What PTB Certification Means for Industrial 3D Measurement Accuracy

Accuracy and reliability are key factors when advanced manufacturers choose an industrial metrology solution. In quality control, a few microns can determine whether a part passes or fails. In safety-critical applications, small errors can have a much greater impact.

With more than 20 years of experience in high-precision 3D vision, SHINING 3D serves customers in more than 100 countries and regions. Its global reputation is built not only on product performance, but also on rigorous international certifications.

Among them, the dual precision certification from the Physikalisch-Technische Bundesanstalt (PTB) is an important part of SHINING 3D’s precision system.

This article explains what PTB certification means and how SHINING 3D combines certified algorithms, independent technology, and integrated hardware and software to ensure accurate, reliable, and traceable industrial measurement.

PTB Certification: A Benchmark for Measurement Algorithms

For industrial inspection software, algorithms directly affect measurement results. That is why certification from an independent authority is more than a credential. It provides an objective check of a software’s accuracy, reliability, and traceability.

Founded in 1887, the Physikalisch-Technische Bundesanstalt (PTB) is Germany’s national metrology institute and a leading organization in precision measurement and metrology. PTB is known for its rigorous certification process. It also compares its measurement standards with those of other countries to maintain high levels of accuracy and consistency.

Physikalisch-Technische Bundesanstalt

For fitting algorithms, PTB uses its TraCIM online certification system to assess methods commonly used in industrial metrology. These include:

• Least-squares (Gaussian) fitting

• Minimum-zone (Chebyshev) fitting

SHINING3D Inspect software with PTB certification

PTB requires software results to stay within very tight limits compared with verified reference values.

Depending on the measurement task, certified accuracy can reach:

• 0.1 μm for position and size

• 0.1 μrad for direction and angle

• 0.1 μm for form error

Reference values of PTB assessment

These strict requirements make PTB certification an important benchmark for industrial measurement software.

PTB certifications are also widely recognized under the CIPM MRA, the international Mutual Recognition Arrangement for national measurement standards and calibration certificates.

This provides internationally recognized metrological support for products serving global markets.

Fitting Algorithms: The Foundation of Measurement Accuracy

In 3D inspection, software uses scanned point-cloud data to create ideal geometric features such as circles, cylinders, and planes. This process is called fitting. Simply put, a fitting algorithm uses a mathematical method to find the best-fit geometric feature from a set of measured points.

In accordance with standards such as ISO 5459, GB/T 1958, and GB/T 47757, fitting algorithms constitute a comprehensive family of methods; the four most widely applied and representative types among them are the "least squares (Gaussian) fitting," "minimum-zone (Chebyshev) fitting," "maximum inscribed fitting," and "minimum circumscribed fitting."

Least-squares fitting minimizes the sum of squared deviations between the measured points and the fitted feature. It focuses on overall deviation and is less sensitive to individual outliers. This makes the results stable and repeatable. It is commonly used for diameter, distance, and angle measurements.

Least-squares fitting

Minimum-zone fitting minimizes the maximum deviation while containing all measured points. It focuses on the worst-case deviation and is more sensitive to issues such as burrs and contamination. This makes it useful for evaluating actual form error and for GD&T assessment.

Minimum-zone fitting

Maximum inscribed fitting finds the largest ideal feature that fits inside the measured feature. For example, it can be used to calculate the largest inscribed circle inside a hole. It is commonly used to evaluate internal features, hole size, and mating conditions.

Maximum inscribed fitting

Minimum circumscribed fitting finds the smallest ideal feature that encloses all measured points. For example, it can be used to calculate the smallest circumscribed cylinder around a shaft. It is commonly used to evaluate external features, shaft size, and mating conditions.

Minimum circumscribed fitting

The right method depends on the feature, applicable standards, and functional requirements of the part.

Independent Technology: SHINING3D Inspect Software

To reduce long-term reliance on imported industrial metrology software, SHINING 3D developed its own 3D inspection software, SHINING3D Inspect.

SHINING 3D developed the software independently, from core algorithms to software architecture. Built around international standards, SHINING3D Inspect supports 3D comparison, 3D measurement, GD&T evaluation, and inspection report generation.