EN ISO 25178-71:2017 is the GPS (Geometrical Product Specification) standard that defines software measurement standards for areal surface texture. It specifies two types of software etalons - Type S1 (softgauge) and Type S2 (reference software) - and defines the standardized SDF (surface data file) format used for Type S1 reference data. The standard supports calibration and verification of measurement software and instruments that apply the areal surface texture methods in the ISO 25178 series (chain link G).
Key topics and technical requirements
- Types of software measurement standards
- Type S1 (softgauge): Reference data files intended to reproduce known measurand values for verifying instrument software.
- Type S2: Reference software implementations used as comparison/benchmark tools.
- SDF file format (Type S1)
- Standardized record structure including Record 1 (Header), Record 2 (Data area) and Record 3 (Trailer).
- Header fields defined (examples listed in the standard): version number, instrument manufacturer identifier, creation/modification date/time, number of points per profile (M) and number of profiles/traces (N), X/Y/Z scale factors, Z resolution, compression type, data type and checksum type.
- Data encodings and numeric representations (CHAR, BYTE, UINT16, INT16, INT32) are specified to ensure unambiguous interpretation.
- Verification & uncertainty
- Software measurement standards are intended to reproduce measurand values with known specification uncertainty so they can be used to verify software outputs.
- GPS context
- This part is part of the ISO 25178 areal surface texture chain and aligns with GPS principles and operators.
Applications - who uses this standard
- Metrology laboratories and calibration houses - to calibrate and verify measurement systems (instruments and software) that report areal surface texture parameters.
- Instrument manufacturers - to supply and test instrument software against standardized SDF softgauges.
- Software developers and validation engineers - to implement or test surface texture calculation algorithms and to exchange reference datasets.
- Research and academia - for reproducible experiments and comparison of areal surface measurement methods.
Related standards
Key normative references and related documents include:
- ISO 25178‑1 / -2 / -3 (areal surface texture fundamentals, parameters and operators)
- ISO 5436‑2 (profile method software measurement standards)
- ISO 16610 (filtration)
- ISO 17450‑2, ISO/IEC Guide 98‑1, VIM (Guide 99)
EN ISO 25178-71:2017 enables consistent, interoperable verification of areal surface texture software and supports reliable calibration workflows across industry and research. Keywords: EN ISO 25178-71:2017, ISO 25178-71, softgauge, SDF file format, Type S1, Type S2, areal surface texture, software measurement standards, GPS, calibration.