more explanations
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24
Makefile
24
Makefile
@ -40,9 +40,10 @@ RIVERS = \
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salvis-visvalingam-64-chaikin-50k \
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salvis-visvalingam-64-chaikin-50k \
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salvis-overlaid-douglas-64-chaikin-50k \
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salvis-overlaid-douglas-64-chaikin-50k \
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salvis-overlaid-visvalingam-64-chaikin-50k \
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salvis-overlaid-visvalingam-64-chaikin-50k \
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salvis-wm-50k \
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salvis-wm-250k \
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salvis-wm-250k \
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salvis-wm-overlaid-50k-zoom \
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salvis-wm-50k \
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salvis-wm-50k-nw \
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salvis-wm-50k-ne \
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salvis-wm-overlaid-250k-zoom \
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salvis-wm-overlaid-250k-zoom \
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salvis-gdr50-overlaid
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salvis-gdr50-overlaid
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@ -199,15 +200,22 @@ salvis-overlaid-visvalingam-64-chaikin-50k_1COLOR = orange
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salvis-overlaid-visvalingam-64-chaikin-50k_WIDTHDIV = 2
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salvis-overlaid-visvalingam-64-chaikin-50k_WIDTHDIV = 2
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salvis-overlaid-visvalingam-64-chaikin-50k_QUADRANT = 1
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salvis-overlaid-visvalingam-64-chaikin-50k_QUADRANT = 1
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salvis-wm-50k_1SELECT = wm_visuals where name='salvis-wm-75'
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salvis-wm-50k_WIDTHDIV = 2
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salvis-wm-250k_1SELECT = wm_visuals where name='salvis-wm-220'
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salvis-wm-250k_1SELECT = wm_visuals where name='salvis-wm-220'
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salvis-wm-250k_WIDTHDIV = 10
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salvis-wm-250k_WIDTHDIV = 10
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salvis-wm-overlaid-50k-zoom_1SELECT = wm_visuals where name='salvis-wm-75'
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salvis-wm-50k_1SELECT = wm_visuals where name='salvis-wm-75'
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salvis-wm-overlaid-50k-zoom_2SELECT = wm_visuals where name='salvis'
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salvis-wm-50k_2SELECT = wm_visuals where name='salvis'
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salvis-wm-overlaid-50k-zoom_1COLOR = orange
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salvis-wm-50k_1COLOR = orange
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salvis-wm-50k-nw_1SELECT = wm_visuals where name='salvis-wm-75'
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salvis-wm-50k-nw_2SELECT = wm_visuals where name='salvis'
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salvis-wm-50k-nw_1COLOR = orange
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salvis-wm-50k-nw_QUADRANT = 2
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salvis-wm-50k-ne_1SELECT = wm_visuals where name='salvis-wm-75'
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salvis-wm-50k-ne_2SELECT = wm_visuals where name='salvis'
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salvis-wm-50k-ne_1COLOR = orange
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salvis-wm-50k-ne_QUADRANT = 1
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salvis-wm-overlaid-250k-zoom_1SELECT = wm_visuals where name='salvis-wm-220'
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salvis-wm-overlaid-250k-zoom_1SELECT = wm_visuals where name='salvis-wm-220'
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salvis-wm-overlaid-250k-zoom_2SELECT = wm_visuals where name='salvis'
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salvis-wm-overlaid-250k-zoom_2SELECT = wm_visuals where name='salvis'
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78
mj-msc.tex
78
mj-msc.tex
@ -1378,45 +1378,49 @@ table~\ref{table:scale-halfcirlce-diameter}:
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\subsubsection{Medium-scale (1:\numprint{50000})}
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\subsubsection{Medium-scale (1:\numprint{50000})}
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\label{sec:analyzed-medium-scale}
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\label{sec:analyzed-medium-scale}
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\begin{figure}[ht]
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\begin{figure}[h!]
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\centering
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\centering
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\begin{subfigure}[b]{.49\textwidth}
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\includegraphics[width=\textwidth]{salvis-wm-50k}
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\includegraphics[width=\textwidth]{salvis-50k}
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\caption{2x zoomed-in {\WM} for 1:\numprint{50000}.}
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\caption{Original.}
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\end{subfigure}
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\hfill
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\begin{subfigure}[b]{.49\textwidth}
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\centering
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\includegraphics[width=\textwidth]{salvis-wm-50k}
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\caption{Simplified.}
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\end{subfigure}
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\caption{Simplified with {\WM} for 1:\numprint{50000}.}
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\label{fig:salvis-wm-50k}
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\label{fig:salvis-wm-50k}
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\end{figure}
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\end{figure}
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As one can see in figure~\ref{fig:salvis-wm-50k}, the illustrations deliver
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As one can see in figure~\ref{fig:salvis-wm-50k}, the illustrations deliver
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what was promised by the algorithm, but with a few caveats. West-side of the
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what was promised by the algorithm, but with a few caveats. Left side of the
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river looks reasonably well simplified: long bends remain slightly curved,
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figure looks reasonably well simplified: long bends remain slightly curved,
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small bends are removed or slightly exaggerated.
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small bends are removed or slightly exaggerated.
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Approximately at the middle of the figure some jagged and sharp bends appear.
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Figure's~\ref{fig:salvis-wm-50k} left part is clipped to
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Figure~\ref{fig:salvis-wm-50k-overlaid-zoom} zooms in, overlaying the original
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figure~\ref{fig:salvis-wm-50k-nw}. As one can see, some bends were well
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river (in orange). These will become more pronounced in even larger-scale
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exaggerated, and some bends were eliminated.
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\begin{figure}[h!]
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\centering
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\includegraphics[width=\textwidth]{salvis-wm-50k-nw}
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\caption{Left part of figure~\ref{fig:salvis-wm-50k}.}
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\label{fig:salvis-wm-50k-nw}
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\end{figure}
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Top--right side (clipped in figure~\ref{fig:salvis-wm-50k-ne}) some jagged
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and sharp bends appear. These will become more pronounced in even larger-scale
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simplification in the next section.
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simplification in the next section.
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\begin{figure}[ht]
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\begin{figure}[h!]
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\centering
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\centering
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\includegraphics[width=\textwidth]{salvis-wm-overlaid-50k-zoom}
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\includegraphics[width=\textwidth]{salvis-wm-50k-ne}
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\caption{2x zoomed-in {\WM} for 1:\numprint{50000}.}
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\caption{Top--right part of figure~\ref{fig:salvis-wm-50k}.}
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\label{fig:salvis-wm-50k-overlaid-zoom}
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\label{fig:salvis-wm-50k-ne}
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\end{figure}
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\end{figure}
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To sum up, mid-scale simplification works well for some geometries, but creates
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sharp edges for others.
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\subsubsection{Large-scale (1:\numprint{250000})}
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\subsubsection{Large-scale (1:\numprint{250000})}
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As visible in figure~\ref{fig:salvis-wm-250k}, for large-scale map, some of the
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As visible in figure~\ref{fig:salvis-wm-250k}, for large-scale map, some of the
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resulting bends look significantly exaggerated. Why is that?
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resulting bends look significantly exaggerated. Why is that?
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Figure~\ref{fig:salvis-wm-250k-overlaid-zoom} zooms in the large-scale
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Figure~\ref{fig:salvis-wm-250k-overlaid-zoom} zooms in the large-scale
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simplification and overlays the original (in orange).
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simplification and overlays the original.
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\begin{figure}[ht]
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\begin{figure}[ht]
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\centering
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\centering
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@ -1431,7 +1435,7 @@ simplification and overlays the original (in orange).
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\includegraphics[width=.2\textwidth]{salvis-wm-250k}
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\includegraphics[width=.2\textwidth]{salvis-wm-250k}
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\caption{Simplified.}
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\caption{Simplified.}
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\end{subfigure}
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\end{subfigure}
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\caption{Simplified with {\WM} for 1:\numprint{250000}.}
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\caption{GDB10LT simplified with {\WM} for 1:\numprint{250000}.}
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\label{fig:salvis-wm-250k}
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\label{fig:salvis-wm-250k}
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\end{figure}
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\end{figure}
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@ -1442,11 +1446,27 @@ simplification and overlays the original (in orange).
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\label{fig:salvis-wm-250k-overlaid-zoom}
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\label{fig:salvis-wm-250k-overlaid-zoom}
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\end{figure}
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\end{figure}
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A conglomeration of bends is visible, especially in north-east side of the
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A conglomeration of bends is visible, especially in top--right side of the
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center. We assume this was caused by two bends significantly exaggerated,
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illustration. We assume this was caused by two bends significantly exaggerated,
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leaving no space to exaggerate for those between the two. For the same reason,
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leaving no space to exaggerate for those between the two.
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the figure~\ref{fig:salvis-wm-50k} (of scale 1:\numprint{50000}) has many
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smaller bends at approximately the same location.
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\subsubsection{Discussion}
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For mid-size scales of 1:\numprint{50000}, the implemented algorithm works well
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for certain geometries, and poorly for others. This test surfaced two areas for
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future research and improvement:
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\begin{itemize}
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\item Exaggeration is sometimes creating sharp edges, especially when the
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exaggerated bend is quite small. When sharp edges are created,
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exaggeration could interpolate more points in the bend, and exaggerate
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using the interpolated points.
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\item In larger scales, when bends do not have space to exaggerate, they
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should be combined or eliminated instead.
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\end{itemize}
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\subsection{Comparing Generalized Result with National Spatial Datasets}
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\subsection{Comparing Generalized Result with National Spatial Datasets}
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@ -1547,7 +1567,7 @@ implementation:
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\item Fine-tune parameters for bend exaggeration.
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\item Fine-tune parameters for bend exaggeration.
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Section~\ref{sec:generalization-results-of-analyzed-rivers} contains
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Section~\ref{sec:generalization-results-of-analyzed-rivers} contains
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a exaggerated bends that became sharp.
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a exaggerated bends that became sharp and includes some future ideas.
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\item Research when bends should be marked as \textsc{isolated}. As is
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\item Research when bends should be marked as \textsc{isolated}. As is
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seen from examples, the current criteria is not robust enough.
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seen from examples, the current criteria is not robust enough.
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