MoXi: Real-Time Ink Simulation
Next-Generation Digital Painting Technology

Last update: 20.09.2007

one stroke leaf


[Publication] - [Talks] - [Videos] - [Images] - [publicity] - [Links] - [FAQ]

We present a physically-based method for simulating ink dispersion in absorbent paper for art creation purposes. We devise a novel fluid flow model based on the lattice Boltzmann equation suitable for simulating percolation in disordered media, like paper, in real time. Our model combines the simulations of spontaneous shape evolution and porous media flow under a unified framework. We also couple our physics simulation with simple implicit modeling and image-based methods to render high quality output. We demonstrate the effectiveness of our techniques in a digital paint system and achieve various realistic effects of ink dispersion, including complex flow patterns observed in real artwork, and other special effects.

Nelson S.-H. Chu and C.-L. Tai, MoXi: Real-Time Ink Dispersion in Absorbent Paper, ACM Transactions on Graphics (SIGGRAPH 2005 issue), Vol. 24, No. 3, August 2005.
 Main technical paper (16MB)

Nelson S.-H. Chu, Making Digital Painting Organic, PhD Thesis, HKUST, August 2007.

 PhD Thesis (20MB)

Supplementary Technical Materials
 Implementation details and issues
 Implementation sketch
 Cg code for LBE water flow simulation
 Render-pass chart

Non-Technical Materials
 Draft text for art exhibition
(in Chinese & English) (190KB)
(in Chinese & English) (1.4MB)


Jun. '05

Invited talk at Hong Kong ACM SIGGRAPH Seminar

Jul. '05

ICMMES 2005 -  Slides (32MB)

Aug. '05

SIGGRAPH 2005 -  Main Slides (38MB)  -  Impl. Sketch Slides (6.2MB)

Feb. '06

Invited talk at Macau Uni. of Sci. & Tech., Macau

Aug. '06

Talk at Uni. of Minnesota, Minneapolis

Oct. '06

Demo and talk at Adobe Headquarters, San Jose

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Video Demos

To play .wmv in QuickTime on a Mac, please click here.


Latest Teaser (2007)
 [wmv] 1.5 min. Teaser (8MB)

SIGGRAPH Video (2005)
720x480 (42MB)
360x240 (8MB)

720x480 (72MB)


Bunny (2005)
[DivX AVI]



Special Effect (2005)
[DivX AVI inside]
   Flare & wash (3MB)

Hong Kong China calligraphy  digital calligraphy demo  UST calligraphy  UST 15th Anniversary calligraphy

Calligraphy (2006)
   Hong Kong China (4.6MB)
   Variety (3.2MB)
   UST 15th Anniversary 


Doggie (2006)


Fishing Village(2006)
  avi icon Fishing Village (41MB)

Digital Watercolor:
Wetting an Existing Image

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非水非墨] [Wallpaper] [More]


筆有千秋業 筆有千秋業  calligraphy for new year  lan orchid  moxi logo
dragon mountain  tao



[Sneak Peek of Western Watercolor Extension @ CG Society]

Check out Nelson's Blog for more recent artwork & news.

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Live Demos
 SIGGRAPH 2005 [Cassidy Curtis' shots 1, 2] [Cat by Kyoko Murakami]
 Innovation Expo 2005, Fall 2005, Hong Kong [User Artwork]
 - Photoshop User Group Meeting, Oct. 2006, San Jose
 - ITU Telecom World 2006, Dec. 2006, Hong Kong 
 - SIGGRAPH 2007, Aug. 2007, San Diego  new
 Innovation Expo 2007, Sept. 2007, Hong Kong   new

TV Broadcast:  
 RTHK programme 專之驕子II - 數碼新視域, August 2005 (in Cantonese) [Local Copy]

 Face to face with Nelson Chu,, Sept 2005 (in Chinese)
 - 產水墨軟件入選IT界奧斯卡, SingTao Daily, Oct 2005 (in Chinese)
 - WACOM 壓力感應筆變身數碼毛筆, Wacom Case Study, Nov 2005 (in Chinese)
 - Calligraphic Brush Gets Makeover, Genesis, Feb 2006
 - 最強の毛筆シミュレーションソフト現る?, by 大賀葉子, May 2006 (in Japanese)

Web News:
 TRNprimidislashdot, cgchannel, 3DHelper
(in Chinese)

Forum Threads:
 hxsdmy3dbox, mwopus, idmt 
(in Chinese)


  • Oriental Art Suppply - see how artist Ning Yeh does those magical strokes
  • Gao Xinjian painting collections
  • A company that sells new art materials (Simpl. Chinese)
  • An article on new developments in ink painting
  • An article on the term MoXi, which literally means 'InkPlay' (Simpl. Chinese)
  • An article on the possibilities of using new paper for new effects (Trad. Chinese)
  • Virtual Chinese Brush - our previous project
  • Corel Painter ?one of the most popular commercial digital painting tools. You can compare yourself!


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保留傳統,只有發展才能保留,不發展就不可能保留。? 吳冠中
To keep the tradition is to develop the tradition. - Wu Guanzhong

'... for at this point, the focus is not on succession but on extension of the tradition.' - Wucius Wong, The Tao of Chinese Landscape Painting, p.137.

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