Method and Device for Traffic Sign Recognition

• US 20100283855A1
• Filed: 07/17/2008
• Published: 11/11/2010
• Est. Priority Date: 07/24/2007
• Status: Active Grant

• Current Assignee: CARIAD SE (Volkswagen AG)
• Original Assignee: Hella KGaA Hueck & Company
• Inventors: Becker, Lars-Peter
• Granted Patent: US 8,643,721 B2
• Time in Patent Office: Days
• US Class Current: 348/148
• CPC Class Codes: G06V 20/582 of traffic signs
• CPC Class Codes: G06V 30/242 Division of the character sequences into groups prior to recognition; Selection of dictionaries

Abstract

In a method and a device for traffic sign recognition, at least one significant feature for a traffic sign is determined which is standardized for a region. The region that corresponds to the determined feature is determined. At least one classification feature and/or at least one classification method is defined depending on the determined region for the recognition of the traffic sign and/or at least one further traffic sign. The recognition of the traffic sign and/or the at least one further traffic sign is performed by using the defined classification feature and/or the defined classification method.

Claims

1. A method for traffic sign recognition, comprising:

on the basis of available image data of at least one reproduction of a traffic sign, performing a first traffic sign recognition with at least one of a first classification feature specified for a first region and a first classification method specified for the first region to determine a first recognition quality of the first traffic sign recognition;

on the basis of the available image data of the at least one reproduction of the traffic sign, performing a second traffic sign recognition with at least one of a second classification feature specified for a second region and a second classification method specified for the second region to determine a second recognition quality of the second traffic sign recognition;

using the at least one of the first classification feature specified for the first region and the first classification method specified for the first region for the traffic sign recognition of the traffic sign when the first recognition quality is greater than the second recognition quality; and

using the at least one of the second classification feature specified for the second region and a second classification method specified for the second region the traffic sign recognition of the traffic sign when the first recognition quality is less than the second recognition quality.

2. The method according to claim 1, characterized in that the second traffic sign recognition is only performed when the recognition quality determined with the aid of the first traffic sign recognition falls below a preset recognition quality limit value.

7. The method according to claim 1, characterized in that, on the basis of available image data of at least one image with a reproduction of at least a part of an area surrounding a vehicle, at least one traffic sign present in this area is determined.

8. The method according to claim 7, characterized in that during a processing of the available image data the traffic sign is detected as an object and is pre-classified as a traffic sign with the aid of a pre-classification method, wherein the object is preferably tracked over several images.

9. The method according to claim 1, characterized in that a region comprises at least one country, a federal state, a canton and another administrative unit having at least one traffic sign specifically specified for the administrative unit.

10. The method according to claim 1, characterized in that each time region-allocated data with the at least one classification feature specified for the respective region or each time region-allocated program data for providing at least one classification method specified for the respective region are held available by a data processing unit for the recognition of the traffic sign, wherein at least two different regions are provided.

11. The method according to claim 10, characterized in that at least one of the region-allocated data and the region-allocated program data are stored in a non-volatile storage area of the data processing unit.

12. The method according to claim 10, characterized in that a region is preset, and in that, on the basis of the preset region, at least one of a classification feature specified for the preset region and a classification method specified for the preset region are used for the recognition of the traffic sign, wherein for each of several possible traffic signs a probability is determined that the possible traffic sign actually is the traffic sign to be classified.

13. The method according to claim 12, characterized in that for each of several images of an image sequence with sequentially recorded images the probabilities for several possible traffic signs is determined.

14. The method according to claim 12, characterized in that the method steps for determining the region are only implemented when the determined probabilities fall below a preset limit value or in periods in which no traffic signs are classified.

15. The method according to claim 1, characterized in that for at least two different regions, data allocated to the respective region are stored, and in that only those data are loaded for classification of the traffic sign which are allocated to the determined region, wherein preferably for each region a data record is stored which is used in the selection or presetting of this region for the classification of traffic signs.

16. The method according to claim 1, characterized in that for each of at least two regions the probability is determined whether, on the basis of the features determined, this region is concerned, wherein preferably the region with the highest determined probability is preset as the current region.

19. The method according to claim 1, characterized in that given the recognition of a traffic sign specified for a region this region is preset for the classification of further traffic signs.

20. The method according to claim 19, characterized in that this traffic sign is an information board at border crossings, wherein the information boards for different regions differ from one another in particular by a country code provided on the information board.

3. A method for traffic sign recognition, comprising:

determining at least one significant feature for a traffic sign, wherein the traffic sign is standardized for a region;

determining the region corresponding to the at least one significant feature;

defining at least one of a classification feature a classification method depending on the determined region for the recognition of the traffic sign; and

performing the recognition of the traffic sign using the at least one of the defined classification feature and the defined classification method.

4. The method according to claim 3, characterized in that at least one of the at least one significant feature is significant for several traffic signs standardized for the region or in that for each of several traffic signs standardized for this region one significant feature is determined, wherein the traffic signs indicate different legal regulations.

5. The method according to claim 4, characterized in that for each of at least two traffic signs at least one feature significant for this traffic sign is determined, wherein the region is determined with the aid of the determined features.

6. The method according to claim 3, characterized in that as a significant feature at least one of a size of the traffic sign, a font type, a symbol characteristic a size of signs that are illustrated on the traffic sign, at least one color, a reflection property and at least one property of support means for supporting the traffic sign is used.

17. The method according to claim 3, characterized in that a traffic sign already classified with a preset first region is classified again with a further preset second region, wherein it is checked whether given the classification with the further preset second region the traffic sign is classified with a higher probability than given the classification with the first preset region.

18. The method according to claim 17, characterized in that this repeated classification of the traffic sign of the preset second region takes place with the same available image data as the classification with the first preset region, wherein the repeated classification of the traffic sign is preferably performed in a period in which no further traffic signs are to be classified, in particular when no traffic signs are detected in the recorded images.

21. The method according to claim 3, characterized in that the region is determined on the basis of several traffic signs having a feature that is specific for a certain region.

22. A device for traffic sign recognition, comprising:

an image recording system for generating image data of at least one image with a reproduction of at least a part of an area surrounding a vehicle; and

a processing unit

that processes the image data and determines a traffic sign that is present in the area covered by the reproduction,

that, on the basis of the image data of the traffic sign, performs a first traffic sign recognition with at least one of a first classification feature specified for a first region and a first classification method specified for the first region, wherein the processing unit determines a first recognition quality of the first traffic sign recognition,

that, on the basis of the image data of the traffic sign, performs a second traffic sign recognition with at least one of a second classification feature specified for a second region and a second classification method specified for the second region, wherein the processing unit determines a second recognition quality of the second traffic sign recognition,

that uses the at least one of the first classification feature specified for the first region and the first classification method specified for the first region for the traffic sign recognition of the traffic sign when the first recognition quality is greater than the second recognition quality, and

that uses the at least one of the second classification feature specified for the second region and the second classification method specified for the second region for the traffic sign recognition of the traffic sign when the first recognition quality is less than the second recognition quality.

23. A device for traffic sign recognition, comprising:

an image recording system for generating image data of at least one image with a reproduction of at least a part of an area surrounding a vehicle; and

a processing unit that processes the image data and determines at least one traffic sign present in the area covered by the reproduction,

wherein the processing unit determines at least one significant feature for the traffic sign, wherein the traffic sign is standardized for a region,

wherein the processing unit determines the region corresponding to the at least one significant feature,

wherein the processing unit defines at least one of a classification feature and a classification method depending on the determined region for the recognition of the traffic sign, and

wherein the processing unit performs the recognition of the traffic sign by using the at least one of the defined classification feature and the defined classification method.