65 lines
2.6 KiB
Markdown
65 lines
2.6 KiB
Markdown
# Geo3DP
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Open model generator for 3D printable geography based on OpenStreetMap.
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## Downloading GIS Data
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Geo3DP requires 2 types of data files as input:
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- OpenStreetMap data as a .osm.pbf file. Available via
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[OSM by the Slice](https://slice.openstreetmap.us/).
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- Elevation data as a GeoTiff file. Available from the SRTM GL1 dataset via
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[OpenTopography](https://portal.opentopography.org/raster?opentopoID=OTSRTM.082015.4326.1).
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## Usage
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The included Dockerfile takes care of installing dependencies. To run with
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Docker, (using the ./data folder for input and output files):
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```sh
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docker build -t geo3dp:latest ./
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docker run --rm -it -v "$(pwd)/data:/app/data" geo3dp:latest \
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--osm "/app/data/<name of .osm.pbf file>" \
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--topo "/app/data/<name of .tif file>" \
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--bbox="<min. longitude>,<min. latitude>,<max. longitude>,<max. latitude>" \
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--edge-len "<length of long edge of model, typically in mm>" \
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--output "/app/data/output.stl"
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```
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- Latitudes and longitudes are encoded as decimals. That is, values south of the
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equator or west of the prime meridian are expressed as negative numbers.
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- Note the "=" and quotes on the `--bbox` argument so that negative numbers are
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not parsed as separate CLI arguments.
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Other available options include:
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- `--square`: crops the model area to a square centered within the bounding box
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- `--baseplate-h`: adjusts the height of the rectangular base
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- `--water-cutouts`: creates through holes where there are water features
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## Parallel Rendering
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To improve performance, Geo3DP automatically splits the model area into multiple
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tiles to parallelize rendering across available CPU cores. In general, the more
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CPU cores available to the Docker engine, the faster a model will render. The
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number of tiles per side can be adjusted manually with the `--slices` option.
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Refer to `--help` for more details.
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## Known Issues
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### Combining Rendered Meshes
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Due to limitations of the OpenSCAD STL exporter/importer, Geo3DP does not
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perform a proper union calculation of the resulting tiled geometry, but rather
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combines the tiled meshes by aligning them side-by-side. This results in a final
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STL file with a nonsensical internal geometry, but 3D printing slicers don't
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seem to mind. This issue may be at least partially addressed by running with
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`--slices=1` to turn off tiling.
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### Topography Smoothing
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Geo3DP applies simplistic smoothing to the computed elevation map to mitigate
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artifacts in the GeoTiff data. The smoothing algorithm works well in most cases,
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but could be improved to better handle smoothing at the edges of the model and
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consistency across varying map resolutions.
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