Automated Camera Calibration (ACAL) is a computer program that automates the generation of calibration data for camera models used in machine vision systems. Machine vision camera models describe the mapping between points in threedimensional (3D) space in front of the camera and the corresponding points in two-dimensional (2D) space in the camera's image. Calibrating a camera model requires a set of calibration data containing known 3D-to-2D point correspondences for the given camera system. Generating calibration data typically involves taking images of a calibration target where the 3D locations of the target's fiducial marks are known, and then measuring the 2D locations of the fiducial marks in the images. ACAL automates the analysis of calibration target images and greatly speeds the overall calibration process. ACAL consists of three modules:
- ACALDOTS — the primary module — takes calibration target images, locates and measures the 2D locations of the target's fiducial marks and then synthesizes their corresponding 3D locations based on knowledge of the calibration target's geometry and its 3D location. ACALDOTS handles uneven lighting, large-scale variations due to range differences, and barrel distortion effects of the type found in wide-angle lenses. It understands both planar and corner-cube (i.e., 3D) calibration target geometries.
- ACALINFO takes the calibration data produced by ACALDOTS and estimates an initial 3D position and orientation (i.e., camera pose) for the camera to seed the estimation of the remaining camera model parameters.
- ACALFIX takes the original calibration data and the camera model produced from it and generates a refined set of calibration data by removing localization errors in the 2D fiducial mark positions introduced by perspective foreshortening caused by the calibration target's orientation and geometry.
The automation in ACAL is robust enough that under even extreme image conditions, the required input from the user averages to no more than about one mouse click per target fixture.
This program was written by Siqi Chen, Yang Cheng, and Reg Willson of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Software category.
This software is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-41312.
This Brief includes a Technical Support Package (TSP).
Automated Camera Calibration
(reference NPO-41312) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) focused on Automated Camera Calibration, referenced as NPO-41312 in NASA Tech Briefs. It outlines advancements in camera calibration technology, emphasizing improvements in data collection, feature location, and calibration accuracy.
Key improvements highlighted include:
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Streamlined Data Collection: The use of tools like GALTCalib and ACALINFO enhances the efficiency of gathering necessary data for calibration processes.
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Automated Feature Location: The implementation of ACALDOTS automates the identification of features within images, which is crucial for accurate calibration.
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Improved Calibration Accuracy: The document details how tools such as ACALDOTS and ACALFIX contribute to enhanced calibration precision. ACALDOTS improves centroiding accuracy through techniques like subpixel edge localization and least squares ellipse fitting. ACALFIX refines 5D data to address perspective and radial distortion, significantly enhancing the accuracy of corner cube calibration.
The document also provides contact information for further assistance, including the NASA STI Help Desk, which can be reached via telephone, fax, or email. It encourages users to comply with U.S. export regulations and notes that the information may contain proprietary content.
Overall, the Technical Support Package serves as a resource for understanding the advancements in automated camera calibration, which have broader applications in various technological, scientific, and commercial fields. It underscores the importance of accurate camera calibration in mapping and imaging technologies, which are vital for aerospace and other industries. The document is a part of NASA's efforts to disseminate knowledge and foster innovation through its Commercial Technology Program, making the results of aerospace-related developments accessible to a wider audience.
In summary, this document encapsulates the significant strides made in automated camera calibration, providing essential tools and methodologies that enhance the accuracy and efficiency of the calibration process, thereby supporting various applications in science and technology.
