commit 250095cdbd5cf431bb2f8d9db6b72cb7b69232cb (tree)
parent 6ba9fe95663282772aa99135f071094eb23af2fe
Author: Motiejus Jakštys <motiejus@uber.com>
Date: Tue, 20 Apr 2021 18:21:07 +0300
add more river examples
Diffstat:
3 files changed, 60 insertions(+), 26 deletions(-)
diff --git a/IV/Makefile b/IV/Makefile
@@ -23,9 +23,9 @@ FIGURES = \
selfcrossing-1-after
RIVERS = \
- salvis-gdr10 \
- salvis-gdr50 \
- salvis-gdr250
+ salvis-25k \
+ salvis-50k \
+ salvis-250k
#################################
# The thesis, publishable version
@@ -121,15 +121,17 @@ selfcrossing-1-after_1SELECT = wm_debug where name='selfcrossing-1' AND stage='d
selfcrossing-1-after_2SELECT = wm_debug where name='selfcrossing-1' AND stage='bbends' AND gen=1
selfcrossing-1-after_2LINESTYLE = invisible
-salvis-gdr10_1SELECT = wm_rivers where name='Šalčia' OR name='Visinčia'
-salvis-gdr10_WMCLIP = salcia-visincia:GDR10
+salvis-25k_1SELECT = wm_rivers where name='Šalčia' OR name='Visinčia'
+salvis-25k_WMCLIP = salcia-visincia:25k
+salvis-25k_WIDTHDIV = 1
-salvis-gdr50_1SELECT = wm_rivers where name='Šalčia' OR name='Visinčia'
-salvis-gdr50_WMCLIP = salcia-visincia:GDR50
-
-salvis-gdr250_1SELECT = wm_rivers where name='Šalčia' OR name='Visinčia'
-salvis-gdr250_WMCLIP = salcia-visincia:GDR250
+salvis-50k_WIDTHDIV = 2
+salvis-50k_1SELECT = wm_rivers where name='Šalčia' OR name='Visinčia'
+salvis-50k_WMCLIP = salcia-visincia:50k
+salvis-250k_WIDTHDIV = 10
+salvis-250k_1SELECT = wm_rivers where name='Šalčia' OR name='Visinčia'
+salvis-250k_WMCLIP = salcia-visincia:250k
.faux_test-rivers: tests-rivers.sql wm.sql .faux_db
./db -f $<
diff --git a/IV/layer2img.py b/IV/layer2img.py
@@ -17,9 +17,10 @@ PSQL_CREDS = "host=127.0.0.1 dbname=osm user=osm password=osm"
TEXTWIDTH_CM = 12.12364
SCALES = {
- "GDR10": 10000,
- "GDR50": 50000,
- "GDR250": 250000,
+ "10k": 10000,
+ "25k": 25000,
+ "50k": 50000,
+ "250k": 250000,
}
def inch(cm):
@@ -52,7 +53,7 @@ def parse_args():
parser.add_argument('--wmclip',
type=wm_clip,
- help="Clip for scale. E.g. salcia-visincia:GDR10",
+ help="Clip for scale. E.g. salcia-visincia:10k",
)
parser.add_argument('--widthdiv',
default=1, type=float, help='Width divisor')
diff --git a/IV/mj-msc.tex b/IV/mj-msc.tex
@@ -85,7 +85,7 @@ Current open-source line generalization solutions have their roots in
NOTICE: this value should be copied to layer2img.py:TEXTWIDTH, so dimensions
of inline images are reasonable.
-textwidth in cm: {\printinunitsof{cm}\prntlen{\textwidth}}
+Textwidth in cm: {\printinunitsof{cm}\prntlen{\textwidth}}
\fi
When creating small-scale maps, often the detail of the data source is greater
@@ -129,7 +129,8 @@ different trade-offs.
\label{sec:literature-review}
A number of cartographic line generalization algorithms have been researched.
-The "classical" ones are {\DP} and {\VW}.
+The "classical" ones are {\DP} and {\VW} in combination with Chaikin's. There
+are also modern ones.
\subsection{Available algorithms}
@@ -150,13 +151,43 @@ Both algorithms are part of PostGIS, a free-software GIS suite:
\href{https://postgis.net/docs/ST_SimplifyVW.html}{PostGIS SimplifyVW}.
\end{itemize}
-Examples of <TBD Chaikin and others>
-
It may be worthwhile to post-process those through a widely available Chaikin's
line smoothing algorithm \cite{chaikin1974algorithm} via
\href{https://postgis.net/docs/ST_ChaikinSmoothing.html}{PostGIS
ChaikinSmoothing}.
+To use in generalization examples, we will use two rivers: Žeimena and Šalčia
+(they flow into one). Figure~\onpage{fig:salvis-25} illustrates the original
+two rivers without any processing (yet).
+
+\begin{figure}[h]
+ \centering
+ \includegraphics[width=\textwidth]{salvis-25k}
+ \caption{Example rivers for visual tests (1:25000)}
+ \label{fig:salvis-25}
+\end{figure}
+
+Same rivers, unprocessed, but with higher density (scales 1:50000 and 1:250000)
+are depicted in figure~\onpage{fig:salvis-50-250}. Some river features are so
+compact that a reasonably thin line depicting them is overlapping with itself.
+As can be seen in the article example, generalization is worthy.
+
+\begin{figure}[h]
+ \centering
+ \begin{subfigure}[b]{.49\textwidth}
+ \includegraphics[width=\textwidth]{salvis-50k}
+ \caption{Example scaled 1:50000}
+ \end{subfigure}
+ \hfill
+ \begin{subfigure}[b]{.49\textwidth}
+ \centering
+ \includegraphics[width=.2\textwidth]{salvis-250k}
+ \caption{Example scaled 1:250000}
+ \end{subfigure}
+ \caption{Down-scaled original river (1:50000 and 1:250000)}
+ \label{fig:salvis-50-250}
+\end{figure}
+
\subsubsection{Modern approaches}
@@ -359,12 +390,12 @@ when a single vertex is moved outwards the end of the bend.
\begin{figure}[h]
\centering
- \begin{subfigure}[b]{.45\textwidth}
+ \begin{subfigure}[b]{.49\textwidth}
\includegraphics[width=\textwidth]{fig5-gentle-inflection-before}
\caption{Before applying the inflection rule}
\end{subfigure}
\hfill
- \begin{subfigure}[b]{.45\textwidth}
+ \begin{subfigure}[b]{.49\textwidth}
\includegraphics[width=\textwidth]{fig5-gentle-inflection-after}
\caption{After applying the inflection rule}
\end{subfigure}
@@ -386,12 +417,12 @@ vertices to the next bend instead of one.
\begin{figure}[h]
\centering
- \begin{subfigure}[b]{.45\textwidth}
+ \begin{subfigure}[b]{.49\textwidth}
\includegraphics[width=\textwidth]{inflection-1-gentle-inflection-before}
\caption{Before applying the inflection rule}
\end{subfigure}
\hfill
- \begin{subfigure}[b]{.45\textwidth}
+ \begin{subfigure}[b]{.49\textwidth}
\includegraphics[width=\textwidth]{inflection-1-gentle-inflection-after}
\caption{After applying the inflection rule}
\end{subfigure}
@@ -427,12 +458,12 @@ following the rules of the article.
\begin{figure}[h]
\centering
- \begin{subfigure}[b]{.45\textwidth}
+ \begin{subfigure}[b]{.49\textwidth}
\includegraphics[width=\textwidth]{fig6-selfcrossing-before}
\caption{Bend's baseline (dotted) is crossing a neighboring bend}
\end{subfigure}
\hfill
- \begin{subfigure}[b]{.45\textwidth}
+ \begin{subfigure}[b]{.49\textwidth}
\includegraphics[width=\textwidth]{fig6-selfcrossing-after}
\caption{Self-crossing removed following the algorithm}
\end{subfigure}
@@ -447,12 +478,12 @@ figure~\onpage{fig:selfcrossing-1-non-neighbor}.
\begin{figure}[h]
\centering
- \begin{subfigure}[b]{.45\textwidth}
+ \begin{subfigure}[b]{.49\textwidth}
\includegraphics[width=\textwidth]{selfcrossing-1-before}
\caption{Bend's baseline (dotted) is crossing a non-neighboring bend}
\end{subfigure}
\hfill
- \begin{subfigure}[b]{.45\textwidth}
+ \begin{subfigure}[b]{.49\textwidth}
\includegraphics[width=\textwidth]{selfcrossing-1-after}
\caption{Self-crossing removed following the algorithm}
\end{subfigure}
