	US 12,293,547 B2
	Calibration of cameras and scanners on UAV and mobile platforms
Ayman F. Habib, West Lafayette, IN (US)
Assigned to Purdue Research Foundation, West Lafayette, IN (US)
Filed by Purdue Research Foundation, West Lafayette, IN (US)
Filed on Mar. 20, 2023, as Appl. No. 18/186,376.
Application 18/186,376 is a continuation of application No. 16/792,729, filed on Feb. 17, 2020, granted, now 11,610,337, issued on Mar. 21, 2023.
Claims priority of provisional application 62/806,853, filed on Feb. 17, 2019.
Prior Publication US 2023/0298209 A1, Sep. 21, 2023
Int. Cl. G06T 7/80 (2017.01); B64U 10/13 (2023.01); B64U 20/80 (2023.01); B64U 101/30 (2023.01); G01S 17/89 (2020.01); G06T 7/73 (2017.01); G08G 5/30 (2025.01)

CPC G06T 7/80 (2017.01) [B64U 10/13 (2023.01); B64U 20/80 (2023.01); G01S 17/89 (2013.01); G06T 7/74 (2017.01); G08G 5/30 (2025.01); B64U 2101/30 (2023.01); G06T 2207/10028 (2013.01)]

5 Claims

1. A method for calibrating the boresight mounting parameters for an imaging device mounted to a vehicle, the vehicle having a navigation device for determining the position and orientation of the vehicle relative to a mapping frame coordinate system in a region being imaged by the imaging device, the navigation device defining a body frame coordinate system and the imaging device defining an imaging frame coordinate system offset from said body frame coordinate system by said mounting parameters, the mounting parameters defining the position and orientation of the imaging device relative to the navigation device and including boresight pitch, roll and heading angles relative to the body frame coordinate system, in which the mounting parameters include pre-determined assumed boresight angles, the imaging device operable to image a swath of the region as the vehicle travels over the region, the method comprising:

directing the vehicle in a travel path for calibrating the imaging device, the travel path including three travel lines, two of the travel lines being in parallel and in opposite directions and having a substantially complete overlap of the swath along the two travel lines, and the third travel line being parallel to the other two travel lines with the swath of the third travel line overlapping about 50% of the swath of the other two travel lines;

obtaining image and associated location data along each of the three travel lines;

identifying a tie point I in the image data that is located substantially along the centerline of the swath of the third travel path;

for each of the three travel lines, a, b and c, calculating an estimated position r_I^m(a), r_I^m(b) and r_I^m(c), respectively, of the tie point in the mapping frame coordinate system;

establishing one of the three travel lines, a, as a reference and calculating;

a difference r_I^m(a)−r_I^m(b) between the estimated position r_I^m(a) of the reference travel line a, and the estimated position r_I^m(b) of the travel lines b; and

a difference r_I^m(a)−r_I^m(c) between the estimated position r_I^m(a) of the reference travel line a, and the estimated position r_I^m(c) of the travel lines c; and

calculating biases in the boresight angles, δΔω, δΔφ and δΔκ, based on the differences r_I^m(a)−r_I^m(b) and r_I^m(a)−r_I^m(c), the altitude of the vehicle above the tie point, the lateral distance perpendicular to the travel line a between the tie point and the reference travel line a, the lateral distance perpendicular to the travel line b between the tie point and the travel line b, and the lateral distance perpendicular to the travel line c between the tie point and the reference travel line c; and

adjusting the predetermined assumed boresight angles by the calculated biases in boresight angles.