Geoaccurate three-dimensional reconstruction via image-based geometry

1. A method of generating a three-dimensional reconstruction of a scene, the method comprising:

generating a high-fidelity point cloud representing a three-dimensional reconstruction of a scene from a plurality of two-dimensional images generated by at least one sensor whose position and orientation are known relative to a fixed coordinate system for each of the two-dimensional images, the high-fidelity point cloud being generated in a relative coordinate system without regard to the position and orientation of the at least one sensor relative to the fixed coordinate system;

generating in the fixed coordinate system a low-fidelity point cloud representing a three-dimensional reconstruction of the scene from the plurality of two-dimensional images using the position and orientation of the at least one sensor relative to the fixed coordinate system such that the high-fidelity point cloud and the low-fidelity point cloud are generated from the same plurality of two-dimensional images, the low-fidelity point cloud having a lower fidelity than the high-fidelity point cloud due to physical sensor model errors in the position and orientation of the at least one sensor;

determining a transformation between the relative coordinate system and the fixed coordinate system based on a relationship between points in the high-fidelity point cloud and corresponding points in the low-fidelity point cloud; and

converting the high-fidelity point cloud from the relative coordinate system to the fixed coordinate system by applying the transformation to points in the high-fidelity point cloud, wherein an impact of the physical sensor model errors on the high-fidelity point cloud in the fixed coordinate system is limited to errors introduced in the transformation.

2. The method of claim 1 , wherein the high-fidelity point cloud is generated using structure from motion (SfM) processing.

3. The method of claim 1 , wherein the relative coordinate system is an arbitrary world coordinate system (WCS) and the fixed coordinate system is an earth-based coordinate system, and wherein the low-fidelity point cloud is generated based on a ground-to-image function of the at least one sensor.

4. The method of claim 1 , wherein the transformation is determined using a sparse high-fidelity point cloud containing only a subset of the points in the high-fidelity point cloud.

5. The method of claim 1 , wherein the transformation is applied to the high-fidelity point cloud via a transformation matrix that performs translation, scaling and rotation to each point in the high-fidelity point cloud such that relative distances between the points in the high-fidelity point cloud are maintained in the fixed coordinate system.

6. The method of claim 1 , wherein the high-fidelity point cloud is converted from the relative coordinate system to the fixed coordinate system without use of a digital elevation map (DEM) or ground control points (GCPs).

7. The method of claim 1 , wherein the position and orientation of the at least one sensor are received as metadata associated with each of the plurality of two-dimensional images, the metadata including global positioning system (GPS) data and inertial navigation system (INS) data.

8. An image reconstruction system for generating a three-dimensional reconstruction of a scene, comprising:

an interface configured to receive a plurality of two-dimensional images generated by at least one sensor whose position and orientation are known relative to a fixed coordinate system for each of the two-dimensional images; and

a processor configured to:

generate a high-fidelity point cloud representing a three-dimensional reconstruction of a scene from the plurality of two-dimensional images, the high-fidelity point cloud being generated in a relative coordinate system without regard to the position and orientation of the at least one sensor relative to the fixed coordinate system;

generate in the fixed coordinate system a low-fidelity point cloud representing a three-dimensional reconstruction of the scene from the plurality of two-dimensional images using the position and orientation of the at least one sensor relative to the fixed coordinate system such that the high-fidelity point cloud and the low-fidelity point cloud are generated from the same plurality of two-dimensional images, the low-fidelity point cloud having a lower fidelity than the high-fidelity point cloud due to physical sensor model errors in the position and orientation of the at least one sensor;

determine a transformation between the relative coordinate system and the fixed coordinate system based on a relationship between points in the high-fidelity point cloud and corresponding points in the low-fidelity point cloud; and

convert the high-fidelity point cloud from the relative coordinate system to the fixed coordinate system by applying the transformation to points in the high-fidelity point cloud, wherein an impact of the physical sensor model errors on the high-fidelity point cloud in the fixed coordinate system is limited to errors introduced in the transformation.

9. The system of claim 8 , wherein the processor is further configured to generate the high-fidelity point cloud using structure from motion (SfM) processing.

10. The system of claim 8 , wherein the relative coordinate system is an arbitrary world coordinate system (WCS) and the fixed coordinate system is an earth-based coordinate system, and wherein the processor is further configured to generate the low-fidelity point cloud based on a ground-to-image function of the at least one sensor.

11. The system of claim 8 , wherein the processor is further configured to determine the transformation using a sparse high-fidelity point cloud containing only a subset of the points in the high-fidelity point cloud.

12. The system of claim 8 , wherein processor is further configured to apply the transformation to the high-fidelity point cloud via a transformation matrix that performs translation, scaling and rotation to each point in the high-fidelity point cloud such that relative distances between the points in the high-fidelity point cloud are maintained in the fixed coordinate system.

13. The system of claim 8 , wherein the processor is further configured to convert the high-fidelity point cloud from the relative coordinate system to the fixed coordinate system without use of a digital elevation map (DEM) or ground control points (GCPs).

14. The system of claim 8 , wherein the interface is further configured to receive the position and orientation of the at least one sensor as metadata associated with each of the plurality of two-dimensional images, the metadata including global positioning system (GPS) data and inertial navigation system (INS) data.

15. A non-transitory computer readable medium encoded with software comprising processor-executable instructions that, when executed by one or more processors, cause the one or more processors to perform functions of:

generate a high-fidelity point cloud representing a three-dimensional reconstruction of a scene from a plurality of two-dimensional images generated by at least one sensor whose position and orientation are known relative to a fixed coordinate system for each of the two-dimensional images, the high-fidelity point cloud being generated in a relative coordinate system without regard to the position and orientation of the at least one sensor relative to the fixed coordinate system;

generate in the fixed coordinate system a low-fidelity point cloud representing a three-dimensional reconstruction of the scene from the plurality of two-dimensional images using the position and orientation of the at least one sensor relative to the fixed coordinate system such that the high-fidelity point cloud and the low-fidelity point cloud are generated from the same plurality of two-dimensional images, the low-fidelity point cloud having a lower fidelity than the high-fidelity point cloud due to physical sensor model errors in the position and orientation of the at least one sensor;

determine a transformation between the relative coordinate system and the fixed coordinate system based on a relationship between points in the high-fidelity point cloud and corresponding points in the low-fidelity point cloud; and

convert the high-fidelity point cloud from the relative coordinate system to the fixed coordinate system by applying the transformation to points in the high-fidelity point cloud, wherein an impact of the physical sensor model errors on the high-fidelity point cloud in the fixed coordinate system is limited to errors introduced in the transformation.

16. The non-transitory computer readable medium of claim 15 , wherein the instructions to generate the high-fidelity point cloud comprise instructions that cause the one or processors to generate the high-fidelity point cloud using structure from motion (SfM) processing.

17. The non-transitory computer readable medium of claim 15 , wherein the relative coordinate system is an arbitrary world coordinate system (WCS) and the fixed coordinate system is an earth-based coordinate system, and wherein the instructions to generate the low-fidelity point cloud comprise instructions that cause the one or more processors to generate the low-fidelity point cloud based on a ground-to-image function of the at least one sensor.

18. The non-transitory computer readable medium of claim 15 , wherein the instructions to determine the transformation comprise instructions that cause the one or processors to determine the transformation using a sparse high-fidelity point cloud containing only a subset of the points in the high-fidelity point cloud.

19. The non-transitory computer readable medium of claim 15 , wherein the instructions to convert the high-fidelity point cloud comprise instructions that cause the one or more processors to apply the transformation to the high-fidelity point cloud via a transformation matrix that performs translation, scaling and rotation to each point in the high-fidelity point cloud such that relative distances between the points in the high-fidelity point cloud are maintained in the fixed coordinate system.

20. The non-transitory computer readable medium of claim 15 , wherein the instructions to convert the high-fidelity point cloud comprise instructions that cause the one or more processors to convert the high-fidelity point cloud from the relative coordinate system to the fixed coordinate system without use of a digital elevation map (DEM) or ground control points (GCPs).