Figure Environment Validator

What It Does

The Figure Environment Validator checks your LaTeX file for any usage of \begin{figure}...\end{figure} environments. This environment is not supported — you should use the \illustration{} macro instead. The validator reports an error with the line numbers of every \begin{figure} it finds.

When This Error Occurs

You will see this error when your document contains one or more \begin{figure} environments:

Found \begin{figure} on line 8. Please use \illustration{} instead.

If multiple figure environments are present, all of their line numbers will be listed:

Found \begin{figure} on lines 8, 23. Please use \illustration{} instead.

Common Causes

This error typically appears when:

• Copy-pasting from other LaTeX projects — Standard LaTeX documents use \begin{figure}, but this project expects \illustration{}.
• Following generic LaTeX tutorials — Most guides teach the figure environment by default.
• Force of habit — If you are used to writing standard LaTeX, reaching for \begin{figure} is natural.

How to Fix It

Replace every \begin{figure}...\end{figure} block with the \illustration{} macro. The macro takes three arguments:

\illustration{<width>}{<filename>}{<caption>}

• <width> — The width of the image as a fraction (e.g. .4 for 40% of the text width).
• <filename> — The image file name (e.g. judging.png).
• <caption> — The caption text, which can include LaTeX commands like \href.

Before (incorrect):

\begin{figure}
  \centering
  \includegraphics[width=0.4\textwidth]{overview.png}
  \caption{An overview of the system architecture.}
\end{figure}

After (correct):

\illustration{.4}{overview.png}{An overview of the system architecture.}%

Tip

Note the trailing % after \illustration{}. This prevents unwanted whitespace from being introduced after the macro. It is good practice to include it.