手写笔技术大不全
巡禮：手寫筆 ?+ 延伸閱讀
http://augix.me/2016/01/%E5%B7%A1%E7%A4%BC%EF%BC%9A%E6%89%8B%E5%86%99%E7%AC%94/
http://www.ticktakashi.com/2014/05/wacom-vs-n-trig-modern-comparison.html
就算當年喬布斯還活著的時候，一些人們也不顧“教主”的倡導，在iPad上面配備一個手寫筆。這種手寫筆一般分為兩種：藍牙驅動的定位筆或者單純模仿手指的電容筆。由于iPad當時生來就沒有考慮過用筆，所以體驗并不是很好。
西方不亮東方亮。三星用自己的Note系列手機，尤其是那只表現不錯的筆，吸引了很多人的興趣，也因為這支筆，收獲了不錯的銷量。同樣的，配有手寫筆的Surface電腦，也是因為有這支筆，被很多人認為是核心賣點之一。
四面楚歌，不，八面玲瓏的庫克自然沒有那么死心眼，很快，iPad也有了自己筆。
就像一出恢弘的歌劇，終于，所有的主角悉數登場。目前，在高端點的手寫筆（排除沒啥用的電容筆）領域，主要的派系為：以微軟收購的N-Trig系列（用于微軟自家Surface產品）、以Wacom為代表的EMR（電磁感應輸入技術，Electro-Magnetic Resonance）和AES（主動式靜電感應技術，Active Electrostatic Solution）系列、蘋果的Apple Pencil（蘋果自家黑科技，目前找不到詳盡的資料介紹）。
（現在投身做手寫筆的大廠還有：Atmel、Synaptics等。但是由于市場占用量太小，就不再論述。）
于是問題就來了……
這次，就來對比一下主流的這幾項技術。
Warning：文章中夾雜了大量物理常識（其實連筆者也不懂），請讀者選擇性食用。如果只關注使用體驗上差別，請直接跳轉到文章后半部分。
Wacom EMR
在手寫筆的領域，Wacom絕對是壟斷性的存在。之前曾經挑戰過Wacom的公司，差不多都自掛東南枝了。譬如曾經也風生水起的“友基”，現在在Wacom各種高中低產品面前也顯得黯然失色。
當然，Wacom的成功，也多半歸功于這個EMR技術。
毫無疑問，Wacom最成功的數位板產品線當推影拓（Intuos）系列。影拓系列采用的都是EMR方式的手寫筆。
采用EMR方式的手寫筆，如果不考慮筆身上面設置必要的按鈕（啟動程序等功能需要藍牙連接），本身是可以無電源使用的。這也是這個技術區分于其他所有主流手寫筆的最重要特點。事實上，很多廉價國產平板采用的筆都是這個技術的，其筆身沒有設置任何按鈕，也不需要電池驅動，譬如酷比魔方iwork11系列。
EMR的工作原理
在屏幕下方有可以探測到EMR筆活動的電磁感應板（圖片中EMR傳感器所在位置），在感應板上面縱橫分布著線圈。高中物理常說，“磁生電，電生磁”，隨著筆的移動，在通電的感應板所產生的磁場范圍內，筆中的共振回路能夠積蓄微弱的電能。當筆積蓄到能量后，控制回路就會停止向循環線圈提供電流并把循環線圈接通到接收回路。此時筆所積蓄到的能量會通過共振回路的自由震蕩，將能量從筆尖的線圈處傳送回感應板。在將能量傳回電磁感應板之后，控制回路首先通過對感應板上循環線圈的掃描，從而初步檢測出筆的大致位置。接下來再對筆周圍的多個循環線圈進行掃描，并對檢測出的信號進行計算，即可十分精確地計算出筆的座標值。
通過以上的過程，并不斷進行計算，系統不僅可以得到筆當前的坐標，還能獲取筆的移動速度等數據。
壓感的實現，是通過筆內部的、在筆尖后端的電容器實現。當施加壓力的時候，筆尖會向筆里面運動，從而導致電容器正負極之間的距離變化，從而改變電容，實現了對于壓力的感應。
現在的平板電腦，將顯示屏、電容感應屏幕和電磁感應板堆疊在一起，從而實現EMR手寫筆和手指都能夠操作。
EMR的特點
EMR技術的最大特點就是成熟。作為久經考驗的手寫筆技術，EMR非常可靠，也意味著廉價。所以EMR技術幾乎成為入門級別產品的標配。并且由于不需要電源，EMR的筆可以做的很細，非常適合需要在機身開筆槽的機器，例如三星的Note系列手機。
經過多年的進化，現今EMR技術的筆一般都達到2048的壓感級別。在市場上，應該屬于最高一檔壓感級別。
另外，EMR筆都支持懸浮操作，即筆尖距離屏幕一定距離也可以操作。Wacom的EMR技術讓懸浮操作延遲較低，而微軟的N-Trig雖然也做到了懸浮操作，但是操作時候延遲很大。這個問題在寫字或者作圖的時候，想對準一個地方的時候，使用N-Trig的筆往往有點麻煩。
但是由于EMR的工作原理，必須在屏幕上放置感應器，所以會增加整個屏幕的厚度。這也是一些追求極致的平板所不能接受的問題（Surface Pro 3放棄在前兩代使用的Wacom的筆的原因之一）。
此外，EMR技術在邊緣準確度上有很大問題（Surface Pro 3開始微軟放棄Wacom的EMR筆技術的第二個原因）。EMR技術在小屏幕上表現良好，譬如三星Galaxy Note系列的手機屏幕；但是在平板這種屏幕尺寸較大的設備上，其邊緣的準確度會明顯下降，甚至會出現邊緣筆跡斷斷續續的現象。其實這個問題也存在于數位板上面，但是由于數位板沒有屏幕，所以即使有偏移和視差（屏幕上顯示的位置和真實筆尖在屏幕上的位置的差別），也表現的不是很明顯。
總結來說，由于Wacom在整個手寫筆領域的事實上的壟斷地位，EMR是其主推的一個技術。EMR成熟、可靠，并且價格低廉，是入門級別很好的選擇。
補充說明一下，根據網上的反饋和調查，不同操作系統對于手寫筆的表現都有影響。在Android系統下，EMR筆的視差和延遲都明顯比Windows下好一些。
N-Trig
在Wacom抱著EMR這棵枝繁葉茂的大樹不思進取的時候，N-Trig技術以其更好的屏幕邊緣精度和較小的時差，被很多廠商看好。當然被看好的結果大家都知道，微軟：買買買！
在微軟收購N-Trig之前，N-Trig大有和Wacom平分秋色的感覺。包括Thinkpad的一些平板都在嘗試使用N-Trig技術的手寫筆。然而，自從微軟收購了N-Trig之后，這個觸控筆技術就變成了微軟Surface系列的“御用”產品。
N-Trig的工作原理
事實上，在業界，類似N-Trig和Wacom AES等有源手寫筆被稱為主動投射式電容筆（Active Projected Capacitance Stylus ，Active P-Cap Stylus）。雖然具體實現上有所差異，但是總體技術原理上差別不大。
首先，有源的手寫筆不斷發出低頻信號（頻率一般在30～70KHz之間），信號中包含筆尖所感受到的壓力、筆的按鍵狀態和筆的ID序列號等信息。通過上面的結構圖可以看出，對于壓力的數字化，是通過筆尖壓迫快門，促使快門遮擋LED的光線，從而影響在LED對面的檢測器的受光量和感光位置，進而計算出筆尖受到的壓力。
其次，在機器屏幕上，有網格狀的投射式電容傳感器，負責整個觸摸和筆的感知。這些網格狀的電容傳感器排線分組連接到若干個控制器上，這若干個小的控制器又連接到一個主控制器上。在工作的時候，主控制器負責控制和管理若干個小的控制器，與這些小的控制器進行數據交換，并收集這些控制器傳過來的筆或者觸摸的位置信息，同時也將收集到的所有數據處理后提交到主板的相應接口，從而完成對于觸摸或者筆的工作流程。
在這個環節，其實每個廠家處理并不相同。有一些廠商，例如Atmel，采用雙向傳輸模式，即筆和傳感器之間可以相互進行數據交流。而N-Trig則不同，是采用了單向傳輸模式，筆只負責發送響應的低頻信號到傳感器，不再具有信號接收功能。
N-Trig的特點
自然，相比于之前說過的EMR模式的筆，N-Trig的筆復雜了很多，所以價格上也水漲船高。根據商業規律，大部分廠商都是希望通過配件來賺取更多利潤的，而不是僅僅通過主機。一旦配件的成本太高，勢必擠壓了廠商原本的利潤空間。所以即使是在微軟收購N-Trig之前，N-Trig的筆也多出現于Thinkpad這種高端機型上面。畢竟只有高端機型，才有足夠的利潤空間，即使配件的價格稍微高一點，消費者也不會那么在意。
N-Trig的最大特點是將觸摸和筆識別結合在了一套系統上，屏幕上只需要放置一層感應層就可以完成。從而減少了屏幕厚度，也減輕了重量。同時，屏幕層數越少，光的折射效果便越不明顯，就可以讓視差也隨之縮小。
當然，實際體驗上來看，N-Trig的筆的確在很大程度上解決EMR筆的視差偏移和邊緣靈敏度問題。當然，如果嚴格來說，一點偏移都沒有的筆是不存在的，尤其是筆尖的角度較為傾斜的時候。
筆的響應速度方面，N-Trig較比EMR并沒有太大的優勢，甚至可以說在相應的延遲時間上，EMR技術更短，使用過程中表現出來就是感覺筆跡更“跟手”。當懸浮的時候，N-Trig的筆反應靈敏度立刻降低，甚至有明顯的滯后感覺。
一直以來，手寫筆不被人看好的很大原因是在屏幕上有一種在“玻璃上寫字”的感覺。在Surface Pro 4的筆上，微軟也特別加入了硅膠之類的筆尖，從而大大增加了使用時候的摩擦力，讓人真的又一種寫在紙上的感覺。這點其實非常重要，就像日常購買鋼筆一樣。一般人首先都是考慮手感，看寫出來是否順滑但還要不至于滑得失控，然后才回去考慮出墨是否流暢等其它方面。
在Surface Pro 4的筆上，微軟終于回歸了1024級別的壓感。早在N-Trig在被收購前，就有256和1024這兩個壓感級別。但是比較市面上大部分EMR筆都是2048級別（事實上，2015年開始大量上市的Wacom AES技術的筆也均為2048壓感級別），N-Trig不知道能不能盡快趕上。
另外就是畫線抖動的問題了。這也是從Surface 3時候的老生常談了，在慢速畫直線的時候，N-Trig的筆畫出的線條就是仿佛手抖一樣的波浪線。這個問題，在Surface Pro 4的筆上依然存在。
當然，作為有源的手寫筆，需要安裝電池。盡管Surface的筆采用了最細的AAAA（9號）電池，其體積和重量也都算手寫筆里面較粗的。還好，每個人對于筆的粗細、重量甚至重量的分布都喜好不同。不過由于體積的限制，Surface的筆就不可能類似很多傳統的手寫筆一樣，在平板機身上開一個筆槽。“設計成內置電池，充電的不就好了么？”太細的筆可能造成筆內電池容量非常不理想，影響整個筆使用時間（沒錯，說的就是那個設計得那么細、卻仍沒辦法放在平板內、還沒有筆夾的Apple Pencil）。而且能換電池的設計，也并不是那么不方便，雖然那群老外根本就沒有想過9號電池在中國是多么不好買，但相信隨著各種手寫筆的普及，9號電池一定會出現在樓下小賣部的柜子里。
2016年1月30日更新：至于為什么Surface Pro 4的筆可以用在Surface 3上面，但僅能提供256級別壓感，由于N-Trig的資料并不是那么齊全，只好自己分析一下。N-Trig的壓力感知是通過筆尖的快門遮擋LED光束完成轉換成數字信號的，并通過低頻信號發射出去。但是由于接收和處理壓感信號的控制器并不具備處理1024級別壓感的能力，所以只能以類似“兼容”模式處理256級別的壓感信號。類似于在720P分辨率的屏幕上播放4K分辨率的視頻，雖然視頻分辨率非常高，但是由于接收視頻信號的顯示器分辨率的限制，只能最終以720P的分辨率展示出來。
Wacom AES
還好，在N-Trig之類的廠商的壓力下，Wacom也終于推出了新的手寫筆技術。
其實在很早，Wacom也有過一個帶電源的手寫筆技術，不過據說這項技術Wacom并不看好，將其賣給了基友廠商——友基。不過這大多是坊間傳聞而已。
在最近，Wacom開始推出了主動手寫筆的產品。在早期（2015年年初），有一些采用了AES技術的產品，如東芝的部分二合一設備，但是由于那時候Wacom技術不成熟，不同型號的AES筆甚至不能互換使用，這些采用Wacom AES的平板更像是在做Wacom的試驗品。但是在2016年初，Wacom推出了完整的AES手寫筆系列，并據此推出了Bamboo Smart手寫筆。這支筆可以兼容市面上大部分采用AES技術的平板電腦，甚至一些剛剛推出的平板電腦。從而繼續奠定了Wacom在此領域的壟斷。
AES的工作原理
在Wacom的網站上，并沒有詳細介紹AES的基本原理。看來對于這個技術，Wacom還有所保留。不過根據Wacom提供的宣傳冊，應該類似之前提到N-Trig的模式，可能具體實現有所差別。
AES的特點
從2016年初這個時間點上來看，AES都提供了和EMR技術相同的壓感級別，達到了2048級別。
AES技術，相比于EMR技術，大大提升了屏幕邊緣的準確度，并盡量減小了視差。在接下來的文章中，將會通過對HP Elite X2 1012這款二合一設備的體驗感受，來具體分析AES技術，敬請期待。
和N-Trig相似，但是AES提供了2048級別的壓感。雖然對于普通人，256級別的壓感完全足夠，但是對于畫師來說，2048才是真正的利器，甚至專業級別的畫師需要4096級別的壓感。
同樣的，AES的筆也可以提供多種材質的筆尖，從而增加摩擦力。但是貌似目前上市各種AES技術的手寫筆大部分還是光禿禿的普通筆尖，寫在屏幕的玻璃面板上體驗還是不那么好。
雖然各方面都類似N-Trig技術（當然這兩種筆是不能互換的），AES的筆跡更加“跟手”，當進行懸浮操作的時候，光標較比N-Trig反應更為靈敏。
不過，雖然AES增加了邊緣的準確度，但是在畫直線的時候，仍然會有N-Trig類似的波動，而且波動甚至比N-Trig的還要大。
此外，為了省電，AES筆會類似一些藍牙鼠標，在長時間不用的時候自動關閉，當筆尖接觸屏幕的時候再再次開啟。這樣雖然達到了節電的目的，但是顯然N-Trig這種一直保持開啟狀態的筆更讓人覺得舒服（Surface Pro 4的筆已經改為自動休眠，拿起時候感受到加速度自動開啟）。據說2016年的新機型一些AES的筆也改進了電量管理，也是將筆設置為了常開狀態。屆時將配合HP Elite X2 1012的使用來驗證。
總結來說，AES是Wacom為對付N-Trig開發的一套非常不錯的技術。和N-Trig一樣的精確度和視覺誤差，?有比N-Trig更好的壓感和反應速度。如果Wacom繼續改進AES技術，相信將來一定是大部分手寫筆的首選技術。
目前看來，按照Wacom的產品線，Wacom看家產品數位板還采用EMR技術的筆，證明AES還是需要一定時間才能替代EMR的。Wacom也宣稱，即使采用了AES技術，整個手寫筆系統的成本依然低廉。可以預測，在2016年，大量國產的千元價位的平板電腦，都會逐步采用更加方便的AES技術的手寫筆。
Apple Pencil
蘋果至今沒有公布任何關于Apple Pencil的技術細節。
Apple Pencil的特點
按照蘋果的秉性，不爭第一，只求最好。一般蘋果推出的產品，都是技術更成熟一些，用戶體驗也稍微更好一些。尤其是到了廚子庫克這一代，不激進的蘋果推出產品的態度越來越沉穩。
當然，根據各方面的評測和信息匯總，蘋果這支筆，單純從壓感上來說，也就是256級別。不過Surface的信徒們也不要笑，一年前，Surface的筆也只有256級別的壓感。新技術的第一代產品，蘋果和微軟一樣，都不愿意步子那么大。
但是單純從體驗上來說，Apple Pencil應該是最好的手寫筆之一。
當使用Apple Pencil的時候，iPad Pro和Apple Pencil之間就以240Hz的采樣頻率交換數據，所以即使在非常快速的書寫的時候，也基本沒有“跟不上”的感覺。而N-Trig技術的筆的采樣頻率僅有140Hz。
Apple Pencil的定位、視差等問題也基本解決。在慢速畫直線的時候，也不會有任何波動。邊緣準確度和靈敏度都很好。
另外，這支筆支持傾斜角度，從而輔助一些軟件，畫出不同的效果。筆尖也有摩擦感，不會太滑。
但是，很多人并那么不喜歡Apple Pencil。首先這支筆太細長，造成內部電池容量很小。號稱12小時的續航遠遠達不到，很多人抱怨說是基本是一天一充。雖然Apple Pencil看似可以隨時插到iPad的Lightning插口上快速充電，但是這種方式非常不優雅。單獨購買一個充電底座，似乎也完全沒有必要。自己的Surface 3的筆，隨機附送的一節9號電池（超霸電池），在9個月的使用時間中，寫了大量OneNote文檔，標注大量PDF文檔，至今卻仍沒有換過電池。于是想起小時候，睡覺前，媽媽總會問一句：鉛筆削了么？鋼筆灌水了么？用Apple Pencil，還真的經常會被沒電困擾。還好，官方說，充電15秒，可以使用30分鐘。
總結來說，Apple Pencil是一支非常棒的筆。雖然蘋果都不好意思透露其壓感級別，但是配合iOS不錯的軟件優化，仍然效果很好。蘋果為了做廣告，請來一大票藝術家拿著畫畫。其實單從不愿意透露的壓感級別來說，Apple Pencil并不適合畫畫，相反，用Apple Pencil寫字、注釋PDF文檔、記錄OneNote筆記，書寫體驗甚至超過了大部分的Android和Windows平板。但是，由于iOS在生產力上的先天性不足，自己看文檔還好，如果涉及到了“文檔批注->批注文檔郵件發送->根據批注修改文檔”這種常見的工作流，iOS糟糕的生產力提供絕對會成為公司開除一個人的理由……
總結
顯而易見，雖然Wacom還沒有在自己的數位板等專業的產品線上用AES技術替代傳統的EMR技術，但是如今大部分筆都開始向有源方向演進。無論是上面說到的Wacom、N-Trig還是蘋果，還是依然在不斷努力的Atmel、Synaptics，都已經將有源的手寫筆作為自己發力的重點。
采用有源的手寫筆，好處顯而易見。除了能夠提供更好的使用體驗，還可以為筆加裝藍牙模塊，從而通過按鍵實現特定的功能，這點在Wacom最新的驅動軟件中已經實現，按鍵的功能也可以自定義。
同時，手寫筆的表現，還跟操作系統有很大的關系。總體上來說，Android對于手寫筆的處理好于Windows。
綜上所述，Wacom AES是比較好的選擇。產品豐富，兼容性好，體驗也不錯。N-Trig被封為微軟“御用”之后，產品選擇也只有了Surface系列。Apple Pencil也只有iPad Pro一條選擇。目前市面上的平板，如果是搭載Wacom筆的，一般有電池的，就是采用了Wacom AES技術的。畢竟對于大多數都廠商來說，對于手寫筆的參數并不會標記那么清楚。
對于學生這個龐大的群體來說，有一支筆，真的非常方便。同時，參加會議的時候也能夠很方便做筆記（配合OneNote還能錄制音頻）。所以，在2016年的新年，不考慮試一試么？
延伸閱讀
Wacom vs N-Trig - A Modern Comparison
WARNING: This post is long. I wrote this because I could not find an unbiased comparison of the?modern?N-Trig and Wacom technologies online. It was written in response to the artistic outcry regarding the Surface Pro 3. If you are an artist, I believe it is worth reading.UPDATED as of 20th June 2014 to reflect N-Trig software advancements.
UPDATED as of 23rd June 2014 to reflect new direct Digitizer comparison information.
Those of you who may visit this site regularly will know that I am a game developer, but what you might not know is that I also do a lot of sketching. (Maybe one day I will post the stuff online)
Since I am a geek, I do almost all of my sketching digitally, which means I am always looking out for new developments in digitizer technology. This brings me to this post in particular:
Following the announcement of the?Surface Pro 3, many artists were shocked and disappointed by the news that the SP3 would be using?N-Trig?technology rather than?Wacom?technology like the SP2. This is a perfectly understandable reaction, considering how the two have compared historically. A year ago, this news would have marked a fatal deal breaker in the eyes of all artists (including myself).
However, as someone who has used both the?newest?Wacom technology and the?newest?N-Trig technology on various tablets, I can tell you that the gap between these two brands is not as large as many still think.
This is a direct comparison post, between the most recent N-Trig digitizers and the most recent Wacom digitizers. I will compare the two technologies based on their practical performance. Both in terms of software and hardware. However, I will not compare the two on details like price. Wacom digitizers are significantly more expensive, but since that this does not ultimately effect the?drawing experience,?it is not relevant in the context of this comparison. I also neglect device specific factors like extra buttons and other details like N-Trig AAAA battery requirement for the same reason, this is a pure?digitizer comparison.
Pressure Sensitivity
N-Trig devices have?256 Levels?of pressure, while Wacom devices can range from?512?all the way up to?2048. As far as numbers go, its is clear to see that in this regard Wacom devices are superior. However, it is important for us to understand what it means to have more levels of pressure.?Having more than 256 levels of pressure only makes a difference if you are working with brush that is above size 256.? In other words:
When drawing with a Hard Brush, at a Brush size that is lower than 256, there is no difference in?sensitivity?between Wacom?and N-Trig
This is an important concept for people to grasp, because most artists do not work with brush sizes above 256. Furthermore, the difference does not become easily perceptible for a little while after that.
Some professions will require large brushes. For example: someone who is working on a poster that is going to be blown up to billboard sizes (and aren't using vectors) will definitely need a tool with higher than 256 Levels of pressure.
[Begin Edit] Since this topic in particular is of great interest, I will expand further to ensure there is no confusion.
Imagine using a 100px brush with a device capable of 100 pressure levels, and pressing down with 40/100 levels of pressure, 40% pressure. Based on common software implementation, this will draw a 40px circle. Now imagine using that same brush on a device that has 100,000,000 pressure levels, you press down with 40,000,001/100,000,000 pressure levels, 40.000001% pressure. The circle drawn is still only 40px wide. In this instance, you only need 100 pressure levels to hit every possibility, any pressure levels in between are simply not used.
The pressure curve (mentioned after this edit), can be used to squash the useful range of pen. Lets use a contrived example, mapping all pressure to half of the available pressure levels. We are still in a position where a digitizer with 256 levels of pressure is no different up to brushes of size 128px, which is still larger than what is necessary for most work. Even in the extreme case where someone wastes half of their pressure range, 256 levels is enough.
There are also other factors involved other than just brush size, you can use pressure to vary things like Opacity, Values, Jitter, and a heap of other factors. The point of this pure brush-size example was to encourage this type of thinking across to board: many programs have whole-number opacity percentages, or HSB/RGB parameters that only have a range of 100, 256 or 360. In many of these cases, it still makes little (in the 360 case) or no difference at all to have a more sensitive piece of hardware.
Now, there?are?a few cases where the average artist may use a much larger brush, for example, its common to use a very large air-brush for much smaller areas to ensure neat coverage. So if your immediate thought is that you never ever use brushes larger than 256, you may want to think again.
Furthermore, there is another point which I have neglected to mention which ties into the physical limitations of humans. It is very difficult for a human to apply force in small quantities and, when dealing with pressure levels in the hundreds or thousands, the difference in force between each level ends up being incredibly minute. This means that precisely using all the pressure sensitivity of your device is not easy, and some might argue that its outside of physical human capabilities entirely.
In summary, digitizer companies use pressure levels in the same way that many tech companies use specs: they count on a lack of public understanding in order to justify expensive upgrades that are largely unnecessary. 256 vs 512 vs 1024 vs 2048 is, for the most part, just marketing.
[End Edit]
While the levels of pressure do not make difference to most artists, there are some other factors that do. The most important two are:?The Pressure Curve?and?IAF - Initial Activation Force.
In mathematical terms: the Pressure curve is a function which translates your physical pressure (pounds of force) into virtual pressure. A steep pressure curve will mean that small modifications in your physical force will have drastic effects on the line that appears on screen.
The default pressure curve on Wacom devices is often described as more natural than the N-Trig curve. Furthermore, Wacom devices allow modification of the pressure curve to suit individual needs while N-Trig has no easy method of modifying the default curve.
The other factor, IAF, is the amount of initial force required before marks begin to register. On Wacom devices this is very small, last I checked it was 1 gram of force. For N-Trig devices the IAF is noticeably larger, partially due to the default pressure curve. These two factors are what places Wacom above N-Trig in terms of pressure sensitivity.
Winner: Wacom
Stroke Accuracy
When it comes to drawing, nothing can be more invaluable than having your marks appear where you'd expect them to appear. This is Stroke Accuracy. When drawing with a Wacom device, you draw with respect to the hovering cursor, whether or not this aligns perfectly with your physical pen. This is something that you get used to over a short time.
On the other hand, modern N-Trig devices are very accurate (if not perfectly accurate) in this regard. The marks simply appear beneath the pen. For some, this is an invaluable experience. For others, working with the cursor in mind is satisfactory. In any case this is an area where Wacom needs to catch up.
Winner: N-Trig
Hover
Using either brand of digitizer, you can guide your cursor by hovering the pen close to the tablets surface. In the case of Wacom digitizers, this is important for you to line up your strokes. Hence, Wacom digitizers have a larger hover distance than N-Trig devices.
N-Trig devices also suffer from cursor lag when hovering. While your marks may always appear where the pen contacts the screen, the cursor may trail behind when it comes to hovering. Many artists who are not accustomed to this find it disorienting. For these reasons, the Wacom hover experience is superior.
Winner: Wacom
Stroke Delay
The stroke delay is the time is takes from the moment you finish physically applying the pen to the screen to the moment the mark finishes being drawn. In this instance, your mileage will vary significantly based on the device you are using. Since this largely depends on the underlying hardware, it is not easy to say which digitizer is superior.
Just for perspective:?My development machine at the time of writing is a Sandybridge 4GHz Hex-Core with 16GB of RAM and a HD6990. I have used a Wacom Cintiq 13HD on this machine, and still saw stroke delay when working with various brush sizes. On the other hand, I have a Galaxy Note 12.2, which is built with Wacom technology and I have not seen very much Stroke Delay at all. On the N-Trig side of things, I only have experience with modern N-Trig Laptops such as the Vaio Duo 13, working in Clip Studio Paint I did not notice any Stoke Delay when working with brushes at reasonable sizes.
The following is no longer true, see below for more information:
Once the N-Trig-based Surface Pro 3 is out, I will directly compare it to the Wacom-based Surface Pro 2. This comparison will not be entirely fair since the SP3 is "10-20% faster", but it is as close as we can get right now. Because I do not have enough data for a meaningful answer at this moment, I will neglect to give one.
[UPDATE - 23rd June 2014]
With the release of the N-Trig Surface Pro 3, a direct comparison between it and the Wacom Surface Pro 2 can be performed.?AnandTech, a tech review site has compared the pens?in terms of latency, yielding a ~30ms improvement on the side of the Surface Pro 3.
| Surface Pro 3 vs Surface Pro 2 pen latency - Table taken from?AnandTech |
Winner: N-Trig
Parallax
Parallax is the perceived misalignment of the pen tip and the drawn mark as a result of the physical distance between the pen tip and the pixels of the screen.
If you have a tablet and you don't know what I mean: take it out, open up a fresh drawing and press the pen to the middle of the screen and move your head. If you are using most Wacom devices, the mark will no longer be aligned with pen in the way you thought it was. This means that, if you move your head while drawing, pen marks will start being placed in locations that you do not expect.
Some Wacom devices, such as the Note 12.2, do not have parallax issues as pronounced as, for example, the Cintiq line. But all Wacom devices suffer from parallax to some degree. On the other hand, N-Trig devices do not have this issue because their digitizer technology is very thin. For this reason, N-Trig is the clear winner here.
Winner: N-Trig
Drift & Calibration
It is well known that Wacom devices suffer from drift. Causing cursor alignment issues at the edges and corners of the screen. Since most software is designed so that toolbars and buttons are at the edges and corners, this can be a very irritating issue.
Wacom devices will require regular re-calibration to improve accuracy. However, this cannot fix the edge and corner drift issues, since they are a hardware limitation.
On the other hand, N-Trig devices do not require re-calibration and are equally accurate at all locations on screen. For this reason, N-Trig wins this catagory.
Winner: N-Trig
Software
Software is a big deal for everyone using these devices, after all, it doesn't matter if one seems better than the other if they don't work with your favorite programs. In this regard, N-Trig has made significant strides towards ensuring compatibility across key programs.
The following is no longer true, see below for more information:
However, N-Trig is still not perfect in this regard. There are still a few programs which do not function correctly with N-Trig devices due to the industries historical dependence on Wacom and the Win-Tab driver. N-Trig have released a 64-Bit compatibility driver for Win-Tab, but this means that 32-Bit Win-Tab software will not work correctly unless it was built with the Ink API.
To expand on this point, this means that programs like Photoshop and Clip studio paint will work fine, but ZBrush for example will not. Which means that, if you are a 3D Sculptor, you simply cannot use a N-Trig device for your work.
N-Trig will likely pick up support for more software as time goes by, either the software will be updated to a 64-Bit version or support will be added directly. In any case, at this very moment it is still a problem for 3D artists everywhere. For this reason, Wacom is superior in this category.?
[UPDATE - 20th June 2014]
With the launch of new WinTab drivers coinciding with the release of the Surface Pro 3, all modern N-Trig digitizers can boast compatibility with Wintab software across the board. This includes, ZBrush, Corel Painter, Krita, Paint Tool Sai etc. In addition, more and more art software is being built using the generic tablet pc ink api, meaning that not only can you can use almost all legacy software, and will likely be able to use all future software with an N-Trig solution.
Furthermore, Wacom has a history of driver issues. These are, at best, minor annoyances and, at worst, can cause their products to become unusable for short periods of time due to loss of pressure or total unresponsiveness. In most cases, its not a deal-breaker for these issues to occur and the more severe problems occur very infrequently. However, driver bugs are just something people have grown to accept about the Wacom experience. Things like bugs and isolated issues should not have weight in this comparison, but these are not uncommon occurrences. Almost all Wacom tablet users will complain about driver issues at one point or another.
At this point, it seems inevitable to say that N-Trig wins this category, but there is one final factor that we have yet to discuss. Software built with wintab is optimized for wintab. This means that you are likely to experience (very slightly) reduced performance in software that added support for other devices later. While this is not as irritating as Wacom driver issues, it is still a consideration because it is a constant. I.e. While you may be able to find a fix for your driver issues, the same can't be said for the optimization of software. Digitizer users are at the mercy of software developers in this regard, and will be for a while.
Winner: Draw
Summary
Pressure -?Wacom
Accuracy -?N-Trig
Hover -?Wacom
Delay -?Draw?N-Trig
Parallax -?N-Trig
Drift & Calibration -?N-Trig
Software -?Wacom??Draw
As you can see, the distinction between the two is not so clear cut. Ultimately, your decision will depend largely on your preferences. If it is invaluable to you that your marks simply appear below your pen, then you may want to consider an N-Trig solution. If you are a dealing with mega resolutions you will want a Wacom device.?If you are irritated by Calibration or tend to switch tools often, N-Trig.
It is clear to me that the N-Trig vs Wacom debate is often driven more by historical prejudice than unbiased comparison. In my opinion, it is important for people to select tools based on merit rather than bias. Personally I am going to wait an see how the Surface Pro 3s digitizer holds up before deciding that it's the end of the universe.
總結
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