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Motiejus Jakštys 2021-05-11 23:59:26 +03:00
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@ -321,6 +321,13 @@ figure~\onpage{fig:salvis-generalized-chaikin-50k}.
\label{fig:salvis-overlaid-generalized-chaikin-50k}
\end{figure}
\begin{figure}[b!]
\centering
\includegraphics[width=.9\textwidth]{amalgamate1}
\caption{Narrow bends amalgamating into large unintelligible blobs.}
\label{fig:pixel-amalgamation}
\end{figure}
The resulting simplified and smoothened example
(figure~\onpage{fig:salvis-generalized-chaikin-50k}) yields a more
aesthetically pleasing result, however, it obscures natural river features.
@ -351,12 +358,6 @@ classical algorithms would remove these bends altogether. A cartographer would
retain a few of those distinctive bends, but would increase the distance
between the bends, remove some of the bends, or both.
\begin{figure}[ht]
\includegraphics[width=\textwidth]{amalgamate1}
\caption{Narrow bends amalgamating into large unintelligible blobs.}
\label{fig:pixel-amalgamation}
\end{figure}
For the reasons discussed in this section, the "classical" {\DP} and {\VW} are
not well suited for natural river generalization, and a more robust line
generalization algorithm is worthwhile for to look for.
@ -385,8 +386,6 @@ have emerged. These modern replacements fall into roughly two categories:
\end{itemize}
% TODO: [Šioje vietoje turi būti WM algoritmo pristatymas su iliustracijomis. Turi būti bent minimalus, ne sakinio, paaiškinimas, kodėl algoritmas tinkamas kartografijai. Kodėl jis pasirinktas realizuoti - o čia ir Tomas ir aš buvome parašę email: išlaikant raiškius naturalių objektų kontūrus, generalizacijos rezultatas žemėlapyje geriau atspindi gamtinės aplinkos savybes, pvz. upių vingiuotumą, kuris gali atspindėti reljefo bei kitas paviršiaus savybes ir pan.]
Authors of most of the aforementioned articles have implemented the
generalization algorithm, at least to generate the illustrations in the
articles. However, code is not available for evaluation with a desired data
@ -395,6 +394,34 @@ set, much less for use as a basis for creating new maps. To author's knowledge,
purchase of the commercial product suite, without a way to license the
standalone algorithm.
{\WM} algorithm was created by encoding professional cartographers' knowledge
into a computer algorithm. It has a few main properties which make it
especially suitable for generalization of natural linear features:
\begin{itemize}
\item Small bends are not always removed, but either combined (for example,
3 bends into 2), exaggerated, or removed, depending on the neighboring
bends.
\item Long and gentle bends are not straightened, but kept as-is.
\end{itemize}
\begin{figure}[h]
\centering
\includegraphics[width=.8\textwidth]{wang125}
\caption{Originally figure 12.5: cartographic line generalization example.}
\label{fig:wang125}
\end{figure}
As a result of these properties, {\WM} algorithm retains the defining
properties of the natural features; high-current rivers keep their appearance
as such, instead of becoming canals; low-stream bendy rivers retain their
frequent small bends.
Figure~\ref{fig:wang125} (from the original \titlecite{wang1998line})
illustrates the {\WM} algorithm (the figure labeled "proposed method").
% TODO DONE: [Šioje vietoje turi būti WM algoritmo pristatymas su iliustracijomis. Turi būti bent minimalus, ne sakinio, paaiškinimas, kodėl algoritmas tinkamas kartografijai. Kodėl jis pasirinktas realizuoti - o čia ir Tomas ir aš buvome parašę email: išlaikant raiškius naturalių objektų kontūrus, generalizacijos rezultatas žemėlapyje geriau atspindi gamtinės aplinkos savybes, pvz. upių vingiuotumą, kuris gali atspindėti reljefo bei kitas paviršiaus savybes ir pan.]
\subsection{Problematic with generalization of rivers}
% DONE subscection: andriub: Į šį skyrių turi būti perkeltas tekstas iš From Simplification to Generalization ir mano pakomentuota dalis iš Modern approaches skyriaus.
@ -495,19 +522,10 @@ We are limiting the problem to cartographic line generalization. That is, full
cartographic generalization, which takes topology and other feature classes
into account, is out of scope.
Figure~\ref{fig:wang125} illustrates {\WM} algorithm from their original
Figure~\onpage{fig:wang125} illustrates {\WM} algorithm from their original
paper. Note how the long bends retain curvy, and how some small bends got
exaggerated.
\begin{figure}[ht]
\centering
\includegraphics[width=.8\textwidth]{wang125}
\caption{Originally figure 12.5: cartographic line generalization example.}
\label{fig:wang125}
\end{figure}
\section{Methodology}
\label{sec:methodology}
% andriub: Šio skyriaus poskyriai turėtų būti išdėstyti tokia tvarka: