Non-photorealistic rendering(非真實感渲染)_印象派畫風效果_卡通化_ex1

非真實感繪製（Non-photorealistic rendering，NPR）

是電腦圖形學的一類，主要模擬藝術式的繪製風格，也用於發展新繪製風格。和傳統的追求真實感的電腦圖形學不同，NPR受到油畫、素描、技術圖紙，和動畫卡通的影響。NPR已經以「卡通著色」的形式出現在電影和電子遊戲中，也出現在科學視覺化、建築插圖和試驗動畫中。這個方法在現代實用的例子是卡通動畫（Cel-shaded animation）。

改自wiki

標準著色（左）vs   NPR著色（使用卡通著色）（右）

卡通渲染（Catoon Rendering / Toon Shading / Cel Shading）
是NPR(Non-PhotoRealistic)技術中的一種。

screenshot from "A Scanner Darkly" 2006
- The process for animating this film after shooting, was by "Rotoscoping" each frame, and then applying cel-shading filters to the footage. The rotoscoping allowed for animators to further enhance gestures or facial expressions captured during shooting, and also made applying the cell-shading filters to the vectors (captured by the rotoscoping) more accurate.

Patent drawing for Fleischer's original rotoscope.

 The artist is drawing on a transparent easel, onto which the movie projector at the right is beaming an image of a single movie frame.
專利圖紙為弗萊舍的原始rotoscope。
藝術家在透明畫架，其上右邊的電影放映機喜氣洋洋一部電影幀的圖像繪製。







Rotoscoping   對位

Rotoscoping is an animation technique in which animators trace over footage, frame by frame, for use in live-action and animated movies. Originally, recorded live-action movie images were projected onto a frosted glass panel and re-drawn by an animator. This projection equipment is referred to as a rotoscope. Although this device was eventually replaced by computers, the process is still referred to as rotoscoping.


animators 動畫師
trace over 描繪(出)
footage 鏡頭
live-action ------> Live-action animated film  

A live-action animated film is a film genre which utilizes various traditional animation or computer animation sequences, usually blended together, in live action films.
真人動畫電影是一個膠卷/影片類型，
它利用各種傳統的動畫或電腦動畫序列，通常混合在一起，在真人電影。

frosted 磨砂
re-drawn 重繪
 is referred to as 被稱作








Cel shading is a flat looking 3D image, with a cartoonish look exemplified by animated movies.

The basic elements of a cel shaded effect are :
Sharp shadows
Little or no highlight   /  不以強光照射
Outline around objects  /  邊界 



 以下我們來看一下一個簡單的事例

Cel Shaded - Digital rotoscoping filter








The input of a two-dimensional NPR system is most commonly an image; however, there are systems that take 3D geometry information as input and produce a 2D image or video as as output. Again, many of the systems are intended to mimic a desired artistic style, such as watercolor, impressionism, or pen and ink drawing. Sketchy style is a rendering form that mimic hand-drawn graph primitive.

mimic (vt): 模仿；模擬
desired artistic style : 所需的藝術風格
impressionism : 印象派
hand-drawn : 手繪
graph primitive : 原始圖

卡通渲染是一種非真實感渲染（non-photorealistic render）。
而卡通著色是一種簡單非真實著色。
它運用很少的顏色通常是顏色調和，所以經常是從一種色調變化到另一種色調，
但是給人一種三維模型的感覺。




參考文獻部落格網址

Live-action animated film

link: https://en.wikipedia.org/wiki/Live-action_animated_film


卡通渲染 (Toon Shading)

link :
https://cg2010studio.wordpress.com/2011/07/10/%E5%8D%A1%E9%80%9A%E6%B8%B2%E6%9F%93-toon-shading/?iframe=true&preview=true


History Of The Rotoscoping Technique

link :
http://www.brattleblog.brattlefilm.org/2015/09/11/history-of-the-rotoscoping-technique-2-3231/#.V17jsih97IU