Geometric Calibration of Images Using Homography Extrapolation

The patent performs preliminary geometric calibration of individual cameras using a calibration target before the actual imaging process. This preliminary calibration establishes accurate intrinsic parameters and distortion models for each camera, enabling robust extrinsic parameter estimation even when field of view overlap is minimal. The calibration pattern is captured in advance to create reference data that compensates for limited overlap during operation.

The patent introduces a calibration target with a known geometric pattern as an intermediary object that mediates between multiple cameras. This calibration target serves as a common reference frame that all cameras can observe and relate to, enabling accurate relative pose estimation without requiring direct overlap between camera fields of view. The calibration target acts as an intermediate coordinate system that connects different camera views.

The system performs preliminary calibration of each camera individually using a calibration target before capturing images of the scene. This preliminary action establishes accurate intrinsic parameters and distortion characteristics for each camera. When images with minimal overlap are captured, the pre-calibrated parameters enable accurate extrinsic estimation through the calibration target's known geometry, compensating for the limited overlap.

The patent changes the approach from direct overlap-based extrinsic estimation to a two-stage process: first calibrating intrinsic parameters using a calibration target, then using those calibrated parameters to estimate extrinsic parameters even with minimal overlap. This parameter transformation enables accurate results with fewer cameras by decoupling intrinsic and extrinsic calibration requirements.

The calibration target with known geometric pattern serves as an intermediary reference that all cameras can independently observe and relate to. This intermediary provides a common coordinate system that enables reliable geometric calibration without requiring direct field of view overlap between cameras. Each camera calibrates its position and orientation relative to the calibration target, and the target mediates the relationship between cameras.

The system performs preliminary calibration using the calibration target to establish accurate intrinsic parameters and distortion models before actual imaging. This preliminary action ensures reliable geometric calibration by separating the intrinsic calibration (done with the target) from the extrinsic calibration (done with scene images), allowing minimal or no field of view overlap during operation while maintaining high reliability.