Poster PDF / List of their other seminars
If you happen to be in Hong Kong, you might want to check out this talk by our Dr. Nelson Chu on the development of digital brush / ink technology held by the Open University of Hong Kong on 9th Nov 2016.
Poster PDF / List of their other seminars
Comments
We cannot emphasize enough the importance of stylus tilt sensing. If your graphics tablet doesn't sense tilt, apart from using right-mouse-button-drag, you can still choose to add a game controller in the mix - a cheap one can be had for under US$10. In our demo, we use a PS3 controller, because it's also equipped with a tilt sensor that can be used for paper tilt in Expresii. Since the P3 controller is not native to the Windows OS, we need some third-party software to make it work on the PC: MotionInJoy driver, Better DS3. You first install the MotionInJoy driver, which also comes with its own control mapping tool, but it's better to use the Better DS3 tool for easier mapping. If your game controller is native to PC, you probably can simply plug and play. To test the game controller we use Joystick Tester . We map the controller tilt to R and U values as shown in the Joystick Tester . The following is video showing how it works together: The non-tilt-sensing graphics tablet used was a Huion H420 (US$30). Its three buttons on the panel itself can be mapped to hotkeys of your choice. It's cheap and good, except that the battery compartment gets rusty and gives bad contact now. We have had it for one year only. Another downside is that the hover distance is very little compared to that of a Wacom. But for $30, it's not bad an option for those who on a budget or want a very portable graphics tablet - it's probably the smallest graphics tablet that gives pressure reading! And in case you also own a PS3 controller, here is the mapping we use. You can first press the 'Auto Fill' button to get a default mapping, and then modify it from there. It's mainly the SixAxis Tilt that needs to be assigned as Right Stick (X, Y).
I know many of you are artists and may not be too aware of the historical development in the use of Computational Fluid Dynamics (CFD) for watercolor-like digital painting. I think it's useful to give a summary here. Cassidy Curtis et al. was the first to apply CFD in watercolor painting [SIGGRAPH 1997]. He used what is technically called Explicit method (which requires taking small time steps) in solving the fluid equations. He was able to render one painting at 640 x 480 pixels in 7 hours on a workstation-class machine. At that time, fluid simulation was believed to be too slow for interactive applications.
interactivity, so he looked for alternatives. He finally adapted a CFD method called Lattice Boltzmann and the results were presented in his MoXi SIGGRAPH 2005 paper. If you take a closer look, you will find that Nelson's method produces more realistic ink dispersion compared to that of a usual Stam fluid sim, the latter being more like smoke in space than ink on paper. After Nelson resigned from Microsoft in 2011, he continued to improve the simulation method and that's what went into Expresii you see today.
Expresii is officially launched!! (ノ´ヮ´)ノ*:・゚✧Download Expresii 軟件下載 (for Windows only) It's been a long time. When MoXi was first unveiled in 2005, I was asked how soon it could become an actual product. I answered, 'could be two years'. In 2006, MoXi was licensed to Adobe, and I was even hired to do tech transfer. I was hoping MoXi would have good future there, but the story didn't evolve as I thought. Anyway, if they can't make it happen, we will. I know we all love free software but sorry that we need to start charging for the tool now (introductory price US$59), since it took a lot of time and effort to create a tool with such advanced algorithms. I think this is the most direct and healthy way for Expresii to grow without going down the path of showing ads or telling you it's free but then charging you in some funny way. Your financial support would determine if small guys like us can survive or if we are left with tools coming from big companies only . About ExpresiiExpresii is a ground-breaking paint app featuring:
Expresii is a successor of MoXi developed by Nelson Chu over the past four years with improved simulation and rendering. Expresii for Windows is now offered at an introductory price of $59 with trial license key available. Notes to Users/ReviewersHere are a few points we would like to make sure you are aware of:
重拾筆的感覺現在一般繪圖軟件,思想較近西方傳統,’brush' 一般就是用來‘塗’的,比較像‘刷子’。但東方毛筆是書寫工具,經多年發展表現力尤佳,東方繪畫的基礎訓練是書法,其正是要訓練操控筆的能力。在我們Expresii 軟件裡,您可以重拾筆的感覺:透過手的動作自然地做出不同的點、線、面。Expresii 的筆,也是眾多繪圖軟件中,最能充份利用帶側鋒感應的專業級電繪筆的。 水墨淋漓當然還有我們的水墨。我們是應用了流體力學來模擬水墨流動,以做到目前為止世界上最自然的實時水墨效果。 We use Computational Fluid Dynamics for our ink flow simulation to give you the most natural results. 突破像素局限現在的繪圖軟件還有個問題,就是圖不能放很大,放太大會看到一粒粒的像素。 所以我們一再革新,用混合向量像素(hybrid-vector-raster)的方式來儲存繪畫數據,讓Expresii 的圖可以放很大。 We use a novel hybrid-vector-raster representation to allow high degree of zooming in. 作者感言老套點講,製作Expresii 真是嘔心瀝血。現在終於正式推出了,儘管還有不完善的地方。
感謝【狐朦大叔】作者Tom 一直支持。他也剛出書了(用Expresii 畫),感覺是一起生了小孩。還有感謝一直支持的Shuen Leung, Mark Lam, 日本的 Kuroda-san ,和盧生、李生和最近認識的飯主等前輩的經驗分享和幫忙,還有Wacom 台灣總經理Martin的推介和其他高層的賞識,和其他曾經給予鼓勵支持的朋友。 從美國辭職回來已五年,也一直沒收入五年^。長期沒收入,在亞洲社會是很難理解的(一直以為李安只待家兩年,原來六年才對),我前幾天還真的被問 ‘還未找工作?’,也曾被問回來後悔否。其實在哪發展最好,難說,但肯定的是,在這邊比較近父母,還有可以在外婆的最後幾年多點看她。 2002年去北京發表虛擬毛筆的論文,時年二十五當是個交代。現在趕在四十歲前把Expresii 推出了,也算是個交代。我的青春都放在這電腦繪畫的研發了。 作為一個東方人,我覺得有責任去把我們最好的東西,承傳並發展下去。筆有千秋業! - Nelson Chu 2016.07.24 ^ 感謝去年澳門的學會請我演講給了點講費,幾年前香港Poly 的Wilson 找我也有一點點講費 Today, often digital painting s are done in less than 4k resolution, and you might be further limited to e.g. 2k when you use computationally-intensive tools like Corel Painter's watercolor. If you zoom in, you will see big fat pixels. You can't print it large - it looks fine on a computer screen but printing it on a piece of paper would make the resolution insufficiency prominent. In fact, even our screens are getting higher and higher resolutions. In 2007 , Sony showcased a 4k projector as a very advanced piece of equipment - but now it's no surprise if you see a 4k screen around, be it desktop or mobile. We're more urged to address the resolution hunger than ever. A Pure Vector Approach as Solution?In late 2014 the new painting app Mischief made a splash being acquired by The Foundry. Mischief's infinite zoom is their core competence over other painting apps. However, infinite zoom has always been a feature of vector-based representation - and Mischief is in essence a vector program. The issue was just that most previous vector-based tools are more like a designer's tool rather than a painter's making it hard to do painting fluidly. BTW, infinite canvas is also not new, as at least Rita offered such feature years ahead in 2006 and is vector-based too. Like in most vector-based tools, the lines made by Mischief are crisp (except for the one brush that gives a dithering effect, which is another kind of crispness if you will), which is good for line arts or sketches. But if you regard the artwork as a 'painting', these lines are too clean. You can add more strokes to get more painterly, but with too many lines the system would slow down as details created by every line has to be redrawn every time you pan your screen - even with the advanced Adaptive Distance Field (ADF) tech behind it and that it is said to utilize the GPU for accelerated processing. Technically, if the number of strokes is N, the redrawing is of order O(N). * Previously we covered Adobe's vector approach to do watercolor on the ipad in this blog entry. Essentially it also looks good on spec, but not that great in practice. When enlarged, you see many individual polygons overlapping each other (below). Personally, I don't think it looks too pretty nor natural, not to mention the added burden of rendering thousands of polygons. (๑´╹‸╹`๑) A more Painterly ApproachIn Expresii, we take a rather different approach to the fat-pixel problem. Our representation is somewhat between pixel- and vector-based. If the canvas/paper resolution is M, our redrawing is of order O(M), independent of N. This is a property of pixel-based tools. However, our magic is that we are able to zoom in a lot - a lot more than what existing pixel-based programs offer given the same amount of paint data. We may call this ' Good-Enough Zoom' (vs. Infinite Zoom). This is somehow akin to audio sampling - our ears can only hear up to 22KHz so sampling up to double of that namely 44KHz is 'good enough'. In real world painting, someone might draw a tiny figure, but he or she is not likely to add every detail to that figure. As a viewer, if you can zoom in so that you can see the fibers in the paper, that's pretty enough too. Do we need infinity zoom? For cases like showing the world reflected in a girl's eye, yes. For such cases, people without infinite zoom could simply make drawings at multiple scales and switch between the drawings (which is what people currently do) so it's not really the end of the world. In Expresii, we don't claim to do everything. We can't do infinite zoom. Our canvas/paper is finite, which is actually closer to a real-world painting experience - you have a frame to anchor your work. Instead of infinity canvas, Expresii offers extendable paper. Our end result is a rather organic looking painting that we can zoom a lot into. The strokes and flows are extremely natural - unprecedentedly natural. GPU AccelerationNot only our ink flow simulation utilizes the GPU power. Our rendering engine (which we call Youji 有極 for marketing purposes ;-) is also GPU accelerated. Given a decent graphics card, you can pan and zoom silky smoothly. BTW, we are really glad to see a steady growth of GPU hardware. We used to require an expensive discrete graphics card, but now even an integrated GPU can do the job fast enough. Interesting side note: When Nelson was speaking at the Adobe Headquarters in San Jose back in 2006, a Senior Photoshop Scientist was bashing the use of GPU. I think he was like laughing at a person building the Internet at its early stage - hey network is so slow, why bother. Well, if you can see the potential early, you will be heading in the right direction. Now, even Photoshop itself is getting more and more GPU acceleration. Best of both WorldsArticles about Mischief often praised it taking the best of both worlds of vector and raster. Mischief promised 'the richness of pixel-based brushes'. Yet in reality we don't really find the promised richness of textured brushes like those in Corel Painter or Photoshop. Furthermore, operations like smudging or blurring, which are trivial for raster-based tool s, are not possible or at least the maker still can't demonstrate such possibility^. In contrast, Expresii really gives you the richness of pixel-based tools. You can still blur a stroke (we don't have a separate blur tool but you can do so by stroking with a clear brush or use our new Pusher brush mode), not to mention our extremely natural ink flows efficiently executed on the GPU all thanks to its pixel-based nature. However, Expresii also has its vector personality - you can zoom in a lot as if there's no pixels. We believe Expresii is a true innovation in the history of digital painting, really 'taking the best of both worlds'. Give it a try today and see for yourself! Reference: [1] from their paper "Industrial-Strength Painting with a Virtual Bristle Brush", 2010. [cached copy] * In ADF there is only one distance field to be sampled but the sampling needs to be more refined when a new stroke comes in, thus causing the complexity to be O(N). However, in practice Mischief is performing quite fast even with large number of strokes.
^ Update 2016-12: development of Mischef seems to have stopped. Founder and Chief Scientist Sarah Frisken even left the new company founded due to the Foundry acquisition. Head of that company Chris Cheung , who moved from Autodesk's Sketchbook, also left the company. Update 2019-10: madewithmischief.com is finally closing in Dec 2019. I was recently asked why one would want to paint digitally. The two most common reasons are:
And what are the cons of digital painting? Long time ago, I discussed with Wucius Wong on this. Wong suggested two main concerns:
As a software developer, there's still things we can do. We'll discuss digital painting tech innovation in our next blog entry. 還有就是,畫家如果靠賣畫為生,傳統畫較易賣高價。相反數位(digital)畫,大家覺得打印出來的沒那麼有價值。其實打印出來的東西也可以賣高價,如罕有的郵票。還有傳統版畫,也是重複印出來,但通常限量,畫家每幅記號並簽名。大家大不了就把你的電腦畫用最高檔的(抵擋的放久了會褪色 >x<)墨水打印出來並簽名,然後把原檔刪了就可以'物以罕為貴’了。 Ease of change - good or bad thing? 容易修改熟好熟壞?Wucius Wong is one of the few senior (Chinese) ink painters who does make use of computer technology. He exclaimed to Nelson - it is too easy to make changes in your digital art! 王無邪 (Wucius Wong) 是少數很關心我們Expresii 開發的傳統畫家,他自己也很早就有用電腦輔助作畫。他說我們用Expresii作畫,太容易修改了! It's true that in traditional ink painting, it's much harder to make afterthought changes and thus masterpieces don't come by easily. But when it is easy to make changes, one might be trapped to spend too much time keep making changes. 傳統繪畫難修改,所以精品難求。但就純粹作畫者來說,容易修改應該是一個優點。但這‘優點’有時就帶來更多‘麻煩’ -- 就是改來改去,一幅畫拖太長。 有趣的是Wucius 也講過^ Interestingly Wucius once said^: When the painting is still there, there's always a temptation to adding a line or a dot to it. I think all artists would do the same thing naturally. 大家也有改來改去的煩惱嗎?以下我也是因為電腦畫太容易修改,所以改來改去。老人耳前的髮絲,都很多考量。畫粗一點好像較好表達老人‘幹活’的情況,畫細一點優美點但會不會給人太年輕的感覺? If you're a digital painter, do you find yourself keeping changing little details in your art pieces? For me, for instance, I kept changing details on the hairs in from of the ear, trying to find a look that better represent this old lady: 有人說一幅畫磨太久,不如把時間花在下一幅。Some say you should spend time on your next piece rather than lingering on your current one. Anyway, here's the Old Lady 'final' version: Check out a video showing the process of creation: ^ In video 'Mountain in the Mind', Minneapolis Institute of Art, 1986.
Now in Expresii you can assign a color to a particular brush using the color tag like this: It's more beautiful and easier to see which brush you're holding. It also works perfectly along with Wacom's Pen ID feature. BTW, You may also noticed the latest version of Expresii has Quick Access Panels for brushes and papers too (in addition for Colors). Color Rings are not new. In fact, we had them back in the MoXi prototype more than 10 years ago: Years later Wacom’s Intuos 4 (came out 2009) also incorporated similar color rings like these: We did meet with Wacom's people in the USA (along with Adobe folks) and gave them a copy of MoXi in 2006. Maybe they got inspiration from us for the color rings? I dunno. Anyway, please don't say we copied Wacom's design, because we have this way before they do. ;)
Since version 2016.06.19 we have added several new papers for you to play with: You can zoom in to see the amazing details: Existing users would need to do a Factory Reset to the Paper Presets in order for the new default papers to appear, as illustrated in the figure. Update: If the above doesn't work for you, try going to Start Menu>Expresii>Factory Reset, which resets the whole app (close Expresii before doing this reset). Enjoy the new papers and let us know what you think!
CES (Consumer Electronics Show) AsiaRecently we've been working closely with Wacom and our latest show was at CES Asia held last week in Shanghai, China. This is the second year we have CES Asia in addition to the CES in the US. Wacom is promoting their Pen ID feature and Expresii was used to show off that. Essentially, Pen ID allows you to associate your brush settings to a particular physical pen so that you can simply switch the physical pen when you want to switch your virtual tool . Here is a demo: One of the tablet models we used was the HP Elite X2, among others from Toshiba and Lenovo. Check out the following amazing flow demos in which the HP wa s used .
Wacom's Connected InkOur Dr. Nelson Chu was also invited to be a Panelist at Wacom's event Connected Ink to discuss the future of digital ink. It's held on the 93rd floor of Shanghai World Financial Center , one of the world's tallest buildings during the second day of CES Asia. Expresii attracted many of the participants, including both hardware and software makers. The flowing ink, which you can control by tilting the tablet itself, is simply amazing.
Wacom has been pushing forward the Digital Stationery Consortium as a joint movement around “ink of 21st century”. We are totally aligned with this development. In East Asia, we have been using a writing brush to write for thousands of years. Today calligraphy is a still big part in our lives. The following is a piece of calligraphy '文房具‘ meaning ’ Stationery‘ in Japanese (yes, those are actually Chinese characters ;-) done with Expresii . Notice the high quality rendering that other apps just can't match. Expresii is the best tool I've ever used for calligraphy and ink painting! - Nobutaka Ide, Sr Vice President, Wacom In deed, the strokes and flows in Expresii are so natural, people seeing it for the first time are often in awe. In conclusion, now hardware and software are finally coming together to make advanced creative tool like Expresii easily accessible!
Asia is full of events! Recently Wacom has picked up Expresii in many of the shows they're participating. And this is Microsoft's event WinHEC 2016 taking place in Shenzhen and Taipei: Next month we'll be at CES Asia. See you there! Register now to take advantage of the extremely low registration fee of RMB50 or US$7.7! Download Expresii beta to try this amazing app yourself: http://bit.ly/1jUNMXo
|
Expresii 寫意Previous Posts
|