SYSTEM FOR POST PROCESSING GNSS/INS MEASUREMENT DATA AND CAMERA IMAGE DATA

• US 20150120185A1
• Filed: 10/25/2013
• Published: 04/30/2015
• Est. Priority Date: 10/25/2013
• Status: Active Grant

• Current Assignee: Novatel Incorporated (Hexagon AB)
• Original Assignee: Novatel Incorporated (Hexagon AB)
• Inventors: Roesler, Gregory J.
• Granted Patent: US 9,182,236 B2
• Time in Patent Office: Days
• US Class Current: 701/468
• CPC Class Codes: G01C 21/1656 with passive imaging devices, e.g. cameras
• CPC Class Codes: G01S 19/13 Receivers
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/39 the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
• CPC Class Codes: G01S 19/396 Determining accuracy or reliability of position or pseudorange measurements
• CPC Class Codes: G01S 19/40 Correcting position, velocity or attitude
• CPC Class Codes: G01S 19/485 whereby the further system is an optical system or imaging system
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled
• CPC Class Codes: G01S 19/52 Determining velocity

Abstract

A system for performing post processing of GNSS and INS measurement data and image data to provide highly accurate location information for a camera, an INS measurement unit or both performs first processing operations using the GNSS and INS measurement data, to determine position, velocity and attitude solutions. The system then analyzes the solutions to determine which measurement data provide sufficiently reliable solutions from which to determine the precise position, velocity and attitude of the camera, and thus, which measurement data do not provide sufficiently reliable solutions. The system and method then performs more time consuming and processing intensive processing operations using the measurement data and camera image data that are associated with solutions that are not sufficiently reliable.

Claims

1. A post processing navigation mapping system including:

a camera subsystem;

a GNSS/INS subsystem;

one or more processors that receive measurement data and image data from the subsystems, the one or more processors being configured to

calculate sets of position, velocity and attitude solutions and associated variances that correspond in time to images taken by the camera subsystem, by processing the measurement data received from the GNSS/INS subsystem forward in time and backward in time,

determine which of the sets of solutions are reliable and using the reliable sets of solutions to determine position, velocity and attitude information for a camera included in the camera subsystem, and

for sets of solutions determined to be unreliable further process the GNSS/INSS measurement data and the corresponding image data from images that correspond in time to determine further processed solutions and using the further processed solutions to determine position, velocity and attitude information for one or both of the camera and an INS measurement unit included in the GNSS/INS subsystem.

2. The system of claim 1 wherein the one or more processors are further configured to determine a set of solutions is reliable based on a comparison of the forward and backward solutions and associated variances.

3. The system of claim 2 wherein the one or more processors are further configured to determine that the set of solutions is reliable if the forward and backward solutions disagree and only one of the associated variances is below a predetermined threshold.

4. The system of claim 2 wherein the one or more processors are further configured to determine that the set of solutions is unreliable if the forward and backward solutions disagree and the associated variances are below a predetermined threshold.

5. The system of claim 1 wherein the processors are further configured to utilize information derived from the images relating to changes in position, velocity, attitude or any combinations thereof to calculate the further processed solutions.

6. The system of claim 2 wherein the one or more processors are further configured to determine that the set of solutions is unreliable if the forward and backward solutions differ by more than an associated error tolerance and associated variances are both below a predetermined threshold.

7. The system of claim 1 wherein the processors are further configured to utilize a time domain filter to determine the forward and backward solutions.

8. The system of claim 7 wherein the processors are further configured to utilize a filter smoother.

9. The system of claim 1 wherein the one or more processors are further configured to determine locations of selected features in the images.

10. The system of claim 1 wherein the one or more processors are further configured to perform localized bundle or stripwise adjustments using images that are taken during time spans from earlier reliable solutions to later reliable solutions and images corresponding to end points of the time span to determine the further processed solutions.

11. A method for post processing navigation measurement data including:

receiving measurement data from a GNSS/INS subsystem and image data from a camera subsystem,

in one or more processors

calculating sets of position, velocity and attitude solutions and associated variances that correspond in time to images taken by the camera subsystem by processing the measurement data received from the GNSS and INS subsystems forward in time and backward in time,

determining which of the sets of solutions are reliable and using the reliable sets of solutions to determine position, velocity and attitude of a camera included in the camera subsystem, and

for sets of solutions determined to be unreliable further processing the GNSS/INSS measurement data and the image data from images that correspond in time to determine further processed solutions and using the further processed solutions to determine position, velocity and attitude for one or both of the camera and an INS measurement unit included in the GNSS/INS subsystem.

12. The method of claim 11 wherein a given set of solutions is determined to be reliable based on a comparison of the forward and backward solutions and associated variances.

13. The method of claim 12 wherein a given set of solutions is determined to be reliable if the forward and backward solutions disagree and a single associated variance is below a predetermined threshold.

14. The method of claim 12 wherein a given set of solutions is determined to be unreliable if the forward and backward solutions differ and associated variances are below a predetermined threshold.

15. The method of claim 11 wherein information derived from the images relating to changes in position, velocity, attitude or any combinations thereof are utilized to calculate the further processed solutions.

16. The method of claim 12 wherein a given set of solutions is determined to be unreliable if the forward and backward solutions differ by more than an associated error tolerance and associated variances are below a predetermined threshold.

17. The method of claim 11 wherein a time domain filter is utilized to determine the forward and backward solutions and associated variances.

18. The method of claim 17 wherein a filter smoother is further utilized.

19. The method of claim 11 further including determining locations of selected features in the images based on the position and attitude of the camera.

20. The method of claim 11 wherein further processed solutions are determined using localized bundle or stripwise adjustments that use images that are taken during time spans from earlier reliable solutions to later reliable solutions and images corresponding to end points of the time span.