Cel-shading in Art and How to Use It

by Laura C. Jones
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If you are a fan of video games or animation films, you must have noticed that the images appear unique and hand-drawn. This type of art is referred to as cel-shading. The style is considered unique because it is very challenging to accomplish with 3D rendering. This article talks about cel-shading in art and how it is used.

What Is Cel-shading?

Also referred to as cell shading or toon shading, cel-shading is a unique type of non-photorealistic rendering meant to add an element of evenness to your 3D computer graphics. This style involves the use of less shading color as opposed to a shade gradient or tint and shades. Cel-shading is normally used to mimic the style of comic books and cartoons.

It is also used to give the render a typical paper-like texture. Once the shape has been flattened, it pops, making the cartoons and animation images look unique. The main idea of cel-shading is to shade and highlight the shapes with chunky, simplified colors instead of the subtle gradients that are normally seen in real life.

Origin of Cel-shading

The name cel-shading comes from cels (the short for celluloid). These are clear sheets of acetate that were used in traditional 2D animation. Although it has been in use for many years, this style of art became common in the early 2000s. The first video game to incorporate real-time cel-shaded visuals was Jet Set Radio for the Dreamcast, which was released in 2000.

This game gained a lot of attention from the media for its unique graphic style. However, this style was first unveiled in Japan at the Tokyo Game Show in 1999 by Sega — a popular Japanese multinational video game developer and publisher based in Shinagawa, Tokyo.

After its release, the video game went on to win three prestigious gamin awards: E3 Gamer Critics Award for the best console game in 2000, a Gamer Developers Choice Award for excellence in visual arts and game innovation spotlights in 2001, and Annual Interactive Achievement Award in 2001.

This video game was such a success that even the upcoming game developers started using the cel-shading style in their games. Many veteran game developers also implemented this style for their long-running franchises. For example, the developers of Bomberman and Harvest Moon applied the cel-shading technique throughout the series.

A Jet Set Radio sequel titled Jet Set Radio Future, which was released in 2002 also applied cel-shading. This sequel, together with Sly Cooper and the Thievius Raccoonus, was created to moderate the success of the original game.

From this point, the cel-shading technique became even more widespread, featuring in many other titles for multiple systems, including Cel Damage, Dark Chronicle, Viewtiful Joe series, and XIII.

But despite the widespread acceptance of the cel-shading style, these games didn’t sell as many copies as you would have expected. Sales remained low for several years until Nintendo decided to incorporate this visual technique into one of its longest-running franchises. The year 2005 saw the highest number of games with this visual style released within one year.

At this time, game developers had already realized that licensed games could be produced in this style since most games were based on cartoons. So, cel-shading was the best way to create games based on cartoons.

Most of the games released in 2005 in this visual style garnered a lot of critical and commercial success. But the most successful game released that year was the Dragon Quest franchise, which remains one of the most successful games in Japan.

How Do You Do Cel-shading?

The basic cel-shading process starts with a normal 3D model. The only difference between cel-shading and conventional rendering is the non-photorealistic illumination model. In cel-shading, conventional flat lighting values are estimated for each pixel and then quantized to a smaller number of distinct shades to generate the unique flat look, where the shades and highlights appear as chunks of color instead of being evenly mixed in a gradient.

Outlines

Wireframe Technique

You can create black ink outlines and contour lines with a variety of techniques. For example, you can start by rendering a black outline that is slightly greater than the shape itself. Then, cull the back-face and draw the back-facing triangles in black. You can use a wireframe several times with altered translation to draw the back-faces for the dilated silhouette.

Alternatively, you can render the back-faces while solid-filled in a vertex shader, with their vertices translated along the vertex normals. Once you have created the outline, you should set the back-face culling back to normal to create the shading and voluntary textures of the outline. Since the back-faces always sit deeper in the scene than front-faces, you need to composite the image through Z-buffering.

A final result is an object outlined with a black sketch and inner contour lines. Cel shading commonly refers to the use of this outlining technique in animation and games, though initially, this term referred to the flat shading method, whether the outline was applied or not.

Edge-Detection Technique

This technique is mainly used in 2D image processing and outlining. With this method, you start by rendering the scene with cel-shading to a screen-sized color texture. Then, you render the depth-information of the scene to a screen-sized texture. Even the world-space surface normals must be rendered as a screen-sized texture.

Then, apply an edge-detection filter to the normal and depth surfaces to create an edge surface. Make sure the texels on the detected edges are black and the rest white. Lastly, composite the edge and color surfaces to generate the final rendered image.

Cel Shading Games

The list of video games that use the cel-shading technique is endless. Here are just some of the most popular ones.

Afro Samurai

This action video game was adapted from the popular Japanese manga and anime series of the same name. It was developed in 2008 by Namco Bandai Games for PlayStation 3 and Xbox 360. The game uses cel-shading elaborately, making the images appear more detailed to the point of looking like illustrations.

Battlefield Heroes

Battlefield Heroes is a third-person shooter video game created by EA DICE in 2009. It was further advanced by Easy Studios and published by Electronic Arts for Microsoft Windows.

This game was considered less demanding on computers than the previous games of the series. This third-person game features many cel-shaded cartoon graphics. Its cel-shaded characters are categorized into different class types with various outfits and accessories.

Call of Duty: Black Ops 4

This is a multiplayer first-person shooter was developed in 2018 by Treyarch and published by Activision. It was released globally in October 2018 for Microsoft Windows, PlayStation 4, and Xbox One. This game features thick black cel-shaded outlines that make everything, including Hydro Dam and Nuketown Island pop with more color.

Cel Shading Animes

The dozens of useful anime drawing tutorials have made the process of creating anime characters easier and funnier. Cel shading has become one of the most common styles of creating animations. This technique mimics traditional animation, which applied simple shading without mixing the colors to make the process of animation easier.

To enhance the cel-shading technique, there are several tools you can use, including gradients, effects, and filters. These tools will help you to give your image the right atmosphere and feeling. Since this style is very noticeable, it can be used in animation as well as illustration. This style has been used in a couple of popular animation films. Here are some of the most popular cel-shaded anime films.

Appleseed (2004)

Appleseed is a popular Japanese animated post-apocalyptic action film produced and directed by Shinji Aramaki. This film, which was released in 2004, was adapted from the Appleseed manga by Masamune Shirow. It tells the story of a former soldier, Deunan Knute, who is on a mission to find data that can restore the reproductive abilities of bioroids – a group of genetically engineered clones. The cel-shading technique used in this film gives it a cartoony appearance and makes it look amazing on less powerful devices.

Futurama

Futurama is a science-fiction animated sitcom produced by Matt Groening. This American film first aired on Fox in March 1999 and later on Comedy Central in March 2008. It tells the story of Philip J. Fry, who is revived in the 31st century after being preserved cryogenically for 1000 years. This film uses cel-shading for the 3D scenes and spaceships. It employs an innovative combination of hand-drawn 2D art, digital color, and 3D computer animation.

Family Guy (2012)

Family Guy is a popular American animated TV series produced by Seth MacFarlane and David Zuckerman. It first aired on Fox in January 1999. The film centers around the Griffins, a family consisting of two parents, three children, and an anthropomorphic pet dog.

The show displays much of its wit in the form of metafictional cutaway jokes that often ridicule the American culture. It employs the cel-shading CG style for different scenes, especially the ones that involve cars and moving backgrounds.

In Summary

Now that you know what cel-shading is and how to use it in your artwork, use it to add a more artistic and fantastic element to your video games and animation films. Thankfully, this visual style is more cost-effective than the traditional 2D animation techniques.


Featured image source: Pinterest

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