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Combination of 3D topography data with 2D reflectivity data
In order to assess the overall appearance of an object , it is necessary to measure surface structure and reflectivity in parallel , as they are mutually interdependent , but are combined for an overall visual assessment . V Because our eyes are only capable to acquire 2D information , the human visual system reconstructs 3D information of objects in our brain using shading and reflections . VI That means , the perceived depth of a structure is dependent on the reflection behaviour on the hills and valleys . Since the spectro2profiler uses the same camera and lens system for the acquisition of 3D topography and 2D reflectivity data , it is possible to combine the data of both measurement principles . Thus , the reflection of hills and valleys can be separated . The difference between reflection of hills and valleys , describes the contrast and perceived depth of a structured surface .
A practical example as found in the automotive industry
Many automotive interior components have a leather-like look and are manufactured by different suppliers with different processes and made of various materials . The appearance of the products surface is analyzed in the different development phases , e . g . at the very beginning by the design department in the grain development to approve suppliers and at the very end by quality control in production . Leather grain structures can appear different in contrast although Colour and 60 ° gloss are the same ( Figure 6 ).
The new measurement parameter reflectivity contrast is an ideal measure for production QC of injection or slush moulded parts .
Conclusion
spectro2profiler ( figure 8 ) is a game changer and marks a turning point in the analysis of structured surfaces . The combination of Colour , gloss , 3D topography and 2D reflectivity in one easy to use instrument is a milestone in the objective measurement control of textured surfaces . At this moment , the spectro2profiler incorporates three algorithms for surface structure analysis - leather-like structures , coarse paint textures and fine paint or plastic textures . Due to its excellent technical performance in regards to repeatability and inter-instrument agreement , digital standards can be used as a reference , allowing a flawless communication within a global supply chain .
From now on , our visual perception of colour , gloss and structure can be evaluated in a holistic and objective approach , Colour and appearance harmony when combining different components can be optimized and all this is possible in the laboratory as well as on the production line with the portable spectro2profiler .
Figure 8 : spectro2profiler from BYK-Gardner
Figure 6 : Four dashboard slush skins of same material with different levels of contrast
This can be caused due to different reflectivity levels of the surface on hills and valleys . Up till now this had to be evaluated visually which is subjective and non-repeatable . The results in Figure 7 show how the reflectivity contrast Rc distinguished the samples despite having the same Colour and 60 ° Gloss . Moreover , the results of the reflectivity for hills and valleys provide details about what causes the different reflectivity contrasts .
Contact us for more information – www . byk . com / instruments or FREEphone 0800 4178 298
References
I Woodham , R . J . 1980 . Photometric method for determining surface orientation from multiple images . Optical Engineerings 19 , I , 139-144
II by Meekohi - Own work , CC BY-SA 4.0 , https :// commons . wikimedia . org / w / index . php ? curid = 44925507
III Serge Beucher and Christian Lantuéj workshop on image processing , real-time edge and motion detection ( 1979 ). http :// cmm . ensmp . fr /~ beucher / publi / watershed . pdf
IV Hunter , R . S . ( 1937 ). Methods of determining gloss . Journal of Research of the National Bureau of Standards , 18 ( 1 ), 19 – 41 .
Figure 7 : Reflectivity and gloss results of four leather grains of same grain type
V Qi , L ., Chantler , M . J ., Siebert , J . P ., & Dong , J . ( 2012 ). How mesoscale and microscale roughness affect perceived gloss . Edinburgh , Scotland : Lulu Press , Inc .
V1 A . Nischwitz et al ., Computergrafik und Bildverarbeitung , Vieweg + Teubner Verlag | Springer Fachmedien Wiesbaden GmbH 2011
6 DECEMBER 2020 twitter : @ surfaceworldmag