Methods and systems using digital map data
The present disclosure generally relates to a methods and systems for compensating for changes in the absolute position of locations with respect to the Earth's surface which occur over time due to crustal dynamics. The invention is particularly, although not exclusively, concerned with such compensation in the context of methods using digital map data, for example, methods of localization of a vehicle.
1. A method for compiling a digital map, comprising:
acquiring sensor data indicative of a respective position of at least one object with respect to the Earth's surface at a first time; and
compiling the digital map at a second time different than the first time, the compiling comprising:
obtaining displacement map data including, for each reference location among one or more reference locations, data indicative of a change in a position of the reference location with respect to Earth's surface over time as a result of crustal dynamics;
adjusting, based on the displacement map data, the respective position of the at least one object to compensate for a change in the respective position of the at least one object with respect to the Earth's surface expected to have occurred between the first time and the second time as a result of the crustal dynamics; and
incorporating information about the at least one object into the digital map based on the respective position of the at least one object.
2. The method of claim 1 , wherein adjusting the respective position of the at least one object based on the displacement map data includes:
identifying, from among a set of map tiles in the digital map, a given map tile in which the respective position is located;
determining displacements for one or more reference locations associated with the given map tile using the displacement map data;
determining an adjustment value based on the displacements for the one or more reference locations associated with the given map tile; and
updating, based on the adjustment value, the respective position of the at least one object.
3. The method of claim 2 , wherein:
the displacement map data includes a plurality of shapes, each shape being defined by a respective plurality of reference locations and each shape being associated with one or more map tiles based on a match between a location associated with the shape and locations of the one or more map tiles;
some or all of the given map tile is associated with a given shape; and
the displacements for the one or more reference locations associated with the given map tile are determined based on the data indicative of the change in the position of the respective plurality of reference locations defining the given shape.
4. The method of claim 3 , wherein some or all shapes among the plurality of shapes are triangles.
5. The method of claim 2 , wherein determining the adjustment value based on the displacements for the one or more reference locations includes:
determining, via an interpolation, a relationship between each of the one or more reference locations and the respective position of the at least one object; and
determining, based on the relationships and the data indicative of the change in the position of each of the one or more reference locations, the adjustment value as a displacement of the respective position of the at least one object.
6. The method of claim 5 , wherein the interpolation is a barycentric interpolation.
7. The method of claim 2 , wherein identifying the given map tile includes:
identifying, using the respective location of the at least one object and information about the location of each map tile among the plurality of map tiles in the digital map, the given map tile from among the plurality of map tiles.
8. The method of claim 1 , wherein the data indicative of the change in the position of each reference location comprises, for at least one pair of times:
a speed of change of the position or a distance of the change in the position; and
a direction of the change of the position.
9. The method of claim 1 , wherein incorporating the information about the at least one object into the digital map includes:
adding, to the digital map, coordinate information identifying the respective position of the at least one object.
10. The method of claim 1 , wherein incorporating the information about the at least one object into the digital map includes:
storing, into one or more data storage media, the digital map including the information about the at least one object.
11. The method of claim 1 , wherein compiling the digital map includes:
storing a plurality of layers in the digital map, each layer including a different part of data associated with the digital map, wherein:
a first layer among the plurality of layers includes object position information; and
a second layer among the plurality of layers includes the displacement map data.
12. The method of claim 1 , wherein the displacement map data and the digital map are configured to be used together to determine locations of objects for navigation operations.
13. A method for updating, at a second time, a digital map that was compiled at a first time different than the second time, the method comprising:
acquiring sensor data indicative of a respective position of at least one object with respect to the Earth's surface at a third time; and
updating the digital map, the updating comprising:
obtaining displacement map data including, for each reference location among one or more reference locations, data indicative of a change in a position of the reference location with respect to Earth's surface over time as a result of crustal dynamics;
adjusting, based on the displacement map data, the respective position of the at least one object to compensate for a change in the respective position of the at least one object with respect to the Earth's surface expected to have occurred between the second time and the third time as a result of the crustal dynamics; and
updating existing information about the at least one object in the digital map based on the respective position of the at least one object.
14. The method of claim 13 , wherein adjusting the respective position of the at least one object based on the displacement map data includes:
identifying, from among a set of map tiles in the digital map, a given map tile in which the respective position is located;
determining, using the displacement map data, displacements for one or more reference locations associated with the given map tile;
determining an adjustment value based on the displacements for the one or more reference locations associated with the given map tile; and
updating, based on the adjustment value, the respective position of the at least one object.
15. The method of claim 14 , wherein:
the displacement map data includes a plurality of shapes, each shape being defined by a respective plurality of reference locations and being associated with one or more map tiles based on a match between a location associated with the shape and locations of the one or more map tiles;
some or all of the given map tile is associated with a given shape; and
the displacements for the one or more reference locations associated with the given map tile are determined based on the data indicative of the change in the position of the respective plurality of reference locations defining the given shape.
16. The method of claim 14 , wherein determining the adjustment value based on the displacements for the one or more reference locations includes:
determining, via interpolation, a relationship between each of the one or more reference locations and the respective position of the at least one object; and
determining, based on the relationships and the data indicative of the change in the position of each of the one or more reference locations, the adjustment value as a displacement of the respective position of the at least one object.
17. The method of claim 14 , wherein identifying the given map tile includes:
identifying, using the respective location of the at least one object and information about the location of each map tile among the plurality of map tiles in the digital map, the given map tile from among the plurality of map tiles.
18. The method of claim 13 , wherein the data indicative of the change in the position of each reference location comprises, for at least one pair of times:
a speed of change of the position or a distance of the change in the position; and
a direction of the change of the position.
19. The method of claim 13 , wherein updating the existing information about the at least one object in the digital map includes:
replacing, in the digital map, coordinate information identifying the respective position of the at least one object.
20. The method of claim 13 , wherein updating the existing information about the at least one object in the digital map includes:
updating, on one or more data storage media, the digital map including the information about the at least one object.
21. The method of claim 13 , wherein the displacement map data and the digital map are configured to be used together to determine locations of objects for navigation operations.
22. A computer—readable storage medium storing instructions that, when executed by one or more processors, cause the one or more processors to perform a method for compiling a digital map, the method comprising:
acquiring sensor data indicative of a respective position of at least one object with respect to the Earth's surface at a first time; and
compiling the digital map at a second time different than the first time, the compiling comprising:
obtaining displacement map data including, for each reference location among one or more reference locations, data indicative of a change in a position of the reference location with respect to Earth's surface over time as a result of crustal dynamics;
adjusting, based on the displacement map data, the respective position of the at least one object to compensate for a change in the respective position of the at least one object with respect to the Earth's surface expected to have occurred between the first time and the second time as a result of the crustal dynamics; and
incorporating information about the at least one object into the digital map based on the respective position of the at least one object.