added calibration in the report

report/subsections/calibration.tex

@@ -1 +1,28 @@
-\subsection{Camera calibration}
+% Here we go
+\subsection{Camera calibration}
+    The camera calibration is needed for the client during the reconstruction
+    of the 3D skeleton. The calibration consists in two steps :
+
+    \begin{enumerate}
+        \item the \textbf{internal calibration} which is the estimation of the
+        instrinsic parameters of the camera (such as the focal length, or the
+        principal point)
+
+        \item the \textbf{external calibration} which is the estimation of the
+        extrinsic parameters (the position of the camera from the chessboard)
+    \end{enumerate}
+
+    \subsubsection{Internal calibration}
+        The internal calibration is based on a program that we completed during
+        a lesson last semester. By detecting chessboards in numerous positions
+        of the camera, we are able to estimate the intrinsic parameters. This
+        programs use as input a video of a chessboard where the position of
+        camera changes, and it captures some frames where the chessboard is
+        detected. With these pictures, we estimate the intrinsic parameters.
+
+    \subsubsection{External calibration}
+        For the external calibration, we wrote a program that uses an
+        estimation of the homography to compute the extrinsical parameters of
+        the camera. One should note that what we call the \emph{extrinsical
+        parameters} are the ones that convert points from the reference of the
+        chessboard to the reference of the camera.