Method and system for map matching of road sign observations

1. A method comprising:

receiving, by one or more sensors associated with a vehicle, a road sign observation information;

identifying a plurality of candidate links based on a first distance between a location of the road sign observation information detection and a plurality of shape points;

calculating, by a processor, a heading difference between each of the plurality of candidate links and the location of the road sign observation information detection;

filtering one or more qualified links from the plurality of candidate links based on determining that the heading difference is within a predetermined heading difference threshold;

matching the road sign observation information to at least one of the one or more qualified links based on a second distance; and

initiating an update of a map database with the at least one or more matched qualified links.

2. The method of claim 1 , wherein matching the road sign observation information further comprises:

calculating, by the processor, a plurality of point-to-line distances between each of the one or more qualified links and the location of the road sign observation information detection;

selecting a smallest value of a point-to-line distance from the plurality of point-to-line distances as the second distance; and

matching the road sign observation information to the at least one of the one or more qualified links based on the second distance.

3. The method of claim 2 , further comprising:

adjusting the matched one or more qualified links to identify at least one of an upstream link and a downstream link as a matched link for the road sign observation information based on an adjustment criteria.

4. The method of claim 3 , wherein the adjustment criteria comprises:

checking a length of the one or more qualified links selected for matching the at least one of the upstream link and the downstream link with the road sign observation information; and

selecting the downstream link as the matched link for the road sign observation information if the length of the one or more qualified links is lesser than a predetermined length threshold and the location of the road sign observation information detection is within 50th percentile to 100th percentile of the one or more qualified links.

5. The method of claim 3 , wherein the adjustment criteria comprises:

checking a length of the one or more qualified links selected for matching the at least one of the upstream link and the downstream link with the road sign observation information; and

selecting the downstream link as the matched link for the road sign observation information if the length of the one or more qualified links is greater than a predetermined length threshold and the location of the road sign observation information detection is within 75th percentile to 100th percentile of the one or more qualified links.

6. The method of claim 1 , wherein the first distance is in a range of 60 meters to 300 meters.

7. The method of claim 1 , wherein the heading difference threshold is in a range of 10 degrees to 50 degrees.

8. An apparatus comprising:

at least one processor; and

at least one memory including computer program code for one or more programs, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following:

receive, by one or more sensors associated with a vehicle, a road sign observation information;

identify a plurality of candidate links based on a first distance between a location of the road sign observation information detection and a plurality of shape points;

calculate a heading difference between each of the plurality of candidate links and the location of the road sign observation information detection;

filter one or more qualified links from the plurality of candidate links based on determining that the heading difference is within a predetermined heading difference threshold;

match the road sign observation information to at least one of the one or more qualified links based on a second distance; and

initiate an update of a map database with the at least one or more matched qualified links.

9. The apparatus of claim 8 , wherein the apparatus is further caused to:

calculate a plurality of point-to-line distances between each of the one or more qualified links and the location of the road sign observation information detection;

select a smallest value of a point-to-line distance from the plurality of point-to-line distances as the second distance; and

match the road sign observation information to the at least one of the one or more qualified links based on the second distance.

10. The apparatus of claim 9 , wherein the apparatus is further caused to:

adjust the matched one or more qualified links to identify at least one of an upstream link and a downstream link as a matched link for the road sign observation information based on an adjustment criteria.

11. The apparatus of claim 10 , wherein the adjustment criteria comprises:

checking a length of the one or more qualified links selected for matching the at least one of the upstream link and the downstream link with the road sign observation information; and

selecting the downstream link as the matched link for the road sign observation information if the length of the one or more qualified links is lesser than a predetermined length threshold and the location of the road sign observation information detection is within 50th percentile to 100th percentile of the one or more qualified links.

12. The apparatus of claim 10 , wherein the adjustment criteria comprises:

checking a length of the one or more qualified links selected for matching the at least one of the upstream link and the downstream link with the road sign observation information; and

selecting the downstream link as the matched link for the road sign observation information if the length of the one or more qualified links is greater than a predetermined length threshold and the location of the road sign observation information detection is within 75th percentile to 100th percentile of the one or more qualified links.

13. The apparatus of claim 8 , wherein the first distance is in a range of 60 meters to 300 meters.

14. The apparatus of claim 8 , wherein the heading difference threshold is in a range of 10 degrees to 50 degrees.

15. A computer program product comprising at least one non-transitory computer-readable storage medium having computer-executable program code instructions stored therein, the computer-executable program code instructions comprising program code instructions for:

receiving, by one or more sensors associated with a vehicle, a road sign observation information;

identifying a plurality of candidate links based on a first distance between a location of the road sign observation information detection and a plurality of shape points;

calculating a heading difference between each of the plurality of candidate links and the location of the road sign observation information detection;

filtering one or more qualified links from the plurality of candidate links based on determining that the heading difference is within a predetermined heading difference threshold;

matching the road sign observation information to at least one of the one or more qualified links based on a second distance; and

initiating an update of a map database with the at least one or more matched qualified links.

16. The computer program product of claim 15 , wherein matching the road sign observation information further comprises:

calculating a plurality of point-to-line distances between each of the one or more qualified links and the location of the road sign observation information detection;

selecting a smallest value of a point-to-line distance from the plurality of point-to-line distances as the second distance; and

matching the road sign observation information to the at least one of the one or more qualified links based on the second distance.

17. The computer program product of claim 16 further comprising program code instructions for:

adjusting the matched one or more qualified links to identify at least one of an upstream link and a downstream link as a matched link for the road sign observation information based on an adjustment criteria.

18. The computer program product of claim 17 , wherein the adjustment criteria comprises:

checking a length of the one or more qualified links selected for matching the at least one of the upstream link and the downstream link with the road sign observation information; and

selecting the downstream link as the matched link for the road sign observation information if the length of the one or more qualified links is lesser than a predetermined length threshold and the location of the road sign observation information detection is within 50th percentile to 100th percentile of the one or more qualified links.

19. The computer program product of claim 17 , wherein the adjustment criteria comprises:

checking a length of the one or more qualified links selected for matching the at least one of the upstream link and the downstream link with the road sign observation information; and

selecting the downstream link as the matched link for the road sign observation information if the length of the one or more qualified links is greater than a predetermined length threshold and the location of the road sign observation information detection is within 75th percentile to 100th percentile of the one or more qualified links.

20. The computer program product of claim 15 , wherein the first distance is in a range of 60 meters to 300 meters and the heading difference threshold is in a range of 10 degrees to 50 degrees.