Motiejus Jakštys 6945c5bd80 | ||
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COPYING | ||
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Makefile | ||
README.md | ||
aggregate-rivers.sql | ||
amalgamate1.png | ||
bib.bib | ||
db | ||
extract-and-generate | ||
gdr2pgsql | ||
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in-container | ||
init.sql | ||
layer2img.py | ||
mj-msc-full.pdf | ||
mj-msc.tex | ||
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osi-logo.pdf | ||
postgis-logo.png | ||
postgresql-logo.pdf | ||
rivers-10.sql | ||
rivers-50.sql | ||
rivers-250.sql | ||
salvis.png | ||
slides-2021-03-29.txt | ||
slides-2021-06-02.tex | ||
test-rivers.sql | ||
test.sql | ||
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visuals.sql | ||
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wm.sql |
README.md
Wang–Müller line generalization algorithm in PostGIS
This is Wang–Müller line generalization algorithm implementation in PostGIS. Following "Line generalization based on analysis of shape characteristics" by the same authors, 1998.
Status & Structure
There are 2 main pieces:
wm.sql
, the implementation.- MSc thesis
mj-msc-full.pdf
with visual examples and known issues.
It contains a few supporting files, notably:
tests.sql
synthetic unit tests.test-rivers.sql
tests with real rivers.Makefile
glues everything together.layer2img.py
converts a PostGIS layer to an embeddable image.aggregate-rivers.sql
combines multiple river objects (linestrings or multilinestrings) to a single one.init.sql
initializes PostGIS database for running the tests.rivers-*.sql
are national dataset snapshots of rivers (Makefile
contains code to update them).- ... and a few more files necessary to build the paper.
Running
make help
lists the select commands for humans. As of writing:
# make help
clean Clean the current working directory
clean-tables Remove tables created during unit or rivers tests
help Print this help message
mj-msc-full.pdf Thesis for publishing
mj-msc-gray.pdf Gray version, to inspect monochrome output
refresh-rivers Refresh river data from national datasets
test-rivers Rivers tests (slow)
test Unit tests (fast)
To execute the algorithm, run:
make test
for tests with synthetic data.make test-rivers
for tests with real rivers. You may adjust the rivers and data source (e.g. use a different country instead of Lithuania) by changing theMakefile
and the test files. Left as an exercise for the reader.
N.B. the make test-rivers
fails (see test-rivers.sql
), because with higher
dhalfcircle
values, the unionized river (salvis
) is going on top of itself,
making the resulting geometry invalid during the process.
Building the paper (pdf)
# make -j mj-msc-full.pdf
mj-msc.tex
results in mj-msc-full.pdf
. This step needs quite a few
or a container: see Dockerfile
for dependencies or in-container
to run
it all in the container.
Contributing
This repository does not accept contributoins. Please fork it. If a fork has improved the algorithm substantially, you are welcome to ping me, I will link to it in this README.
Credit
Nacionalinė Žemės Tarnyba for the river data sets.
License
GPLv2 or later.