LaTeX: Using input command for document organization

Creating and maintaining a large LaTeX document using a single .tex file can be painful. It would be wise to organize it as sections, with one or more .tex files for each section.

For example, a large Report.tex could be broken into 2 smaller sections: 01-Intro.tex and 02-Results.tex. These files can be included into the main Report.tex using the *** command like this:

% Report.tex
\input{01-Intro.tex}
\input{02-Results.tex}

If 01-Intro.tex and 02-Results.tex include a lot of images, then it might be nice to move them and their respective images/files into their own subdirectories, say 01-IntroDir and 02-ResultsDir. In that case, Report.tex is changed to:

% Report.tex
\input{01-IntroDir/01-Intro.tex}
\input{02-ResultsDir/02-Results.tex}

Note that the command just pulls the text from 01-IntroDir/01-Intro.tex into the main Report.tex for compilation. Thus, inside 01-IntroDir/01-Intro.tex commands like \includegraphics still need to provide the full path of their image relative to the main Report.tex:

% 01-IntroDir/01-Intro.tex

% Image IntroPic.png is in 01-IntroDir

% This does not work:
\includegraphics{IntroPic.png}

% This is how to correctly include:
\includegraphics{01-IntroDir/IntroPic.png}