GEOCAL is a geometric camera calibration device that uses a beam expanded laser in combination with a diffractive optical element (DOE). This device introduces a new dimension in geometric camera calibration.
Geometric camera calibration is essential for systems from certain industries, particularly those relying on the detection of objects in a moving scene (e.g., automotive, ADAS, security). After geometric calibration, the camera system will be able to more concretely measure distances and detect objects in a scene. A calibrated system will also be better equipped to compensate for high distortion levels (especially for wide field-of-view cameras) and to accurately align stereo camera pairs.
What are the main characteristics of GEOCAL?
- Ability to generate a regular grid of light spots originating from infinity
- Measure geometric distortion, focal length, and principal point
- The camera position is translation invariant (to a certain extent)
- Easily manage the angle of camera rotation
- No relay lens required
- A very compact design
- Calibrate large field-of-view cameras
- Stereo camera alignments and adjustments
- Remove lens distortion using GEOCAL and OpenCV
Why the GEOCAL?
The methods currently utilized for geometric camera calibration rely on test charts with regular patterns, but these patterns need to be scaled depending on the field of view and the intended object distance. Another problem facing the modern methods is the dependence on a relay lens when using a compact device or wanting to calibrate from infinity. GEOCAL avoids the use of test charts and a relay lens while, at the same time, improving the overall accuracy of the calibration. Finally, GEOCAL is suitable for measuring geometric distortion without the use of a test chart.
| Test feature | Checkerboard | GEOCAL |
|---|---|---|
| A compact solution that saves floor space | ||
| Test multiple FoVs without reconfiguration | ||
| Calibrate multiple cameras at the same time* | ||
| Does not require external lighting | ||
| Does not require large test charts for wide FoVs or long focus distances | ||
| Measures INTRINSIC and EXTRINSIC paramters | ||
| No relay lens required | ||
| Able to align stereo pairs |
*Assuming that the lenses all fit inside the DOE port diameter
GEOCAL XL
In addition to the standard GEOCAL, we also offer the GEOCAL XL. This version has a significantly larger output window with a useable aperture of Ø 155 mm as opposed to the standard Ø 77 mm. The GEOCAL XL is ideal for geometric calibration of cameras with large front lenses and in instances where the distance between the camera and GEOCAL needs to be large (e.g., calibrating through a windshield).
GEOCAL IR
The GEOCAL IR version expands the laser diode wavelength range to 935 nm, allowing you to perform geometric camera calibrations in the NIR (near-infrared region.
GEOCAL evaluation software
The GEOCAL has a standalone software with a GUI interface for evaluating test results. An API is also available for our customers to apply the GEOCAL functionality into to their custom software, production line solutions, or device testing applications. Both the software and API are compatible with the GEOCAL XL. Please contact our sales team for more information on the API.
For further questions please see our FAQ section available for download at the bottom of this page.
A technical background on geometric camera calibration is also available for download at the bottom of this page.
| GEOCAL | |
|---|---|
| Principle | DOE-based geometric calibration of digital cameras |
| Light source | Frequency-stabilized diode laser |
| Wavelength | 632,8 nm |
| Diffractive optical element (DOE) | Generates a very evenly distributed point grid, virtually originating from infinity |
| Output window | Usable aperture: Ø 77 mm (camera lens needs to have an equal or smaller diameter) Usable aperture XL: Ø 155 mm (camera lens needs to have an equal or smaller diameter) |
| Usable FoV | Approx. 30 – 120° (more extreme values still need to be tested) |
| Output power | 5 mW |
| Dimensions (W x H x D) | ca. 550 mm x 144 mm x 162 mm XL ca. 850 mm x 244 mm x 270 mm |
| Weight | Approx. 4.5 kg Approx. 10 kg |
