Ramesh, Girish

Turner, Martin

Wortmann, Franz

English

The University of Manchester - Institutional Repository

The University of Manchester ResearchAnalysis of hair shine using hair rendering and subjectiveevaluationDocument VersionFinal published versionLink to publication record in Manchester Research ExplorerCitation for published version (APA):Ramesh, G., Turner, M., & Wortmann, F. (2016). Analysis of hair shine using hair rendering and subjectiveevaluation. Paper presented at 7th International Conference on Applied Hair Research, Red Bank, United States.Citing this paperPlease note that where the full-text provided on Manchester Research Explorer is the Author Accepted Manuscriptor Proof version this may differ from the final Published version. If citing, it is advised that you check and use thepublisher's definitive version.General rightsCopyright and moral rights for the publications made accessible in the Research Explorer are retained by theauthors and/or other copyright owners and it is a condition of accessing publications that users recognise andabide by the legal requirements associated with these rights.Takedown policyIf you believe that this document breaches copyright please refer to the University of Manchester’s TakedownProcedures [http://man.ac.uk/04Y6Bo] or contact uml.scholarlycommunications@manchester.ac.uk providingrelevant details, so we can investigate your claim.Download date:09. Jun. 2022Analysis of hair shine using hair rendering and subjective evaluationG. Ramesha, M. J. Turnerb, B. Schroederc and F.J. WortmannaaSchool of Materials, University of Manchester, United KingdombSchool of Computer Science, University of Manchester, United KingdomcBASF Personal Care and Nutrition GmbH, Duesseldorf, GermanyHair shine (lustre/gloss) is a very desirable attribute to consumers within the cosmetic industry.It is also an important characteristic within Computer Graphics (CG) based imagery, providingan improved perception of realism.Synthesising realistic CG human hair is a difficult task, primarily because of the number andgeometry of hair fibres, but also because of the duality of hair. Its appearance depends not onlyon each fibre (local properties) but also on the hair considered as a volume (global properties).The local properties of an individual hair fibre define the way that it is illuminated so for exam-ple when the hair is considered as a volume, global properties such as translucency and shadowsbecome especially pertinent to creating a convincing appearance. Hair rendering deals with allof these effects. Over the last 10 years, major progress has been made in the area of physically-based hair rendering, which involves the construction of analytical models to represent the lightscattering within hair fibres. Goniophotometric measurements of fibres have now been used toquantify scattering inside a single fibre (single scattering) and scattering events inside a groupof multiple fibres or a strand (multiple scattering)[1, 2], so we are able to validate and modifythese models.Using these single and multiple scattering models, a framework was developed to analyse hairshine using CG images and subjective evaluation. In an initial study, CG images of hair wereconstructed with different lighting conditions, hair geometry, colour, scattering effects and var-ious other factors. These images were then presented to a panel in order to evaluate themsubjectively on the basis of realism to create an index of realism for each of the scattering mod-els based on the various environmental factors[3, 4].This study also explored a novel method to represent random orientation or arrangement offibres within a hair strand. The randomness, termed “entropy”, helps to determine the overalleffect caused by minor changes of orientation on hair shine by simulating their effect using com-puter graphics techniques. This helps to understand the effect even at small entropy values ofdisoriented hair on the stability of subjective hair shine testing and its robustness to change.References[1] S. R. Marschner, H. W. Jensen, M. Cammarano, S. Worley, and P. Hanrahan, “Light scattering from humanhair fibers,” in ACM Transactions on Graphics (TOG), vol. 22, pp. 780–791, ACM, 2003.[2] F. Wortmann, z. W. E. Schulze, and A. Bierbaum, “Analyzing the laser-light reflection from human hair fibers.i. light components underlying the goniophotometric curves and fiber cuticle angles.,” Journal of cosmeticscience, vol. 54, no. 3, pp. 301–316, 2002.[3] F. Wortmann, G. Wortmann, A. S. z. Wiesche, and H. M. Haake, “Considerations of a consistent model forthe reflection of light from human hair,” in HairS’13, 18th International Hair-Science Symposium, 2013.[4] G. Ramesh and M. J. Turner, “Measuring Realism in Hair Rendering,” in Theory and Practice of ComputerGraphics (S. Czanner and W. Tang, eds.), The Eurographics Association, 2013.

Analysis of hair shine using hair rendering and subjective evaluation

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Analysis of hair shine using hair rendering and subjective evaluation

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