fix some of the andriub comments

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Motiejus Jakštys 2021-05-19 22:57:50 +03:00 committed by Motiejus Jakštys
parent 2f4f31988e
commit 07081e73d9
1 changed files with 69 additions and 42 deletions

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@ -166,31 +166,47 @@ Given the discussed complexities, a fine line between under-simplification
to be found. Therein lies the complexity of simplification algorithms: all have
different trade-offs.
% TODO:
% [Magistrinio darbo tikslas - Wang-Müller algoritmo pagrindu realizuoti upių kartografinio generalizavimo sprendimą taikant atviro kodo programinę įrangą.]
%
% [Magistro darbo uždaviniai:
% * Atlikti egzistuojančių linijų supaprastinimo algoritmų vertinimą
% * Identifikuoti, su kokiomis pagrindinėmis kartografinėmis problemomis susiduriama generalizuojant upes taikant klasikinius geometrijos supaprastinimo agloritmus
% * Apibrėžti Wang-Müller algoritmo techninės realizacijos metodiką
% * Realizuoti Wang-Müller algoritmą teoriškai ir techniškai detalizuojant jį sudarančias geometrijos keitimo operacijas
% * Sukurtą algoritmo prototipą pritaikyti skirtingiems duomenų rinkiniams ir gautus rezultatus palyginti su valstybiniais duomenų rinkiniais]
%
% [Mokslinis šio darbo aktualumas - detaliai išnagrinėti, praktiškai įgyvendinti ir aprašyti Wang-Müller algoritmu aprašomi linijų supaprastinimo procesai (žingsniai), kas leidžia išplėsti kartografinės teorijos žinias apie gamtinių objektų ribų generalizavimą atsižvelgiant į jų raiškumą. Wang-Müller straipsnyje, pristatančiame algoritmą, žingsniai sprendiniai nedetalizuojami taip, kad juos būtų galima praktiškai įgyvendinti konkretiems duomenis. Šiame darbe būtent ši dalis ir konkretizuojama. Praktinis šio darbo aktualumas - išplėstos galimybės pasinaudoti atviro kodo programine įranga atlikti kartografinės generalizacijos uždavinius. Sukurtas specializuotas kartografijai linijų supaprastinimo algoritmas gali būti pritaikytas kartografų realizuojant automatinius duomenų generalizavimo sprendimus.
%
The purpose of the thesis is to implement a river generalization algorithm
on the basis of {\WM} algorithm using open-source software.
Tasks of the thesis:
\begin{itemize}
\item Evaluate existing line simplification algorithms.
\item Identify main river generalization problems using classical line
simplification algorithms.
\item Define methods of the {\WM} technical implementation.
\item Realize {\WM} algorithm technically, explaining the geometric
transformations in detail.
\item Apply the created algorithm for different datasets and compare
the results with national data sets.
\end{itemize}
Scientific relevance of this work --- the simplification processes (steps)
described by the {\WM} algorithm are analyzed in detail, practically
implemented and the implementation --- described. That expands the knowledge of
cartographic theory about the generalization of natural objects' boundaries
after their natural defining properties.
In the original {\WM} article introducing the algorithm, the steps are not
detailed in a way that can be put into practice for specific data; steps are
specified in this work. Practically this work makes it possible to use open
source software to perform cartographic line generalization. The developed
specialized cartographic line simplification algorithm can be applied by
cartographers to implement automatic data generalization solutions. Given the
open-source nature of this work, the algorithm implementation can be modified
freely.
\section{Literature Review and Problematic}
\label{sec:literature-review-problematic}
\subsection{Available algorithms}
TODO: numeracija 2.1(?) gal senas
This section reviews the classical line simplification algorithms, which,
besides being around for a long time, offer easily accessible implementations,
as well as more modern ones, which only theorize, but do not provide an
implementation.
\subsubsection{{\DP}, {\VW} and Chaikin's}
\label{sec:dp-vw-chaikin}
@ -379,33 +395,23 @@ 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.
% TODO BEGIN
% Ši dalis turi keliauti į problematiką, nes su pačiais algoritmais mažai kuo susiję
Lack of robust openly available generalization algorithm implementations poses
a problem for map creation with free software: there is not a similar
high-quality simplification algorithm to create down-scaled maps, so any
cartographic work, which uses line generalization as part of its processing,
will be of sub-par quality. We believe that availability of high-quality
open-source tools is an important foundation for future cartographic
experimentation and development, thus it it benefits the cartographic society
as a whole.
{\WM}'s commercial availability signals something about the value of the
algorithm: at least the authors of the commercial software suite deemed it
worthwhile to include it. However, not everyone has access to the commercial
software suite, access to funds to buy the commercial suite, or access to the
operating system required to run the commercial suite. PostGIS, in contrast, is
free on itself, and runs on free platforms. Therefore, algorithm
implementations that run on PostGIS or other free platforms are useful to a
wider cartographic society than proprietary ones.
% TODO END
\subsection{Problematic with generalization of rivers}
% TODO subscection: andriub: Į šį skyrių turi būti perkeltas tekstas iš From Simplification to Generalization ir mano pakomentuota dalis iš Modern approaches skyriaus.
% DONE subscection: andriub: Į šį skyrių turi būti perkeltas tekstas iš From Simplification to Generalization ir mano pakomentuota dalis iš Modern approaches skyriaus.
% TODO: [Skyriaus pradžioje pateikiama bendra informacija: Upių generalizavimo problemą galima skaidyti į dvi dalis: egzistuojantys algoritmai skirti geometrijos supaprastinimui, tačiau neturi kartografinės logikos; egzistuojantys sprendimai nėra laisvai prieinami. Atitinkamai tuomet seka tekstas iš From Simplification to Generalization skyriaus, o toliau - dalis iš Modern approaches skyriaus.
% DONE: [Skyriaus pradžioje pateikiama bendra informacija: Upių generalizavimo problemą galima skaidyti į dvi dalis: egzistuojantys algoritmai skirti geometrijos supaprastinimui, tačiau neturi kartografinės logikos; egzistuojantys sprendimai nėra laisvai prieinami. Atitinkamai tuomet seka tekstas iš From Simplification to Generalization skyriaus, o toliau - dalis iš Modern approaches skyriaus.
This section introduces the reader to simplification and generalization, and
discusses two main problems with current-day cartographic line generalization:
\begin{itemize}
\item Currently available line simplification algorithms were created
to simplify geometries, but have no cartographical knowledge.
\item Existing cartographic line generalization algorithms are not freely
accessible.
\end{itemize}
\subsubsection{Simplification versus Generalization}
It is important to note the distinction between simplification, line
generalization and cartographic generalization.
@ -448,6 +454,28 @@ line generalization deals with a single feature class, but takes into account
its geographic properties. This paper examines {\WM}'s
\titlecite{wang1998line}, a cartographic line generalization algorithm.
\subsubsection{Availablility of generalization algorithms}
Lack of robust openly available generalization algorithm implementations poses
a problem for map creation with free software: there is not a similar
high-quality simplification algorithm to create down-scaled maps, so any
cartographic work, which uses line generalization as part of its processing,
will be of sub-par quality. We believe that availability of high-quality
open-source tools is an important foundation for future cartographic
experimentation and development, thus it it benefits the cartographic society
as a whole.
{\WM}'s commercial availability signals something about the value of the
algorithm: at least the authors of the commercial software suite deemed it
worthwhile to include it. However, not everyone has access to the commercial
software suite, access to funds to buy the commercial suite, or access to the
operating system required to run the commercial suite. PostGIS, in contrast, is
free on itself, and runs on free platforms. Therefore, algorithm
implementations that run on PostGIS or other free platforms are useful to a
wider cartographic society than proprietary ones.
\subsubsection{Unfitness of line simplification algorithms}
Section~\ref{sec:dp-vw-chaikin} illustrates the current gaps with Line
Simplification algorithms for real rivers. To sum up, we highlight the
following cartographic problems from our examples:
@ -463,8 +491,7 @@ following cartographic problems from our examples:
\end{description}
We are
limiting the problem to cartographic line generalization. That is, full
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.