# Origami Diagram (折り図)

> The dotted-line-and-arrow language systematized by Akira Yoshizawa for writing three-dimensional folding onto flat pages. Mountain and valley folds read across languages, and the crease pattern became an object of mathematics.

- IndexStyle No.428 — https://indexstyle.org/styles/origami-diagram
- Kind: Style · Family: Diagrammatic Expression · Era: 1950s–
- Mood: Technology, Play, Calm
- Color cues: #e9e6dd / #67635d / #171615 (cues taken from reference works, not a fixed palette)

## Defining characteristics

- Mountain and valley line styles
- Arrows guiding each step
- Sequential step diagrams
- The geometry of crease patterns

## Best used for

- Comparing primary sources and canonical works
- Extracting principles that transfer to other media

## Research method

This entry records a historical style; derive the treatment from its sources rather than a fixed recipe:

- Observe the letters, signs and scale of reference works
- Extract the one structure that governs gaze and information
- Verify the materials and behaviors specific to era, region and process

## What to avoid

Don't reduce it to surface signs. Verify the context of era, region, technology and makers.

## Application checklist

Before calling a piece an application of this style, check it against the defining characteristics:

- [ ] Mountain and valley line styles
- [ ] Arrows guiding each step
- [ ] Sequential step diagrams
- [ ] The geometry of crease patterns
- [ ] At least one reference work below has been studied directly
- [ ] The caution above ("What to avoid") has been addressed

## Related styles

- **Blueprint (ブループリント)** — Shows the lines of thinking rather than the finished thing — structure and possibility. → https://indexstyle.org/styles/blueprint
- **Jianzhi (Chinese Paper Cutting) (剪紙)** — Chinese paper cutting in red: window flowers for the New Year, auspicious patterns and stories composed from connected lines alone — positive-negative figure design still transmitted as intangible heritage. → https://indexstyle.org/styles/jianzhi

## Further study

- Yoshizawa and the Yoshizawa-Randlett system
- Robert Lang's computational origami
- the diagrams' international legibility

## Reference works

- 折り紙の展開図（CC BY 4.0） — https://commons.wikimedia.org/wiki/File:Crease%20pattern%20swordsman.svg
- 折りの幾何学（CC BY-SA 4.0） — https://commons.wikimedia.org/wiki/File:Group1-Origami%20The%20Beloch%20Fold.png

## Source of record

- OrigamiUSA — https://origamiusa.org/

## Machine surfaces

- JSON: https://indexstyle.org/api/styles/origami-diagram
- Image-generation prompt (legally clean): https://indexstyle.org/styles/origami-diagram/prompt.txt
- MCP: https://indexstyle.org/mcp (tools: search_styles, get_style, compose_styles; prompts: image-prompt, apply-style)

## 日本語

吉澤章が体系化した点線と矢印の言語で、立体の折り工程を平面に記す図法。山折り・谷折りの記号法は言語を超えて通じ、展開図（クリースパターン）は数学の対象にまでなった。

特徴: 山折り・谷折りの線種／工程を導く矢印／段階図の連続／展開図の幾何学
注意: 表面的な記号へ還元せず、時代・地域・技術・制作主体の文脈を確認する。