Creating Scientific Figures

Create compact, print-friendly figures for academic papers using LaTeX TikZ.

Quick Start

Minimal block diagram:

\documentclass[tikz,border=2mm]{standalone}
\usetikzlibrary{arrows.meta,positioning}
\begin{document}
\begin{tikzpicture}[
  block/.style={rectangle, draw, fill=gray!15, minimum width=2cm, minimum height=0.8cm, font=\small\sffamily},
  arrow/.style={->, >=Stealth, thick}
]
  \node[block] (a) {Input};
  \node[block, right=of a] (b) {Process};
  \node[block, right=of b] (c) {Output};
  \draw[arrow] (a) -- (b);
  \draw[arrow] (b) -- (c);
\end{tikzpicture}
\end{document}

Design Principles

Key principles for academic figures:

1. Grayscale palette: Print-friendly, no color dependency
2. Compactness: Minimize whitespace, maximize information
3. Consistency: Uniform sizing, spacing, typography
4. Hierarchy: Line weight and gray levels show importance

See PRINCIPLES.md for complete design guidelines.

Implementation

TikZ Block Diagrams: See TIKZ.md for:

• Preamble setup and required packages
• Standard style definitions
• Common patterns (linear, parallel, feedback loops)
• Positioning techniques
• Edge labels and annotations

Working Example: See examples/tikz/block-diagram.tex for a complete PID control system diagram.

Standard Styles

Copy these styles to your preamble:

% Grayscale colors
\definecolor{figdark}{gray}{0.25}
\definecolor{figlight}{gray}{0.85}

% Block styles
\tikzset{
  block/.style={rectangle, draw=figdark, fill=figlight,
    minimum width=2cm, minimum height=0.8cm,
    text centered, font=\small\sffamily},
  terminal/.style={rectangle, draw=figdark, fill=white,
    minimum width=1.5cm, minimum height=0.6cm,
    text centered, font=\small\sffamily},
  arrow/.style={->, >=Stealth, thick, draw=figdark},
  group/.style={draw=gray, dashed, fill=gray!5,
    rounded corners=2pt, inner sep=8pt}
}

Common Patterns

Linear Flow

\node[block] (a) {A};
\node[block, right=of a] (b) {B};
\draw[arrow] (a) -- (b);

Feedback Loop

\node[block] (proc) {Process};
\node[block, below=of proc] (fb) {Feedback};
\draw[arrow] (proc.east) -- ++(0.5,0) |- (fb.east);
\draw[arrow] (fb.west) -| ($(proc.west)+(-0.5,0)$) -- (proc.west);

Grouped Subsystem

\node[block] (a) {A};
\node[block, right=of a] (b) {B};
\begin{scope}[on background layer]
  \node[group, fit=(a)(b), label=above:Subsystem] {};
\end{scope}

Workflow

1. Plan layout: Sketch block arrangement on paper
2. Define styles: Set up colors and node styles
3. Place nodes: Use relative positioning (right=of, below=of)
4. Draw connections: Add arrows with appropriate routing
5. Add labels: Annotate edges and groups
6. Refine spacing: Adjust for visual balance
7. Render preview: Compile the standalone figure and create a temporary PNG or JPG preview
8. Self-verify: Inspect the preview for visual quality and fix issues before finalizing
9. Test print: Verify grayscale readability

Required Self-Verification

Every figure creation task must include a local render-and-check loop before final delivery. The source may compile successfully while still having unreadable labels, overlapping arrows, awkward whitespace, or misaligned groups; the raster preview catches these problems before the user sees them.

1. Save the figure as standalone TikZ source (.tex).
2. Compile it to PDF with latexmk -pdf or pdflatex from the figure directory.
3. Convert the PDF to a temporary PNG or JPG preview using an available tool such as pdftoppm, ImageMagick magick, or convert.
4. Open/read the temporary preview image and inspect it visually.
5. Fix any quality problems, then rerender and reinspect until the preview is acceptable.
6. Keep the final .tex and requested deliverables; remove or clearly mark temporary preview files unless the user asks to keep them.

Use a temporary preview filename such as figure-name.preview.png or place previews under a temporary directory. Do not treat successful LaTeX compilation as sufficient verification.

Self-check the preview for:

• text legibility at paper scale and at 50% zoom
• no overlapping text, labels, arrows, nodes, or group boxes
• arrowheads and line routes point in the intended direction
• consistent node sizes, spacing, alignment, and margins
• enough padding between container labels and inner blocks
• compact layout without excessive whitespace or clipped content
• grayscale contrast that remains readable in print

Example verification commands:

latexmk -pdf system-diagram.tex
pdftoppm -png -singlefile -r 200 system-diagram.pdf system-diagram.preview

If latexmk is unavailable, use pdflatex. If pdftoppm is unavailable, use ImageMagick or another installed PDF-to-image converter.

File Organization

your-paper/
├── figures/
│   ├── system-diagram.tex    % Standalone TikZ source
│   └── system-diagram.pdf    % Compiled figure
└── paper.tex                 % \includegraphics{figures/system-diagram}

Compile standalone figures separately, then include as PDF for faster paper compilation.