Circle Target Asymmetric
74,00 €*
Product information "Circle Target Asymmetric"
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Circle Target Asymmetric - Unambiguous Pose Calibration Patterns
Circle grid patterns offer an alternative to checkerboards for camera calibration: instead of detecting corner intersections, the detector locates the centroids of circular blobs, which can be found with high sub-pixel accuracy, especially under blur or soft focus. OpenCV provides dedicated support for circle grids via the findCirclesGrid function, with a selectable flag for either a symmetric or an asymmetric grid layout.
A symmetric grid is prone to a 180° rotational ambiguity, since the pattern looks identical if the board is rotated by half a turn, the detector cannot always resolve a unique orientation from the points alone. An asymmetric grid solves this: by offsetting alternating rows, the pattern becomes non-symmetric under rotation, allowing a unique and unambiguous pose to be determined directly from the detected circle centers. This makes the asymmetric layout the preferred choice (CALIB_CB_ASYMMETRIC_GRID in OpenCV) whenever reliable orientation detection matters, such as robot and camera pose estimation.
Both the generic findCirclesGrid detector and the full calibration pipeline (calibrateCamera) in OpenCV support asymmetric circle grids out of the box, and MATLAB's Computer Vision Toolbox and Camera Calibrator app likewise support circle grid patterns for calibration, so our targets integrate directly into existing workflows on either platform.
Choosing the right resolution
We offer each board size in two pattern densities, so the circle size and spacing can be matched to your camera's resolution and working distance:
- Medium Resolution — larger circles, designed for cameras below 2 megapixels
- High Resolution — finer circles, designed for cameras above 2 megapixels, enabling more points to be resolved within the same board area
Built for precision and durability, indoors or out
- Rigid, dimensionally stable panel keeps the pattern flat and accurately positioned
- Low thermal expansion minimizes pattern drift across temperature swings
- Water-resistant for outdoor use from −50°C to +80°C
- Rated for up to 3 years outdoors without significant degradation
Pattern Specifications
Medium Resolution
| Size (W x H x D) [mm] | Rows x Columns | Circle Radius [mm] | Spacing [mm] |
|---|---|---|---|
| 200 x 150 x 4 | 17 x 11 | 2 | 8 |
| 300 x 200 x 4 | 15 x 11 | 3 | 12 |
| 400 x 300 x 6 | 17 x 11 | 4 | 16 |
| 600 x 400 x 6 | 15 x 11 | 6 | 24 |
| 800 x 600 x 6 | 17 x 11 | 8 | 32 |
High Resolution
| Size (W x H x D) [mm] | Rows x Columns | Circle Radius [mm] | Spacing [mm] |
|---|---|---|---|
| 200 x 150 x 4 | 27 x 18 | 1 | 5 |
| 300 x 200 x 4 | 23 x 18 | 1.5 | 7.5 |
| 400 x 300 x 6 | 27 x 18 | 2 | 10 |
| 600 x 400 x 6 | 23 x 18 | 3 | 15 |
| 800 x 600 x 6 | 27 x 18 | 4 | 20 |
Technical Specifications
| Temperature Application Range | -50°C to +80°C |
|---|---|
| Linear Thermal Expansion | 24 μm / (°C · m) |
| Flatness Tolerance | ±200 μm |
| Relative Pattern Tolerance | ±100 μm |
| Absolute Pattern Tolerance | ±0.1% / m |
| Outdoor Lifetime | Up to 3 years |
| Water Resistance | Yes |