Machine vision methods using feedback to determine calibration locations of multiple cameras that image a common object
US5978521A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 25, 1997 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Sep 25, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2210/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The invention provides improved machine vision methods for determining a calibration relationship among the imaging reference frames of multiple cameras (or other image acquisition devices) that acquire images of a common moveable object. The calibration relationship includes parameters for transforming positional coordinates among the camera's respective imaging reference frames. The method includes placing on the common object, stage, or belt a plurality of fiducials, e.g., calibration marks, that are at known positions relative to each other with respect to a frame of reference referred to as the "alignment reference frame"; aligning an axis of the alignment reference frame with an axis of the object's reference frame of motion, i.e., the reference frame in which the object, frame or belt moves; placing a respective fiducial in the field of view of each camera; determining a calibration relationship among the imaging reference frames of the respective image acquisition devices as a function of (i) the known relative locations of the fiducials (vis-a-vis the alignment reference frame), (ii) the fiducial calibrating positions determined for each camera (vis-a-vis that camera's acq…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.