Virtual objects are timeless—they are rarely left derelict for prolonged periods, whereas object degradation is a universal phenomenon in reality, giving a strong impression of the lapse of time. Hence, the aging of virtual objects is a vital topic in the pursuit of physical realism in the area of Computer Graphics. 

In fact, many developments in the process of weathering have been offered to depict outdoor objects as having suffered rain and wind damage. Especially, metallic surface rusting is a widespread degradation phenomenon featuring varied manifestations, and hence there exist many known weathering methods targeted at metallic surfaces.  

However, most of the existing methods do not consider the effect of rust-preventive paint, which is usually applied to the real metallic surfaces. Besides, few metal weathering methods have not supported 3D deformation, which is also required to express realistic coating film deterioration. 

In this thesis study, a novel procedural method for weathering coated metal objects is proposed. In this method, a coated surface is imposed on a 3D triangular mesh. The method allows for the mechanical behavior of deteriorated coating film and deforms the mesh model to express cracking and peeling. 

We think much of directability, that is, expertise that enables the systems to be intentionally controlled. In this method, it is possible to control the progress of deterioration by designating the area easy to peel.


We try to express the deterioration of coating films by automatic computing rather than by applying measurement data, so this study is not phenomenological. Of course, we aim for a modeling method that simplifies computation, but we put more emphasis on mechanical theories, so this method is physical rather than artificial.


NameAffiliationWeb site
Akinori IshitobiKeio University
Masanori NakayamaKeio University






  1. Akinori Ishitobi, Masanori Nakayama, Issei Fujishiro: “Visual simulation of weathering coated metallic objects,” The Visual Computer (Special Issue of CG International 2020), August 2020 (online publication) [doi: 10.1007/s00371-020-01947-w]. (Preprint/DemoMovie/Presentation)


International presentations
  1. Akinori Ishitobi, Masanori Nakayama, Issei Fujishiro: “A deformation method for simulating coating degradation while taking mechanical behavior into account,” 2019 International Conference on Cyberworlds (CW), Kyoto, Japan, October 2―4, 2019, [doi : 10.1109/CW.2019.00066]. (Preprint/Movie/Poster)
Domestic presentations
  1. Issei Fujishiro, Akinori Ishitobi, Masaru Ohkawara: “Computer graphics for building photorealistic cyberspaces,” KEIO TECHNO-MALL 2020, No. 51, online, December 18, 2020 (in Japanese). (Material by Ishitobi: Video/Poster)
  2. Akinori Ishitobi, Masanori Nakayama, Issei Fujishiro: “Visual simulation of weathering coated metallic objects,” invited talk, in Proceedings of Visual Computing 2020, pp. 15:1―15:4, Online, December 2―4, 2020 (in Japanese). (Preprint)
  3. Akinori Ishitobi, Masanori Nakayama, Issei Fujishiro: “Visual simulation of aged coating degradation,”  in Proceedings of the 81th  National Convention of International Processing Society of Japan, Vol. 4, pp. 125―126 (2ZC-08), Fukuoka University Nanakuma Campus, Fukuoka, March 14―16, 2019, Student Encouragement Award [IPSJ Digital Library] (in Japanese). 


  1. Grant-in-Aid for Scientific Research (A): 17H00737 (2018-)

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