Change detection using curve alignment

1. A computer-implemented method comprising:

receiving, by one or more computing devices, data identifying an object detected in a vehicle's environment, the data including location coordinates for the object;

identifying, by the one or more computing devices, a corresponding feature from pre-stored map information based on the location coordinates and a map location of the corresponding feature, wherein the corresponding feature is defined as a curve and associated with a tag identifying a type of the corresponding object;

identifying, by the one or more computing devices, a tolerance constraint based on the tag identifying the type of the corresponding object;

dividing, by the one or more computing devices, the curve into two or more line segments, each line segment of the two or more line segments having a first position;

changing, by the one or more computing devices, the first position of the one of the two or more line segments to determine a second position of the one of the two or more line segments based on the location coordinates and the tolerance constraint, wherein changing the first position includes at least one of shifting or rotating the first position of the one of the two or more line segments;

determining, by the one or more computing devices, a value based on a comparison of the first position to the second position, wherein the value indicates a likelihood that the corresponding feature has changed; and

using, by the one or more processors, the value to maneuver the vehicle in an autonomous driving mode.

2. The method of claim 1 , wherein the corresponding feature is identified based on whether a distance between the location coordinates and the map location satisfies a threshold.

3. The method of claim 1 , wherein the tolerance constraint limits the at least one of the shifting or rotating of the one of the two or more line segments.

4. The method of claim 1 , further comprising:

identifying a second tolerance constraint based on the tag identifying the type of the corresponding object, and

wherein changing the first position is further based on the second constraint, and the second tolerance constraint prohibits at least one of the shifting or rotating of the first position of the one of the two or more line segments.

5. The method of claim 1 , wherein changing the first position includes both shifting and rotating the first position of the one of the two or more line segments.

6. The method of claim 1 , further comprising comparing the value to a threshold values to determine whether the corresponding feature no longer exists.

7. The method of claim 1 , further comprising comparing the value to a threshold values to determine whether the corresponding feature has been shifted.

8. The method of claim 1 , before dividing, determining whether the detected object used to define a driving lane based on the second type of the second corresponding object.

9. A system comprising one or more computing devices, each having one or more processors configured to:

receive data identifying an object detected in a vehicle's environment, the data including location coordinates for the object;

identify a corresponding feature from pre-stored map information based on the location coordinates and a map location of the corresponding feature, wherein the corresponding feature is defined as a curve and associated with a tag identifying a type of the corresponding object;

identify a tolerance constraint based on the tag identifying the type of the corresponding object;

divide the curve into two or more line segments, each line segment of the two or more line segments having a first position;

change the first position of the one of the two or more line segments to determine a second position of the one of the two or more line segments based on the location coordinates and the tolerance constraint, wherein changing the first position includes at least one of shifting or rotating the first position of the one of the two or more line segments; and

determine a value based on a comparison of the first position to the second position, wherein the value indicates a likelihood that the corresponding feature has changed; and

use the value to maneuver the vehicle in an autonomous driving mode.

10. The system of claim 9 , wherein the corresponding feature is identified based on whether a distance between the location coordinates and the map location satisfies a threshold.

11. The system of claim 9 , wherein the tolerance constraint limits the at least one of the shifting or rotating of the one of the two or more line segments.

12. The system of claim 9 , wherein the one or more computing devices are further configured to:

identify second tolerance constraint based on the tag identifying the type of the corresponding object, and

to change the first position further based on the second constraint, and the second tolerance constraint prohibits at least one of the shifting or rotating of the first position of the one of the two or more line segments.

13. The system of claim 9 , wherein the one or more computing devices are further configured to change the first position by both shifting and rotating the first position of the one of the two or more line segments.

14. The system of claim 9 , wherein the one or more computing devices are further configured to compare the value to a threshold values to determine whether the corresponding feature no longer exists.

15. The system of claim 9 , wherein the one or more computing devices are further configured to compare the value to a threshold values to determine whether the corresponding feature has been shifted.

16. The system of claim 9 , wherein the one or more computing devices are further configured to, before dividing, determine whether the detected object used to define a driving lane based on the second type of the second corresponding object.

17. A non-transitory, tangible computer readable medium on which instructions are stored, the instructions, when executed by one or more processors cause the one or more processors to perform a method, the method comprising:

receiving data identifying an object detected in a vehicle's environment, the data including location coordinates for the object;

identifying a corresponding feature from pre-stored map information based on the location coordinates and a map location of the corresponding feature, wherein the corresponding feature is defined as a curve and associated with a tag identifying a type of the corresponding object;

identifying a tolerance constraint based on the tag identifying the type of the corresponding object;

dividing the curve into two or more line segments, each line segment of the two or more line segments having a first position;

changing the first position of the one of the two or more line segments to determine a second position of the one of the two or more line segments based on the location coordinates and the tolerance constraint, wherein changing the first position includes at least one of shifting or rotating the first position of the one of the two or more line segments;

determining a value based on a comparison of the first position to the second position, wherein the value indicates a likelihood that the corresponding feature has changed; and

using the value to maneuver the vehicle in an autonomous driving mode.

18. The system of claim 9 , further comprising the vehicle.

19. The medium of claim 17 , wherein the tolerance constraint limits the at least one of the shifting or rotating of the one of the two or more line segments.

20. The medium of claim 7 , wherein the one or more processors are further configured to change the first position by both shifting and rotating the first position of the one of the two or more line segments.