Low Gloss Mode

Low Gloss Mode is used to evaluate surfaces where texture and roughness dominate the visual impression, such as pre‑treated metals, primers, electro‑coats, matt and semi‑gloss finishes, and many raw or semi‑finished materials. In these situations, the final appearance of any high‑gloss topcoat depends strongly on the underlying roughness and waviness, so measuring earlier process steps provides valuable insight and control.

In this mode, TAMS generates a full‑field 3D altitude map of the surface and derives roughness‑ and texture‑based parameters from this map.

Quality Control roughness and texture parameters

Low Gloss Mode reports several key indices from the altitude map, without applying additional filtering in the standard algorithm.

• Optical‑Ra (O‑Ra) is an image‑based equivalent of the familiar Ra parameter, calculated as the arithmetical mean deviation of the altitude profile across the measured area. It is derived from the 3D map, so it captures roughness over a defined field rather than a single line.
• Optical‑Rq (O‑Rq) is the root‑mean‑square deviation of the altitude profile, analogous to Rq in classical roughness analysis. Like O‑Ra, it is computed from the full‑field elevation data to give a robust description of surface height variation.
• Waviness describes the larger‑scale movement of the surface texture using slope information and standard deviation calculations. Values run from 0 (very low texture) to around 30 (very strong texture), and are often influenced by upstream processes such as rolling, forming or blasting.
• Quality (Q) in this mode is derived from waviness and expressed on a 0–100 scale, providing a single indicator of how smooth or textured the surface is from a process standpoint.

These parameters allow users to quantify how well different stages (for example substrate, pre‑treatment, low gloss coatings) prepare a surface for later finishing, and to understand which processes have the greatest impact on final appearance.

Advanced roughness analysis

For applications that require more classical ISO‑style roughness evaluation, Low Gloss Mode can be extended with the O‑Rough algorithm. In this configuration, TAMS applies ISO‑16610 band filtering to the altitude map before calculating roughness characteristics.

Users can define high‑pass, low‑pass or band‑pass filters, including multiple bands, to isolate specific wavelength ranges of interest. After filtering, TAMS calculates parameters such as Sa, RaX, RaY and RsM according to ISO 25178, using the full measurement field. This provides a direct bridge between TAMS measurements and traditional profilometers or areal topography systems, making it easier to compare results, set shared limits and integrate low gloss surface control into existing ISO GPS‑based specifications.