Circle Target Symmetric
74,00 €*
Product information "Circle Target Symmetric"
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Circle Target Symmetric for Camera Calibration
Circle grid patterns are a well-established 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 and tend to be more robust to blur and soft focus than sharp-edged corners. OpenCV provides dedicated support for this pattern through the findCirclesGrid function.
In a symmetric grid, circles are arranged in a regular rectangular lattice, every row and column evenly spaced, which keeps the pattern geometry simple and makes it straightforward to set up and verify. This regularity is well suited to applications where the camera's viewpoint relative to the board is already constrained or known, for example fixed calibration rigs, since the pattern does not need to resolve ambiguous orientations on its own.
Both OpenCV's findCirclesGrid detector (with the CALIB_CB_SYMMETRIC_GRID flag) and the full calibrateCamera pipeline support symmetric circle grids directly, 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.
Note that a symmetric grid can appear visually identical after a 180° rotation, so the detector alone cannot always resolve a unique board orientation from the points. If your application requires an unambiguous pose, such as robot or camera pose estimation from a single view, our Circle Target Asymmetric offsets alternating rows specifically to eliminate this ambiguity.
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 | 11 x 15 | 2 | 12 |
| 300 x 200 x 4 | 10 x 15 | 3 | 18 |
| 400 x 300 x 6 | 11 x 15 | 4 | 24 |
| 600 x 400 x 6 | 10 x 15 | 5 | 36 |
| 800 x 600 x 6 | 11 x 15 | 6 | 48 |
High Resolution
| Size (W x H x D) [mm] | Rows x Columns | Circle Radius [mm] | Spacing [mm] |
|---|---|---|---|
| 200 x 150 x 4 | 22 x 30 | 1 | 6 |
| 300 x 200 x 4 | 20 x 30 | 1.5 | 9 |
| 400 x 300 x 6 | 22 x 30 | 2 | 12 |
| 600 x 400 x 6 | 20 x 30 | 3 | 18 |
| 800 x 600 x 6 | 22 x 30 | 4 | 24 |
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 |