CharuCo Targets

CharuCo Targets

CharuCo targets have uniquely coded fields, which makes it possible to calibrate using a partly occluded or with a non-ideal target location. It also improves robustness against image noise. These properties allow recording information from the very edges of images, which is ideal for accurate and robust determination of lens parameters. Also, the unique coding of feature points allows for stereo calibration in which corners may be partly non-visible.

CharuCo detection is implemented in the OpenCV 3 contrib module and was moved into the main OpenCV objdetect module in recent versions.

Note: OpenCV 4.6 was released with a change to field ordering of ChAruCo boards with even row count. Patterns with an odd number of rows are unaffected by this and compatible with all OpenCV versions.

Our default selection of CharuCo targets use the DICT_5x5 dictionary. If your application requires further customization, please contact us, and we are able to accommodate any customizations of CharuCo boards. You can also provide a PDF drawing of your completely custom pattern.

To mount or position these targets on tripod, frames or fixtures, see Accessories.

Aluminium composite targets

Our larger sized calibration targets are made from aluminium/LDPE composite sheets which offers excellent flatness and stiffness, while being lightweight. Additionally, the composite material offers good thermal stability and corrosion resistance.  

The substrate is carefully machined to size and fitted with 6mm corner radiuses to maximize robustness. The patterns are transferred to the composite material using a specialised precision direct UV (Ultra-Violet) printing process resulting in a durable matte finish. Through extensive testing, we have found this process to be ideal for machine vision applications, where both accuracy, good optical performance and physical robustness are of utmost importance.

For further information, please refer to the aluminium composite datasheet.

Ceramic targets

For ultimate absolute accuracy requirements and smaller FOVs, we offer ceramic targets. These are extremely flat, have close no to thermal expansion, and are manufactured on semi-conductor clean-room lithography lines.

In order to provide good contrast, we use a specially coated blue chrome coating on a white alumina ceramic substrate. On the smallest 75x50mm target, the surface has to be more shiny due to the small feature size. Feature-to-feature dimensional accuracy is better than 10μm.

Please note: we are also able to manufacture ceramic calibration targets with other patterns or designs at dimensions up to 400x400mm. NRE costs apply. Please submit a quote request if interested.

For further information, please refer to the ceramic datasheet.

Precision Manufactured

All of our calibration targets are made from aluminium/LDPE composite which offers excellent flatness and stiffness, while being lightweight. Additionally, the composite material offers good thermal stability and corrosion resistance.  

The patterns are transferred to the composite material using a specialised precision direct UV (Ultra-Violet) printing process resulting in a durable matte finish. Through extensive testing, we have found this process to be ideal for machine vision applications, where both accuracy, good optical performance and physical robustness are of utmost importance.

Sizes

The following sizes are available:

Patterns

We offer two pattern options, Fine and Coarse, which have been specifically designed to work optimally with high (Fine) and low (Coarse) resolution cameras. The following tables illustrate the available options:

Fine (Aluminium composite)

Fine (Ceramic)

Coarse (Aluminium composite)

Aluminium Composite Technical Specifications

Ceramics Technical Specifications

Product Datasheets