merged jonas
This commit is contained in:
@@ -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}.
|
||||
|
||||
Reference in New Issue
Block a user