Blueprint vs Isometric Illustration

ブループリント / アイソメトリック・イラストレーション

Blueprint comes from Technical Expression and Isometric Illustration from Diagrammatic Expression. One is style and the other technique. They are reached for with some of the same intent, which is where they get confused.

Blueprint

Blueprint — 青写真による銃弾の設計図 — Wikimedia Commons / Public domainBlueprint — University Bridge の青写真 1915, シアトル — Wikimedia Commons / CC BY 2.0Blueprint — ブザンソン大聖堂の平面図 1882, フランス国立文書館 — Wikimedia Commons / Public domain

Instead of a finished object it shows the lines of the thinking behind it, communicating structure and possibility.

Isometric Illustration

Isometric Illustration — ショワジー『建築史』のアイソメ図 1899 — Wikimedia Commons / Public domainIsometric Illustration — ハンセンのアイソメ建築図面 19世紀 — Wikimedia Commons / Public domainIsometric Illustration — アクソノメトリック建築図面（CC BY-SA 3.0）

Keeps depth while looking down from above, explaining relationships among many parts in a single image.

BlueprintIsometric Illustration
Eraindustrialtechnical drawing–digital
FamilyTechnical ExpressionDiagrammatic Expression
KindStyleTechnique
CuesWhite lines on blue / Dimensions / Sections / Handwritten notes30-degree axes / Uniform scale / Exploded views / Little worlds
Best used forVisualizing concepts, design and process · Structural credibility for products and architectureShowing the whole of a system or space · Friendly diagrams of complex relations
TypeMonospace plus drafting-style handwritingA concise sans with small labels
CompositionOrthographic views, sections, dimension lines tied to real informationFix the three axes; enlarge only what matters
MaterialDeep blue, white lines, fine paper grainValue steps per plane, thin outlines, limited color
CautionNo fake drawings as decoration. Bind everything to actual structure and thought.Don't draw everything at equal density. Pull the eye to the relation you're explaining.

Put these two together

Technical Expression ／ Diagrammatic Expression

IndexStyle