merged jonas

This commit is contained in:
2018-08-09 09:43:57 +02:00
parent bd375373ad
commit 3b15bc7798
6 changed files with 110 additions and 53 deletions

View File

@@ -16,7 +16,7 @@ and are assumed to be the center and the radius of the ball.
\begin{figure}[ht]
\includegraphics[width=\textwidth]{\fig ball-detection}
\caption{Ball detection. On the right is the binary mask}
\caption[Ball detection]{Ball detection. On the right is the binary mask}
\label{p figure ball-detection}
\end{figure}
@@ -30,13 +30,13 @@ binary mask with erosions and dilations, which allowed us to detect the ball
even over long distances.
The advantages of the presented algorithm are its speed and simplicity. The
major downside is that the careful color calibration is required for the
major downside is that a careful color calibration is required for the
algorithm to function properly. If the HSV interval of the targeted color is
too narrow, then the algorithm might miss the ball; if the interval is too
wide, then other big red-shaded objects in the camera image will be detected as
too narrow, the algorithm might miss the ball; if the interval is too
wide, other big red-shaded objects in the camera image will be detected as
the ball. A possible approach to alleviate these issues to a certain degree
will be presented further in the section \ref{p sec field detect}. To
conclude, we found this algorithm to be robust enough for our purposes, if the
conclude, we found this algorithm to be robust enough for our purposes, if a
sensible color calibration was provided.
\section{Goal Detection}
@@ -64,7 +64,7 @@ contours with the largest areas are considered further (in our experiments it
was empirically determined that $N=5$ provides good results). Furthermore, all
convex contours are rejected, since the goal is a highly non-convex shape.
After that, a check is performed, how many points are necessary to approximate
the remaining contours. The motivation behind this is the following: it is
the remaining contours. The motivation behind this is the following: It is
clearly visible that the goal shape can be perfectly approximated by a line
with 8 straight segments. On an image from the camera, the approximation is
almost perfect when using only 6 line segments, and in some degenerate cases
@@ -74,7 +74,7 @@ of line segments to be approximated is probably not the goal. The preselection
stage ends here, and the remaining candidates are passed to the scoring
function.
The scoring function calculates, how different are the properties of the
The scoring function calculates, how different the properties of the
candidates are from the properties, that an idealized goal contour is expected
to have. The evaluation is happening based on two properties. The first
property is based on the observation, that the area of the goal contour is much
@@ -90,7 +90,7 @@ scoring function can then look like the following:
The contour, that minimizes the scoring function, while keeping its value under
a certain threshold is considered the goal. If no contour scores below the
threshold, then the algorithm assumes that no goal was found. An important note
threshold, the algorithm assumes that no goal was found. An important note
is that the algorithm is designed in such a way, that the preselection and
scoring are modular, which means that the current simple scoring function can
later be replaced by a function with a better heuristic, or even by some
@@ -104,7 +104,7 @@ Figure \ref{p figure goal-detection} demonstrates the algorithm in action. On
the right is the binary mask with all found contours. On the left are the goal,
and one contour that passed preselection but was rejected during scoring.
One downside of this algorithm, is that in some cases the field lines
One downside of this algorithm is that in some cases the field lines
might appear to have the same properties, that the goal contour is expected to
have, therefore the field lines can be mistaken for the goal. We will describe,
how we dealt with this problem, in the section \ref{p sec field detect}.