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Commit 8e89781a authored by even's avatar even
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Article: ADS def generalized

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......@@ -11,7 +11,7 @@
title = {Blurred segments in gray level images for
interactive line extraction},
author = {Kerautret, Bertrand and Even, Philippe},
booktitle = {Proc. of Int. Workshop on Computer Image Analysis}},
booktitle = {Proc. of Int. Workshop on Combinatorial Image Analysis},
series = {LNCS},
volume = {5852},
optpublisher = {Springer},
......
......@@ -116,9 +116,9 @@ thus producing a useless computational cost.
Here the proposed solution is to dynamically align the scan direction to
the blurred segment one all along the expansion stage.
At each iteration $i$, the scan strip is updated using the direction
of the blurred segment computed at previous iteration $i-1$.
The adaptive directional scan $ADS$ is then defined by :
At each iteration $i$, the scan strip is aligned on the direction of the
blurred segment $\mathcal{B}_{i-1}$ computed at previous iteration $i-1$.
More generally, an adaptive directional scan $ADS$ is defined by:
\begin{equation}
%S_i = \mathcal{D}_{i-1} \cap \mathcal{N}_i
ADS = \left\{
......@@ -126,14 +126,23 @@ S_i = \mathcal{D}_i \cap \mathcal{N}_i \cap \mathcal{I}
\left| \begin{array}{l}
\delta(\mathcal{N}_i) = - \delta^{-1}(\mathcal{D}_0) \\
\wedge~ h_0(\mathcal{N}_i) = h_0(\mathcal{N}_{i-1}) + p(\mathcal{D}) \\
\wedge~ \mathcal{D}_{i} = D (\mathcal{B}_{i-1},\varepsilon + k), i > 1
\wedge~ \mathcal{D}_{i} = \mathcal{D} (C_{i-1}, \vec{D}_{i-1}, w_{i-1}), i > 1
%\wedge~ \mathcal{D}_{i} = D (\mathcal{B}_{i-1},\varepsilon + k), i > 1
\end{array} \right. \right\}
\end{equation}
where $D (\mathcal{B}_i,w)$ is the scan strip aligned to the
detected segment at iteration $i$ with width $w$.
In practice, the scan width is set a little greater than the assigned
width $\varepsilon$ ($k$ is a constant arbitrarily set to 4).
The last clause expresses the update of the scan bounds at iteration $i$.
%where $D (\mathcal{B}_i,w)$ is the scan strip aligned to the
%detected segment at iteration $i$ with width $w$.
%In practice, the scan width is set a little greater than the assigned
%width $\varepsilon$ ($k$ is a constant arbitrarily set to 4).
where $C_{i-1}$, $\vec{D}_{i-1}$ and $w_{i-1}$ are a position, a director
vector and a width observed at iteration $i-1$.
In the scope of the present detector, $C_{i-1}$ is the intersection of
the input selection and the medial axis of $\mathcal{B}_{i-1}$,
$\vec{D}_{i-1}$ the support vector of the narrowest digital straight line
that contains $\mathcal{B}_{i-1}$,
and $w_{i-1}$ a value slightly greater than the minimal width of
$\mathcal{B}_{i-1}$.
So the last clause expresses the update of the scan bounds at iteration $i$.
Compared to static directional scans, the scan strip moves while
scan lines remain fixed.
This behavior ensures a complete detection of the blurred segment even
......@@ -145,15 +154,15 @@ when the orientation is badly estimated (\RefFig{fig:escape} c).
\includegraphics[width=0.48\textwidth]{Fig_notions/escapeFirst_zoom.png} &
\includegraphics[width=0.48\textwidth]{Fig_notions/escapeSecond_zoom.png} \\
\multicolumn{2}{c}{
\includegraphics[width=0.98\textwidth]{Fig_notions/escapeThird_zoom.png}}
\includegraphics[width=0.78\textwidth]{Fig_notions/escapeThird_zoom.png}}
\begin{picture}(1,1)(0,0)
{\color{dwhite}{
\put(-260,134.5){\circle*{8}}
\put(-86,134.5){\circle*{8}}
\put(-260,108.5){\circle*{8}}
\put(-86,108.5){\circle*{8}}
\put(-172,7.5){\circle*{8}}
}}
\put(-263,132){a}
\put(-89,132){b}
\put(-263,106){a}
\put(-89,106){b}
\put(-175,5){c}
\end{picture}
\end{tabular}
......@@ -195,7 +204,7 @@ $\lambda$ iterations ($\mu_{i+\lambda} = \mu_i$), it is set to a much
stricter value able to circumscribe the possible interpretations of the
segment, that take into account the digitization margins:
\begin{equation}
\varepsilon = \mu_{i+\lambda} + 1/2
\varepsilon = \mu_{i+\lambda} + \frac{\textstyle 1}{\textstyle 2}
\end{equation}
This strategy aims at preventing the incorporation of spurious outliers in
further parts of the segment.
......
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