视觉特效合成概述An Introduction to Visual Effects Compositing

简介Overview

什么是视觉特效合成？合成是将两张或更多图像组合成全新图像的过程。但这不只是拼合图像——你还能合成视频片段、动画、文字、遮罩、粒子和图形等多种元素。这些元素有时被称为层（layers），因为它们彼此叠加，最终生成新的图像。What Is Visual Effects Compositing? Compositing is the process of combining two or more images to make a unique, new image. But it's not just about combining images. You can composite many different elements, such as video clips, animations, text, mattes, particles, and graphics. Sometimes these elements are called layers because they are layered on top of each other to produce the new image.

视觉特效涵盖的工作非常广泛，与调色和音频后期一样，是电影创作中充满创造力的一环。根据项目类型，你可能需要掌握其中部分或全部技能。中小型项目通常要求你独立完成整个镜头的制作，而大型工作室则会有专人负责 rotoscoping、3D、粒子、灯光等不同环节。Many tasks fall under the umbrella of visual effects. Just as with color and audio post-production, visual effects are a huge and exciting part of the creative filmmaking process. Depending on the type of work you do, you may need to learn some or all of the skills needed to create a finished visual effects shot. Smaller productions often require you to build shots from start to finish, whereas larger studios may have specialized artists dedicated to tasks such as rotoscoping, 3D, particles, lighting, and so on.

即使你以剪辑师或调色师身份受聘，也常常会被要求制作小特效。和所有后期工作一样，工具和技巧都需要反复练习；而理解工具背后的技术原理，能显著提升你解决问题的能力与效率。Even when you are hired as an editor or a colorist, you will often be asked to produce smaller effects. Like all aspects of post-production, learning the tools and techniques requires practice. Understanding the technology behind the tools will improve your problem-solving skills and efficiency.

随着行业交付周期越来越短，能够快速且高效地完成镜头制作的剪辑师和调色师尤为抢手。掌握 DaVinci Resolve 中 Fusion 视觉特效的基础，再加上调色和音频后期，会让你更具竞争力，也带来更多工作机会。As industry deadlines tend to grow shorter, editors and colorists who know how to finish shots quickly and efficiently are in the highest demand. Learning the basics of Fusion visual effects in DaVinci Resolve—along with color correction and audio post-production—will make you a more valuable artist and open up more job opportunities.

视觉特效不再是大片专属Getting Started with Visual Effects

视觉特效曾是大预算电影的专属。而借助内置于 DaVinci Resolve 的 Fusion，即使预算有限，你也能为任何节目加上电影级的视觉特效。Visual effects were once a luxury reserved only for big-budget feature films. With the power of Fusion built into DaVinci Resolve, you can add feature film–quality visual effects to any program without a massive budget.

如果你以为视觉特效只关乎外星人、飞船和爆炸，那就错过了大量能让任何项目更出彩的小特效。事实上，大多数视觉特效其实是修正类效果、画面清理，或是天空替换、窗户替换这类不易察觉的隐效。这些特效制作时间不长，却能从构图不佳的 B-Roll 到灰蒙蒙的天空，全方位提升成片质量。If you think visual effects are only about creating aliens, spaceships, and explosions, you are missing out on the many smaller effects that can improve any project. In fact, most visual effects consist of corrective effects, clean-up work, or inserting subtle hidden effects such as sky and window replacements. These effects don't take long to do and can improve everything from poorly framed B-Roll to dull gray skies.

添加元素Adding Elements

天气难以预料，剧本要下雪，你就得做出雪来！因此，制作雪、雨、雾甚至闪电等元素，是视觉特效师的核心技能。Fusion 的粒子系统能生成自然飘落、移动、飘散的逼真天气元素。Weather is unpredictable, and when the story calls for snow, you need snow! That's why creating elements such as snow, rain, fog, and even lightning are essential skills of the visual effects artist. You can use the particle system in Fusion to create realistic weather elements that move, fall, and drift naturally.

有些内容在实景拍摄中实在太危险。例如烟雾、飞溅的碎片和火焰，在演员和整个剧组在场时始终存在风险。这些元素通常可以单独拍摄，后期再用合成的方式加入，既安全又能达到真实效果。Sometimes it's just too dangerous to do things on a real set. For example, smoke, flying debris, and fire are always dangerous when actors and an entire crew are involved. In many cases, these elements can be shot separately, and you can composite them in later as a safer yet realistic-looking alternative.

动物与儿童Animals and Kids

动物和儿童的表现难以预判，会让每一天的拍摄都拖到极限。解决方法是拆分镜头——把动物和主体动作分开拍摄，这样既能保证按时完成，又能避免延误进度。通过无缝合成，你可以把画面的不同部分组合在一起，做出像一镜到底的 split-screen 合成效果。The unpredictable nature of working with animals and children can slow each shooting day to a crawl. Being able to divide and conquer a shot by splitting it up and shooting animals separately from main action can ensure that you get the shot completed without schedule overruns. Through seamless compositing, you can combine each section of a frame to create a realistic split-screen composite that looks like one take.

天空替换Sky Replacement

完美的日落或点缀蓬松云朵的蔚蓝天空，是任何场景的理想背景，但天气却不受你控制。当全组就位、设备已经租好、时间在倒数，即使天气不配合也得继续拍。这时就轮到（极其常见的）天空替换技术登场了。Fusion 的 keyer、rotoscoping 工具、tracking 与 3D 合成可以去除灰暗的天空，或挽救过曝的天空。再配合 Fast Noise 或体积特效，就能让原本晴朗的天空多出几朵戏剧性的云彩，即便拍摄时并不存在。A perfect sunset or a bright blue sky with puffy clouds are great backdrops for any scene, but weather is out of your control. When everyone is on set, the equipment is rented, and the clock is ticking, you've got to get the shot even when the weather isn't cooperating. That's where the (extremely common) art of sky replacement comes in. Fusion's keyers, rotoscoping tools, tracking, and 3D compositing can remove ugly gray skies or salvage overexposed skies. Add in some Fast Noise or volumetric effects and that clear blue sky can include beautiful dramatic clouds that weren't there during the shoot.

借助 Fusion 的 3D 控制，你还能模拟光线方向、大气雾霭和真实的视差镜头运动——这些都是区分可信的天空替换和廉价假效果的关键。With the 3D controls in Fusion, you also can simulate the light direction, atmospheric haze, and realistic parallax camera movement—all elements that can make the difference between a believable sky replacement and a cheap, artificial fake.

表演与外观修正Performance and Cosmetic Fixes

修正或改善演员不够完美的表演，可以省去昂贵的补拍。这类合成任务观众几乎察觉不到，操作也往往很简单，具体取决于修正内容。比如，拍摄时经常被忽略、放映时却格外刺眼的细节是：演尸体的演员眼睛不自觉地动了。把某一帧闭合的眼睛合成到整个镜头上，是一项能救场并复用于类似修复的技能。去除疤痕、纹身或不均匀的晒痕也使用类似技术，可借助 Fusion 的 planar tracker、paint 工具和 rotoscoping 完成。Correcting or improving an actor's not-quite-perfect performance can avoid the need for expensive reshoots. This common compositing task is rarely noticed by an audience and can be simple to do, depending on the required fix. For instance, a detail often missed during shooting (but painfully obvious in the screening room) is when an actor portraying a dead body involuntarily moves his eyes. Compositing closed eyes from one frame over an entire shot is a skill that can save the shot and be repurposed for many similar fixes. The removal of scars, tattoos, or uneven tan lines all use similar techniques and can be performed using Fusion's planar tracker, paint tools, and rotoscoping.

更换场景Changing Locations

制作预算总是限制着你能在哪里、什么时候拍摄，但简单的环境修饰就能掩盖这些限制，彻底改变整个场景的氛围。这类效果可以包括在行驶的车内替换窗外画面——因为你不可能封锁时代广场来拍摄；也可以是把负担得起的底层公寓"挪"到带顶层豪华视野的视角。这些是视觉特效师的常见任务，对剪辑师和调色师来说也是能快速完成的小修小补。Production budgets always limit where and when you can shoot a scene, but simple environmental enhancements can disguise those limits and change the feel of an entire scene. Such effects can consist of replacing windows in a moving car because you couldn't close Times Square to shoot your scene, or "moving" the ground-floor apartment location you could afford to a penthouse view. These are common tasks for the visual effects artist and can be very quick fixes for editors and colorists to perform.

擦除威亚Wire Removal

视觉特效也用于为已经危险的特技增添真实感。让演员借助爆炸冲击或超自然力量飞越画面时，通常需要安全吊带和威亚装置。你可以用 Fusion 的简单克隆（clone）工具和跟踪（tracking）来隐藏这些威亚和吊带——当视觉特效师忙于大型合成时，剪辑师和调色师可以临时接手这类工作。此外，在 Fusion 中练就的擦除威亚技能同样适用于移除灯架、电话线以及碍眼的天线。Visual effects are also used to add realism to already dangerous stunts. Getting performers to fly across the screen from either explosive force or supernatural powers often requires safety harnesses and wire rigs. You can hide those rigs and wires using Fusion's simple clone tools and tracking, a task that editors and colorists can take on in a pinch when the visual effects artists are busy with larger composites. Plus, the wire removal skills you use in Fusion techniques can also apply to removing lighting stands, telephone wires, and unsightly antennas.

扩展场景Set Extensions

你可以把环境修饰提升一个层级，打造完整的扩展场景（set extension），让观众在视觉上被"运送"到指定地点（同时让你的剧组安全地待在摄影棚里）。与其把全体演职人员拉到喜马拉雅山麓，不如把镜头的背景替换为寺庙、雪山。使用 Fusion页面在后期跟踪镜头运动，替换绿幕（green screen）为场景的 3D 扩展即可完成。对于年代剧或科幻片，这类效果能节省大量时间和金钱，因为你不必搭建巨型布景，只需在演员周围搭建局部布景并铺设绿幕。You can take environment enhancements to the next level to create entire set extensions that visually transport your audience to a specific location (while keeping your production safe at home on a sound stage). Instead of shipping the whole cast and crew to the Himalayan foothills, you can replace the background of your shots with temples and mountains and snow. For period pieces or science fiction, such effects can save enormous amounts of time and money because you don't have to build massive sets. You just construct set fragments around your actors and place green screens in the surroundings. Using the Fusion page during post-production, you can track the camera movement and replace the greenscreen with 3D extensions to your set.

动态图形Motion Graphics

动态图形（Motion Graphics），也叫动态设计（Motion Design），核心是为图形元素添加动画。它是视觉特效、动画和图形设计的融合，目的是在屏幕上呈现信息。由于信息传递是核心目标，文字在几乎所有动态设计项目里都扮演主要角色。Fusion页面同时提供 2D 和 3D 文字工具，还有创意绘图、Bézier（贝塞尔）形状绘制工具，以及深度可调的样条（spline）动画控制，让你能够创作出能传达信息、教学、娱乐的精彩动画设计。Motion graphics, or motion design, is all about animating graphic elements. It's the marriage of visual effects, animation, and graphic design with the goal of presenting onscreen information. Because information in some form is the objective, text often plays a primary role in almost every motion design project. The Fusion page includes both 2D and 3D typography tools along with creative paint, Bézier-shape drawing tools, and incredibly deep spline animation controls. They enable you to create engaging animated designs that communicate, educate, and entertain.

学会观察Learning to See

如果想做出高质量的视觉特效，就必须对身边世界的呈现方式保持高度敏感。视觉特效必须看起来、感觉上都真实可信，否则观众会立刻出戏。这种细致入微地观察周围世界的能力，与掌握视觉特效的技术和艺术层面同等重要。If you want to create high-quality visual effects, you need to be very conscious of how the world appears around you. Visual effects must look and feel real, or your audience will stop believing. The skill to observe the surrounding world in painstaking detail is just as important as mastering the technical and artistic side of visual effects.

要成为技艺精湛的视觉特效师，你必须开始留意真实世界中的光线、透视和深度呈现方式，并把这些观察融入合成作品里。To become a skillful visual effects artist, you must start noticing how light, perspective, and depth appear in the real world, and then bring those observations into your composites.

如果合成中的所有元素都本应处在同一场景里，就必须保证它们的光照方向一致。把相对尺寸、视差运动（parallax motion）和深度模拟到真实世界级别的精度，是特效镜头真实感的根本所在。If all the elements that make up a composite are meant to be in the same location, then you must make sure that light hits them all from the same direction. Simulating relative sizes, parallax motion, and depth to a real-world level of detail is essential to the realism of an effects shot.

开始做视觉特效时，从小处着手。Fusion页面功能极其深广。Fusion 内嵌于 DaVinci Resolve 的好处在于，只需一键就能进入合成：先动手试试能不能做出效果，然后根据你的技能和可用时间，要么交给视觉特效师继续处理，要么自己完成。As you begin creating visual effects, start small. The Fusion page is very deep and incredibly powerful. The beauty of having Fusion built into DaVinci Resolve is that you can jump into creating visual effects with one click; try something out to see if it will work, and then, depending on your skill and the time available, either pass it off to your visual effects artists or finish it yourself.

视觉特效合成依赖多种工具的组合，而不是任何单一的滤镜效果。做好它需要时间、耐心和经验，但这是一件极其令人兴奋的事，可以通过不断实验和练习来掌握。最终，你将创造出想象中最激动人心的电影时刻。Visual effects compositing is about a combination of tools rather than any single filter effect. It takes time, patience, and experience to do well, but it's an incredibly exciting activity that you can learn through experimentation and practice. Eventually, you'll create the most thrilling cinematic moments imaginable.

正如沃尔特·迪士尼所说："做不可能的事，是一件有趣的事。"As Walt Disney said, "It's kind of fun to do the impossible."