Chapter 2: Foundations of Expression

Overview

This chapter explores the relationship between drawing and CG production, the basic properties of color and motion, and typography.

Book Structure

Chapter 1: CG Fundamentals
- Understanding the characteristics and history of CG, its applications in various industries, and the workflow.
Chapter 2: Foundations of Expression
- 2-1: Drawing
- 2-2: Color and Motion
- 2-3: Typography
Chapter 3: 2D CG and Photography
- Understanding the basics of 2D CG, digital camera photography, and retouching.
Chapter 4: 3D CG Production
- Understanding the production methods for 3D CG video works.
Chapter 5: Technical Foundations
- Understanding the hardware and software for CG production, and the basics of digital data.
Chapter 6: Intellectual Property Rights
- Understanding copyright among intellectual property rights.

2-1: Drawing

Drawing is fundamental to painting and effective as a training method for enhancing observational skills.
It involves accurately capturing the shape of a motif and expressing three-dimensional depth through shading.
In CG production, drawing skills are valuable for understanding the structure of the drawing target, composition, perspective for expressing depth, light direction, and gradation expression.
Leonardo da Vinci's Drawing “Leda's Head”: Cultivating observational and expressive skills through drawing can be widely applied in CG production.
Two-Point Perspective Interior: Perspective is a technique for expressing depth in paintings, with vanishing points (VP) where lines converge to represent depth and distance. Two-point perspective has two VPs on either side.

2-1-1: Drawing and CG

Generally, drawing refers to a study that accurately depicts the shape of a motif through monochrome line drawings and shading using materials such as pencils or charcoal.
It can also refer to sketches drawn to develop ideas in the process of creating a work (Figure 2.1).
In any case, drawing mainly uses monochrome to objectively capture the shape in front of you or the image that comes to mind, and to depict the presence and shadows of the motif three-dimensionally and realistically.
It is important to carefully observe the motif and the surrounding space, understand the presence of things and the beauty of the shadows created by light, and express them.
The observational and expressive skills developed through drawing can be widely applied in CG production.
For example, understanding structure, composition, observing and expressing light and shadows, and knowledge of perspective enhance modeling sense and give CG a sense of realism.
Figure 2.1: Examples of Excellent Drawings
- [a] Leonardo da Vinci's drawing "Head of Leda"
- [b] Michelangelo's drawing "Three Standing Men"
Although drawing is not a self-contained work, it is natural that an excellent drawing has high value as an expression work that goes beyond the meaning of a mere study or sketch.

2-1-2: Perspective

Perspective is a technique for expressing perspective in paintings, and typical examples include perspective drawing (perspective method/linear perspective) and aerial perspective.
Perspective is also called perspective or simply perspective.

[1] Perspective Drawing

To accurately capture and draw shapes in drawing, use the principle of perspective.
Figure 2.2 shows the scenery when standing on a railway track and looking far away.
Although the actual rails extend parallel forever, the rails converge toward the horizon and appear to intersect there.
This intersection is called the vanishing point (VP)1, and the height of the eye is called EL2.
The height of the eye (EL) is the horizon (horizontal line) at the position of the eye when the observer looks straight ahead.
Lines converging to one point on the EL represent depth and distance, and the technique of using line convergence to create depth is linear perspective.
- *1 Abbreviation for Vanishing Point.
- *2 Eye Level abbreviation.
One-point perspective is a perspective method with only one VP.
As shown in Figure 2.3, when the observer stands with his back to the wall of the room, extending the parallel lines such as the boundaries between the ceiling and the wall and the floor and the wall from that position will cause these lines to converge to one point on the other side of the room.
Two-point perspective is a perspective method in which two VPs are created on the left and right.
Figure 2.4 is a diagram of a corner viewed from the outside of the room (through the room), with two VPs on the left and right.
If you look at the motif diagonally from the same level as the ground, that is, the height of the eye (EL), it will be a two-point perspective, but if you look up or down, there will be three VPs, so you will draw with a three-point perspective (Figure 2.5).
The expression of perspective using perspective drawing changes depending on the relative position of the viewpoint (observer) with respect to the object, the distance to the object, the height of the viewpoint, and the direction of the line of sight.
The expression ``perspective (or perspective) is distorted'' is often used to describe a state where the perspective is incorrect, but understanding perspective allows you to correct the perspective.

[2] Aerial Perspective

Aerial perspective is a technique that uses the properties of the atmosphere to express perspective.
We know from experience that things that are far away appear paler and hazier.
At this time, the color contrast does not decrease overall, but the blue tint remains even when it is far away.
For this reason, when you see a landscape with mountains overlapping in the depth direction, the farther away the mountains are, the lighter and more blue they appear.
This phenomenon can be explained by the fact that molecules in the air scatter blue light better than red light.
Just like the sky is blue on a sunny day, distant objects also appear bluish because the blue component is strong.
Aerial perspective is an application of this principle, and perspective can be expressed by making the colors paler and more blue the farther away they are.
Also, the details tend to be ambiguous the farther away they are (Figure 2.6).
Figure 2.2: Diagram of standing on a railway track and looking at the horizon
Figure 2.3: Interior seen with one-point perspective
Figure 2.4: Interior seen with two-point perspective
Figure 2.5: Interior seen with three-point perspective
Figure 2.6: Aerial perspective
- [a] Landscape photo where the principle of aerial perspective can be confirmed
- [b] Work expressing depth using aerial perspective

2-2: Color and Motion

In CG production, in addition to the physical characteristics of color and motion, it is also necessary to understand the characteristics of the human being who receives them.
Here, in addition to the basic characteristics of color and motion, we will also explain how humans understand them.

2-2-1: Color

When handling colors, it is essential to understand color expression methods using additive and subtractive color mixing, and to understand color attributes.
It is also necessary to consider human psychology.

[1] Primary Colors and Three Attributes

Mixing different colors results in another color, which is called color mixing.
Color mixing is mainly classified into additive color mixing and subtractive color mixing.
Additive color mixing is the mixing of colors when emitting light, such as with lighting or display monitors.
As you mix the colors (light), the brightness gradually increases and approaches white.
On the other hand, subtractive color mixing is the mixing of colored films or paints.
As the light absorption components increase each time a color material is layered, the color gradually becomes darker and approaches black as the colors are mixed.
In both additive and subtractive color mixing, most colors can be created from three colors, and this is called the three-color nature of colors.
Colors that cannot be created by color mixing are called the three primary colors, and most colors are created by mixing the three primary colors.
The three primary colors for additive color mixing are red (R), green (G), and blue (B) (Figure 2.7 [a]), and the three primary colors for subtractive color mixing are cyan (C), magenta (M), and yellow (Y) (same figure [b]).
Many printed materials and printers use black (K) in addition to these three primary colors.
Furthermore, colors have common attributes.
Colors have a certain hue, just as red and green have different hues.
Also, colors have a certain vividness, just as vivid red and gray-like red have different vividness.
And just as red and pink have similar hues but different brightnesses, colors also have a certain brightness.
Hue (hue), saturation (vividness), and value (brightness) are the three attributes of color (Figure 2.8).
Similar to RGB for additive color mixing and CMY (CMYK) for subtractive color mixing, it is also possible to express a specific color that can be created by combining them by specifying each component of HSV.
Figure 2.7: Color mixing using three primary colors
- [a] Additive color mixing
- [b] Subtractive color mixing
  *Note 3: In each diagram showing the three primary colors of additive and subtractive color mixing, the colors located diagonally across the center white and black are called complementary colors. Red and cyan, green and magenta, and blue and yellow are examples. When these complementary colors are mixed in certain amounts, they become achromatic colors (gray, white, black) without any hue.
Figure 2.8: Three Attributes of Color

[2] Color Scheme and Color Use

Visibility is an important aspect of color use.
A color is said to have high visibility when it can be easily detected even from a distance.
In general, black on a yellow background has high visibility, and this color scheme is used for warning signs at construction sites (Figure 2.9).
*Note 4: For example, when retouching a photo, the impression conveyed by the photo changes greatly depending on whether the overall color tone is made cool or warm. In video works as well, it is common to finely adjust the color tone for each scene to match the production intent.
Colors can be associated with special emotions or impressions, and the impression of temperature from color is one example.
For example, blue is associated with coolness and cold, and red is associated with warmth and heat, so they are called cool colors and warm colors, respectively.
Also, the impression of perspective may differ depending on the color.
For example, red may be felt to be closer than blue, so they are sometimes called advancing colors and receding colors, respectively.
Advancing colors are characterized by warm colors, high brightness, and high saturation, while receding colors are characterized by cool colors, low brightness, and low saturation (Figure 2.10).
Figure 2.9: Examples of highly visible color schemes
Figure 2.10: Examples of advancing and receding colors
- [a] Cat in the room
- [b] Cat in front of the door

2-2-2: Motion

Here, in addition to the principle that makes video works appear to move, we will also explain problems and tips to keep in mind when producing animations, especially among video works.

[1] Recognition of Movement

Even though the individual frames are still images, when they are shown in succession, they are felt to move like in the real world.
Video works such as movies and animations are created by applying these characteristics of human vision.
*Note 5: Frame rate refers to the number of frames (screens: frame) displayed per second, and the unit is fps (frame per second). A typical movie is 24fps.
In movies, 24 frames of still images per second are projected one after another on the screen.
Television broadcasts and video games have higher frame rates than movies, so they appear smoother, but on the other hand, even if there are only a few frames per second like in a flip book, you can still feel the movement to some extent.
When multiple still images are shown one after another, the phenomenon in which movement that did not originally exist is seen (felt) between those frames is called apparent movement*6.
*Note 6: Here, the word apparent movement is used in a broad sense. Apparent movement in the narrow sense refers to something that is moving so smoothly that the video and the actual movement cannot be distinguished. In other words, apparent movement in the narrow sense can explain things where the amount of movement between frames is small, but it is thought that other factors are also involved in phenomena where things still look like they are moving even if the amount of movement is large.
Figure 2.11 shows an example of basic apparent motion between two frames.
Figure 2.11: Basic apparent motion
- [a] Looks like a circle has moved
- [b] Looks like a rectangle is tilted
- [c] Looks like a rectangle has approached

[2] Expression of Movement

Whether in live-action or animation, in order for the world depicted there to have persuasive power, the subject must move in accordance with the laws of physics.
In the case of live-action, as long as it is filmed on Earth, the subject generally follows the general laws of physics, including gravity, without being particularly aware of it.
However, in the case of animation, it is necessary to consciously create movement in accordance with the laws of physics when creating each frame.
Among the laws of physics for animation production, the most important is the law of inertia.
This states that ``an object at rest will try to remain at rest, and an object in motion will try to remain in motion.''
From this, we can derive the properties of motion that generally when moving an object that is at rest, it will not suddenly start moving at full speed, but will gradually increase in speed,'' or conversely,when stopping an object that is moving, it will not suddenly stop, but will gradually slow down.''
Also, it can be explained by the law of inertia that long hair, clothes (skirts), and accessories (earrings) follow the movement of the human body slightly later.
Figure 2.12 shows an example of slow-in slow-out, which is one of the timing techniques in animation production.
When moving from a stationary state to a stationary state, instead of dividing the motion evenly, the beginning and end are slow and the middle is fast, thereby expressing a well-defined and natural movement.
Figure 2.12: Example of slow-in slow-out
- [a] Slow-in slow-out of movement drawing an arc
- [b] Slow-in slow-out of straight line movement
All objects have mass (weight).
When the same force is applied, a light object can be moved quickly, but it takes time to move a heavy object.
By adjusting this timing, you can express the weight of the object.
In addition to the law of inertia and mass, there is a close relationship between the laws of physics and animation expression.
You can't go wrong in thinking that developing a sense of physics will lead to good animation.
So far, we have explained the importance of the laws of physics in the expression of movement, but it is important to note that ``if it is physically correct, is it good animation?''
Rotoscoping is a technique in which animation is created by tracing each frame based on live-action footage.
Animations created using this technique should have physically correct movements, but in many cases, the movements tend to be small.
Whether the characters are hand-drawn or use dolls or CG, their shapes are subject to a certain type of deformation.
If the characters are deformed but the movements are still live-action, the balance will be lost and the movements will become small.
To maintain balance, it is necessary to apply deformation (exaggerated expression) to the movements as well.
To summarize the above, expressing movement in animation requires both knowledge of the laws of physics and the technique of exaggerated expression.

2-3: Typography

Typography refers to the visual expression of characters, such as what shape and size of characters to use and how to arrange them.
Even in CG production, there are many situations where expressions that combine CG and characters are required.
Here, we will explain character design and character composition, which are the basics of typography.

2-3-1: Typography

Typography consists of two elements: font and character composition.
It is necessary to select and adjust the optimal one for expressing the theme and concept of the work.

[1] Font

In a font, all characters in one set are designed with a unified concept.
The design of the characters is called the typeface, and the set of all characters based on that design is the font.
One font includes not only characters but also symbols, so there are about 200 characters for European fonts and 5,000 to 15,000 characters for Japanese fonts (the number of kanji included varies depending on the level and standard such as JIS*7).
Note that European fonts are called European fonts and Japanese fonts are called Japanese fonts.
*Note 7: JIS stands for Japanese Industrial Standard.
European font typefaces are broadly divided into serif typefaces, which have decorations on the ends of the characters, and sans-serif typefaces, which do not have serifs (Figure 2.13).
Serif typefaces include fonts such as Times and Century, and sans-serif typefaces include fonts such as Univers and Helvetica.
In Japanese fonts, the most representative typefaces are the Mincho typeface, in which the vertical and horizontal lines have different thicknesses, and the Gothic typeface, which consists of lines of the same thickness (Figure 2.14).
Figure 2.13: European fonts
- [a] Examples of serif typefaces
- [b] Examples of sans-serif typefaces
Figure 2.14: Japanese fonts
- [a] Examples of Mincho typefaces
- [b] Examples of Gothic typefaces

[2] Character Composition

When composing characters, set the line spacing, line spacing, line length, line alignment, character spacing, character spacing adjustment (kerning), etc., taking into account the purpose and the reader.
Line spacing is the setting for the size of the characters on one line and the spacing between the lines (Figure 2.15).
When setting line spacing, it is important to adjust the lines of text so that the eyes can smoothly follow each line and line breaks, taking into account the character size and line length.
Line alignment is the setting for which the lines of text are aligned based on which standard.
For example, you can align based on the left side or the center.
At this time, processing such as line break processing9, hanging10, and hyphenation*11 is also performed (Figure 2.16).
Character spacing is the setting for the length from the center of a character to the center of the next character (Figure 2.15).
Normally, it is adjusted so that the spacing between characters is visually even.
Also, adjusting the spacing between characters (character spacing) individually according to the shape of adjacent characters is called character spacing adjustment (kerning) (Figure 2.17).
*Note 8: There are various definitions of line spacing, such as the length from the center of a character to the center of the character on the next line, or the length from the top edge of the virtual body (the square frame that contains the character) to the top edge of the virtual body on the next line.

*Note 9: Line break processing is to adjust the breaks between characters in a line to arrange the layout. Some word processing software and DTP software adjust this automatically, but be sure to check it during layout. There are three types of line break processing. One is to move the sokuon and yoon such as tsu'' anda'' and the yakumono such as ...''!?'' to the previous line so that they do not come at the beginning of a line. The second is to send the characters such as[and]'' that are strange at the end of a line to the next line. And the third is to push the separation-prohibited characters such as numbers and English words such as 150,0100 people'' anddesign'' to the previous line or send them to the next line so that they are not broken in the middle.

*Note 10: Hanging is to make the punctuation marks at the end of a line stick out beyond the line length.

*Note 11: Hyphenation is to connect the first and second halves of a word with a hyphen when an European word is broken in the middle.

Figure 2.15: Line spacing, line spacing, character spacing, character spacing
Figure 2.16: Examples of line break processing
Figure 2.17: Kerning for European and Japanese texts