Auto-displaying a large image on multiple pages

Question

I have a long UML diagram, I use the following code. The figure is about two and a half page long, but only the first page is showing, and the lower part of the figure is missing. How do I display the whole diagram in multiple page?

Exactly what code should I add?

\usepackage{graphicx} 
......
\includegraphics[height= 81.3cm, width=18cm]{myImage.png}
\captionof{figure}{Sequence Diagram}

Answer 1

I haven't a fully automated version, but the following works:

\documentclass{article}
\usepackage[a5paper,landscape]{geometry}
\usepackage{caption,graphicx,adjustbox}

\newsavebox{\bigincbox}
\newlength{\bigincht}
\sbox\bigincbox{\includegraphics[width=\textwidth]{tiger}}
\setlength{\bigincht}{\ht\bigincbox}
{\count0=\bigincht \dimen0=.8\textheight \divide\count0 by \dimen0
 \typeout{You need \number\numexpr\count0+1\relax\space chunks}}

\begin{document}
\begin{figure}
\centering
\clipbox*{0 {.5\bigincht} {\textwidth} {\bigincht}}{\usebox{\bigincbox}}
\caption{Upper half}
\end{figure}
\begin{figure}
\centering
\clipbox*{0 0 {\textwidth} {.5\bigincht}}{\usebox{\bigincbox}}
\caption{Lower half}
\end{figure}
\end{document}

Here A5 paper and landscape mode are just for giving the example. The \typeout will write on the log file how many chunks are needed. Once this is known, it's easy to build the chunks, remembering that the first argument to \clipbox* are the lower left corner and upper right corner coordinates determining the rectangle we want to see.

The .8\textwidth is just to leave some amount of space for the caption.

The tiger.pdf image can be found in the documentation directories of PSTricks.

More concrete code

Let's try with an image 81.3cm high and 18cm wide. It seems that chunks at 90% of the text height should be OK, so

\documentclass{article}
\usepackage{graphicx,adjustbox}

\newsavebox{\bigincbox}
\newlength{\bigincht}
\sbox\bigincbox{\makebox[\textwidth]{\includegraphics[width=18cm,height=81.3cm]{tiger}}}
\setlength{\bigincht}{\ht\bigincbox}
{\count0=\bigincht \dimen0=.9\textheight \divide\count0 by \dimen0
 \typeout{You need \number\numexpr\count0+1\relax\space chunks}}

\begin{document}
\begin{figure}
\centering
\clipbox*{0 {.8\bigincht} {\textwidth} {\bigincht}}{\usebox{\bigincbox}}
\caption{Chunk 1}
\end{figure}
\begin{figure}
\centering
\clipbox*{0 {.6\bigincht} {\textwidth} {0.8\bigincht}}{\usebox{\bigincbox}}
\caption{Chunk 2}
\end{figure}
\begin{figure}
\centering
\clipbox*{0 {.4\bigincht} {\textwidth} {0.6\bigincht}}{\usebox{\bigincbox}}
\caption{Chunk 3}
\end{figure}
\begin{figure}
\centering
\clipbox*{0 {.2\bigincht} {\textwidth} {0.4\bigincht}}{\usebox{\bigincbox}}
\caption{Chunk 4}
\end{figure}
\begin{figure}
\centering
\clipbox*{0 0 {\textwidth} {0.2\bigincht}}{\usebox{\bigincbox}}
\caption{Chunk 5}
\end{figure}

\end{document}

The part before \begin{document} is what must go in your preamble; remember to load the package adjustbox. The code after \begin{document} generates the five chunks. Change the captions.