If you need the same layout of seven pictures over and over again for part1 to partN and assuming the pictures in each of the /gfx/partx/ folders are called pic1 to pic7, the below code should give you an idea of a definition of a new command to help you out. Note: I have omitted label and caption from all but the first subfigure, but they may of course be included at leisure - provided the labels are constructed in a way they remain unique, i.e. including the #1 to get the parameter that was passed to the command.
\documentclass[draft]{article}
\usepackage{graphicx}
\usepackage{subcaption}
\newcommand{\includegraphicsset}[1]{%
\begin{figure*}
\centering
\begin{subfigure}[b]{\textwidth}
\centering
\includegraphics[width=\textwidth]{/gfx/part#1/pic1}
\caption[short]{the largest picture in the set}
\label{fig:set#1large}
\end{subfigure}
\\\vspace\baselineskip
\begin{subfigure}[b]{0.3\textwidth}
\centering
\includegraphics[width=\textwidth]{/gfx/part#1/pic2}
\end{subfigure}
\hfill
\begin{subfigure}[b]{0.3\textwidth}
\centering
\includegraphics[width=\textwidth]{/gfx/part#1/pic3}
\end{subfigure}
\hfill
\begin{subfigure}[b]{0.3\textwidth}
\centering
\includegraphics[width=\textwidth]{/gfx/part#1/pic4}
\end{subfigure}
\\\vspace\baselineskip
\begin{subfigure}[b]{0.3\textwidth}
\centering
\includegraphics[width=\textwidth]{/gfx/part#1/pic5}
\end{subfigure}
\hfill
\begin{subfigure}[b]{0.3\textwidth}
\centering
\includegraphics[width=\textwidth]{/gfx/part#1/pic6}
\end{subfigure}
\hfill
\begin{subfigure}[b]{0.3\textwidth}
\centering
\includegraphics[width=\textwidth]{/gfx/part#1/pic7}
\end{subfigure}
\caption{A set of pictures}
\label{fig:set#1}
\end{figure*}
}
\begin{document}
\includegraphicsset{1}
\includegraphicsset{2}
\end{document}
Using the Example-Image, this will give a layout like this:

Note: the aspect ratio of all the images is that of the original image, i.e. if your source image for the top image has the aspect ratio in your example that will be preserved with the above code.
\includegraphicsone after the other in acenterenvironment you would get that layout. – David Carlisle Jan 06 '15 at 15:44