Motiejus Jakštys acc76df08c | ||
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Dockerfile | ||
Makefile | ||
README.md | ||
aggregate-rivers.sql | ||
amalgamate1.png | ||
bib.bib | ||
db | ||
extract-and-generate | ||
gdr2pgsql | ||
in-container | ||
init.sql | ||
layer2img.py | ||
mj-msc.tex | ||
notes.txt | ||
openmap-wm-bad.png | ||
openmap-wm-good.png | ||
rivers-10.sql | ||
rivers-50.sql | ||
rivers-250.sql | ||
slides-2021-03-29.txt | ||
test-rivers.sql | ||
test.sql | ||
vars.awk | ||
visuals.sql | ||
vu.pdf | ||
wang125.png | ||
wm.sql |
README.md
Wang–Müller algorithm in PostGIS
This is a work-in-progress implementation following "Line generalization based on analysis of shape characteristics" by Wang and Müller, 1998.
Structure
There will be 2 deliverables from this folder:
wm.sql
, the implementation.- paper
mj-msc-full.pdf
, a MSc thesis, explaining it.
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
mj-msc-full.pdf Thesis for publishing
test Unit tests (fast)
test-rivers Rivers tests (slow)
clean Clean the current working directory
clean-tables Remove tables created during unit or rivers tests
help Print this help message
wc Character and page count
refresh-rivers Refresh rivers-*.sql from Open Street Maps
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.
Building the paper (pdf)
# make -j$(nproc) mj-msc-full.pdf
mj-msc.tex
results in mj-msc-full.pdf
, which will be at some point
published. It needs quite a few dependencies, including a functioning Docker
environment, postgresql client, geopandas, pygments, osm2pgsql, poppler, and a
"quite extensive" LaTeX installation. This was tested on Debian 11.
Contributing
Please reach out to me before contributing. As of writing, this is not ready to accept broader contributions, TODO:
- Elimination operator.
- Exaggeration operator.
- Combination operator.
- CI (unlikely to happen).
- Known bug in
wm_self_crossing
: the program crashes with a river in Lithuania.
License
GPL 2.0 or later, same as PostGIS.