## 1 Introduction  
Additive manufacturing (AM) has gained more attention due to its ability to manufacture complex geometries. AM can build components with sizes ranging from a few microns to a few meters [1]. The primary reason for this flexibility is that there is no component-specific tooling required for the build process. As a result, AM techniques have substantially reduced the number of steps in the production process and time to market [2]. However, parts manufactured using AM techniques have poor surface quality. Poor surface quality due to various asperities poses many challenges in surface characterization [3]. With the recent developments and capabilities of surface metrology instruments, complex geometries in AM components can be measured [4]. The measurement techniques adopted to characterize complex AM geometries range from conventional contact stylus profilometers to non-contact areal topography measurement systems, such as confocal microscopes [5], chromatic confocal microscopes [6], focus variation microscopes [7], and X-ray computed tomography (X-CT) [8]. The primary issue is that the as-built AM components consist of a wide range of surface asperities. Some of the asperities that give rise to large surface texture values are loosely attached particles [9], partially melted particles, balling melts, semi-welded structures [7], staircase effects, and melts zones [10; 11]. Each asperity varies in its size and shape and thus poses measurement difficulties. Apart from this, challenges arise while adopting standard measurement procedures for roughness measurements (as per ISO 4288-Section 7[12] for profile and ISO 25178-2, 3[13; 14] for areal surface texture, respectively) on AM components. Several standard measurement procedures were applied to as-built metal AM components, and their surface characteristics were evaluated. The difficulties and the suitability of the focus variation technique were highlighted. The ability to separate single powder particles using material ratio and spectral density analysis was also highlighted [15]. The difference in surface texture results due to changes in measurement area is evident in the as-built and post-processed conditions [16]. Due to the miniature designs of AM components (branched fuel nozzles [17], cooling channels [16], rocket injectors [18], overhanging and lattice structures), the evaluation length (l\({}_{\text{n}}\)) for texture characterization is insufficient. Due to this reason, many researchers adopted non-standard cut-off wavelength (\(\lambda_{\text{c}}\)) and evaluation length for measurements. For example, an open porous AM structures' surface roughness was quantified using modified equations of profile surface texture parameters due to an insufficient evaluation length [8]. On analyzing AM surfaces, it was found that an area of 2.5 mm \(\times\) 2.5 mm area was enough to characterize the areal surface texture parameters as compared to the 8 mm \(\times\) 8 mm area proposed by ISO 25178. From the analysis performed, a \(\lambda_{\text{c}}\) of 2.5 mm was sufficient to measure AM surfaces having \(Ra\) values that require a \(\lambda_{\text{c}}\) of 8 mm. However, the implications of using such a non-standard cut-off and the deviations in profile roughness measurements were left unexplored [7]. It was also found that measurements were performed that were non-conforming to ISO 4288 recommendations (specifies \(\lambda_{\text{c}}\) 8 mm and l\({}_{\text{n}}\) 40 mm for roughness 10 \(\upmu\)m \(<Ra\leq\) 80 \(\upmu\)m) by using a \(\lambda_{\text{c}}\) of 2.5 mm and l\({}_{\text{n}}\) of 12.5 mm for \(Ra>\) 10 \(\upmu\)m due to insufficient sample length [19]. A two-axis profilometer was used to scan a rectangular surface area (1 mm \(\times\) 5 mm), non-conforming to ISO 25178, to determine the areal surface texture parameters [6].