Doc: add section on detector geometries (cartesian, cartesian_inhomogeneous, hexagonal)

doc/usermanual/chapters/configuration.tex

@@ -283,7 +283,7 @@ which describes a rotation of \SI{45}{\degree} around the $Z$ axis, followed by
 All supported rotations are extrinsic active rotations, i.e. the vector itself is rotated, not the coordinate system. All angles in configuration files should be specified in the order they will be applied.
 \end{warning}
 
-\item The \parameter{coordinates} parameter represents the local coordinate of detectors, the coordinates can be \textbf{cartesian}, \textbf{polar}, etc. The default \parameter{coordinates} is \textbf{cartesian}.
+\item The \parameter{coordinates} parameter represents the local coordinate of detectors, the coordinates can be \textbf{cartesian}, \textbf{cartesian_inhomogeneous} or \textbf{hexagonal}. More information on detector geometries can be found in Section~\ref{sec:detector_geometries}. The default \parameter{coordinates} is \textbf{cartesian}.
 
 \item The \parameter{number_of_pixels} parameter represents a two-dimensional vector with the number of pixels in the active matrix in the column and row directions respectively.
 \item The \parameter{pixel_pitch} is a two-dimensional vector defining the size of a single pixel in the column and row directions respectively.
@@ -333,6 +333,29 @@ role = "reference"
 type = "Timepix3"
 \end{minted}
 
+\subsection{Detector Geometries}
+\label{sec:detector_geometries}
+
+Detectors with different gemetries are supported in the \corry framework and can be selected via the detector parameter `coordinates`. Currently, the supported geometries comprise the following:
+\begin{itemize}
+\item A regular matrix of rectangular pixels is defined via `coordinates = cartesian`. This is the default option.
+\item A matrix of rectangular pixels containing columns and/or rows with double sized pixels can be defined via `cartesian_inhomogeneous`. The following parameters can additionally be set to configure such a detector:
+  \begin{itemize}
+  \item The matrix `big_pixel` lists the columns and rows with double sized pixels. The following example describes a sensor with 52 x 80 pixels and larger pixels in the left, right and upper edges:
+    \begin{minted}[frame=single,framesep=3pt,breaklines=true,tabsize=2,linenos]{ini}
+      coordinates = cartesian_inhomogeneous
+      big_pixel = [[0,51],[79]]
+    \end{minted}
+  \item The resolution of clusters centered inside a large pixel can be defined via the vector `big_pixel_spatial_resolution`. This defaults to `2 * spatial_resolution`.
+  \end{itemize}
+\item Hexagonal pixel matrices are defined via `coordinates = hexagonal`. The following things have to be considered:
+  \begin{itemize}
+  \item In the current status, only symmetric hexagons are supported, with the pixel pitch in `x` and `y` forced to be equal.
+  \item No difference is made between hexagons with a flat side or a corner pointing upwards. This can be compensated for via a rotation of the detector.
+  \end{itemize}
+\end{itemize}
+
+
 \subsection{Masking Pixels Offline}
 \label{sec:masking}