then make a rapid assessment of that object to determine if it is new, changed or terminated.

As a result of the methods 400, 500 shown in Figures 4 and 5, the delta object database comprises objects which differ from those on which a previous version of map data is based. It will be realised that various changes may be made to the methods shown in Figures 4 and 5. For example, the methods may be performed in either order. Further, method 400 may be performed on the first object database 320 with objects from the second database 330 being stored in the delta object database 340 and objects in step 445 being marked as "terminated". In which case, the method 500 would be performed on the second object database 330 with objects marked as "new" in step 535. Further, whilst described with reference to the delta object database 340, embodiments of the present invention may be envisaged in which marked records are used as the basis for subsequent processing without compiling the delta object database 340.

Following the above process the delta object database 340, or marked records, are used in a process of updating a map database. However, since the delta object database 340 comprises fewer objects than the second object database a speed of this process may be increased. During the process of updating the map database map features corresponding to objects in an object database are updated to include a link to indicate a source of map information i.e. to indicate objects used as a source of information about that map feature. For example, the map database may include one or more links to objects in the delta database 340. In this way, when subsequent updating processes are performed resulting in objects linking to the map database being marked, it is possible to automatically identify map features requiring to be updated based on those objects.

Referring to Figure 6, an embodiment of the invention is shown in which an amount of data transferred from a mobile mapping vehicle is reduced. A mobile mapping vehicle 610 obtains object information, as described above, upon which an object detection process is performed by a processor 615 to store object data in an object database 630 located in the vehicle 610, corresponding to the second object database 330 described with reference to Figure 3. An object database 620, corresponding to database 320 of Figure 3, comprising a previously complete inventory of known objects is located, for example, in a building of a map database provider.

Previously, all data stored in object database 630 would be exported from the mobile mapping vehicle 610 for comparison against the existing object database 620. However, in embodiments of the present invention, in order to reduce an amount of data required to be exported form the mobile mapping vehicle 610, geo-spatial information 625 identifying a geo-spatial location of objects in the existing object database 620 corresponding to an area surveyed by the mobile mapping vehicle 610 is communicated from the existing object database 620 to the mobile mapping vehicle 610 for receipt by a processor 615 inside the vehicle 610. In some embodiments, the geo-spatial information 625 is communicated to the mapping vehicle 610 wirelessly.

After receiving the geo-spatial information, the processor 615 inside the vehicle 610 extracts image data recorded by the mapping vehicle 610 from the object database 630 corresponding to each location identified by the received geo-spatial information. The image data may then be compressed by the processor 615 for efficient transfer. The processor 615 also performs an object detection process upon the recently obtained object data to detect new objects introduced following the object data in the existing object database having been recorded. The image data and detected objects in the object database 630 not corresponding to geo-spatial locations communicated 635 from the existing object database 620 i.e. new objects are communicated to a second processor 645. In some embodiments, the second processor 645 is located within the building of the map database provider and the image and object data is communicated wirelessly.

The second processor 645 has access to the existing object database 620 and a delta database 640 into which object data corresponding to new, terminated or changed objects will be stored for updating map database. The second processor 645 is arranged to compare the received image and object data 635 against the existing object database 620 and store object data identifying new, changed or terminated objects in the delta object database 640, as previously described with reference to Figures 4 and 5, such that the delta object database can be subsequently used to update the map database. Advantageously, this process reduces an amount of data which must be transferred from the mobile mapping vehicle 610 and reduces a number of objects to be considered to update the map database.

It will be appreciated that embodiments of the present invention can be realised in the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the present invention. Accordingly, embodiments provide a program comprising code for implementing a system or method as claimed in any preceding claim and a machine readable storage storing such a program. Still further, embodiments of the present invention may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.

Claims

1 . A method of analysing object data obtained from terrestrial-based mobile mapping data, characterised by:

comparing an object stored in an updated object database (330) including object data recently obtained from a mobile mapping process against an existing object database (320) to identify if the object does not exist in the existing object database (320) or differs from a corresponding object in the updated object database (330) and, in response, identifying the object accordingly.

2. The method of claim 1 , comprising

selecting the object from the updated object database (330);

determining if a corresponding object exists in the existing object database (32) and, if not, identifying the object accordingly;

if the corresponding object exists in the existing object database (320), determining if the corresponding object has identical object features and, if not, identifying the object accordingly.

3. The method of claim 1 or 2, comprising:

comparing an object in the existing object database (320) against the updated object database (330) to identify if the object does not exist in the updated object database (330) and, if not, identifying the object accordingly.

4. The method of claim 1 , 2 or 3, wherein each identified object is stored in a delta object database (340) storing objects for use in updating a map database (270).

5. The method of any preceding claim, wherein the corresponding object has an identical geographical location.

6. The method of any preceding claim, comprising comparing identified objects against a corresponding portion of map data stored in a map database and determining if the map data is required to be updated.

7. The method of any preceding claim, wherein the objected is identified as new if it does not exist in the first object database, or as changed if the corresponding object does not have identical object features.

8. The method of claim 7, wherein the object is identified as changed if attributes associated with the object differ.

9. The method of any preceding claim, wherein objects correspond to terrestrial features.

10. An apparatus for analysing object data obtained from terrestrial-based mobile mapping data, comprising: an existing object database (320) storing object data; and a processor (310); characterised by: an updated object database (330) including recently obtained object data; wherein the processor (310) is arranged to compare an object stored in the updated object database (330) against the existing object database (320) to identify if the object does not exist in, or differs from a corresponding object stored in, the existing object database (320) and, in response, to identify the object accordingly.

1 1 . The apparatus of claim 10, wherein the processor (310) is arranged to select the object from the updated object database (330), to determine if a corresponding object exists in the existing object database (320) and, if not, to identify the object accordingly; wherein if the corresponding object exists in the existing object database (320), the processor (310) is arranged to determine if the corresponding object has identical object features and, if not, to identify the object accordingly.

12. The apparatus of claim 10 or 1 1 , comprising a delta object database (340), wherein the processor (310) is arranged to store an identified object in the delta object database (340).

13. The apparatus of claim 10, 1 1 or 12, wherein the objected is identified as new if it does not exist in the existing object database (320), or as changed if the corresponding object does not have identical object features.

14. The apparatus of any of claims 10 to 13, wherein the processor (310) is arranged to compare the object stored in the updated object database (330) against a corresponding object located at an identical geographical location stored in the existing object database (320).

15. The apparatus of claim 10 or 1 1 , wherein the processor (310) is arranged to determine a geographical location of an object in the existing object database (320), to communicate the geographical location to a mobile mapping vehicle (610) and to receive object data corresponding to the geographical location from the mobile mapping vehicle (610).

16. An object database (330, 340) storing object data obtained from a terrestrial- based mobile mapping process, comprising an object having associated metadata indicating that a terrestrial feature corresponding to the object has been changed or introduced since production of an existing object database (320).