66 lines
2.0 KiB
Markdown
66 lines
2.0 KiB
Markdown
Wang–Müller algorithm in PostGIS
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This is a work-in-progress implementation following "Line generalization based
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on analysis of shape characteristics" by Wang and Müller, 1998.
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Structure
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---------
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There will be 2 deliverables from this folder:
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- `wm.sql`, the implementation.
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- paper `mj-msc-full.pdf`, a MSc thesis, explaining the whole thing.
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It contains a few supporting files, notably:
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- `tests.sql` for synthetic unit tests.
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- `test-rivers.sql` for tests with real rivers.
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- `Makefile` to glue everything together.
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- `layer2img.py` converts a PostGIS layer to an embeddable image.
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- `init.sql` initializes PostGIS database for running the tests.
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- `rivers.sql` is an OpenStreetMap snapshot of select rivers (`Makefile`
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contains code to update them).
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- ... and a few more files to build the paper.
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Running it
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----------
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`make help` lists the most interesting commands for humans. As of writing:
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```
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$ make help
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mj-msc-full.pdf Thesis for publishing
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test Unit tests (fast)
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test-rivers Rivers tests (slow)
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clean Clean the current working directory
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clean-tables Remove tables created during unit or rivers tests
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help Print this help message
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wc Character and page count
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refresh-rivers Refresh rivers.sql from Open Street Maps
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```
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To execute the algorithm, run:
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- `make test` for tests with synthetic data.
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- `make test-rivers` for tests with real rivers. You may adjust the rivers and
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data source (e.g. use a different country instead of Lithuania) by changing
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the `Makefile` and the test files. Left as an exercise for the reader.
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Building the paper (pdf)
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------------------------
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```
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$ make -j$(nproc) mj-msc-full.pdf
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```
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`mj-msc.tex` results in `mj-msc-full.pdf`, which will be at some point
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published. It needs quite a few dependencies, including a functioning Docker
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environment, postgresql client, geopandas, and a pretty complete LaTeX
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installation.
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License
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-------
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Same as QGIS and PostGIS: GPL 2.0 or later.
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