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76 lines
2.8 KiB
Markdown
76 lines
2.8 KiB
Markdown
tippecanoe
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==========
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Build vector tilesets from large collections of GeoJSON features.
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Usage
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-----
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tippecanoe -o file.mbtiles [file.json]
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If the file is not specified, it reads GeoJSON from the standard input.
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The GeoJSON features need not be wrapped in a FeatureCollection.
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You can concatenate multiple GeoJSON features or files together,
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and it will parse out the features and ignore whatever other objects
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it encounters.
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Options
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-------
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* -l <i>name</i>: Layer name (default "file" if source is file.json)
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* -n <i>name</i>: Human-readable name (default file.json)
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* -z <i>zoom</i>: Base zoom level (default 14)
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* -Z <i>zoom</i>: Lowest zoom level (default 0)
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* -d <i>detail</i>: Detail at base zoom level (default 12, for tile resolution of 4096)
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* -D <i>detail</i>: Detail at lower zoom levels (default 10, for tile resolution of 1024)
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* -x <i>name</i> Property (removes the named properties from all features)
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* -X: Exclude all properties
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* -f: Force: Delete existing mbtiles file if it already exists.
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* -r <i>rate</i>: Rate at which dots are dropped at lower zoom levels (default 2.5)
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Example
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-------
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tippecanoe -o alameda.mbtiles -l alameda -n "Alameda County from TIGER" -z13 tl_2014_06001_roads.json
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cat tiger/tl_2014_*_roads.json | tippecanoe -o tiger.mbtiles -l roads -n "All TIGER roads, one zoom" -z12 -Z12 -d14 -x LINEARID -x RTTYP
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Geometric simplifications
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-------------------------
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At every zoom level, line and polygon features are subjected to Douglas-Peucker
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simplification to the resolution of the tile.
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For point features, it drops 1/2.5 of the dots for each zoom level above the base.
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I don't know why 2.5 is the appropriate number, but the densities of many different
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data sets fall off at about this same rate. You can use -r to specify a different rate.
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For line features, it drops any features that are too small to draw at all.
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This still leaves the lower zooms too dark (and too dense for the 500K tile limit,
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in some places), so I need to figure out an equitable way to throw features away.
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Any polygons that are smaller than a minimum area (currently 9 square subpixels) will
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have their probability diffused, so that some of them will be drawn as a square of
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this minimum size and others will not be drawn at all, preserving the total area that
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all of them should have had together.
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Features in the same tile that share the same type and attributes are coalesced
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together into a single geometry. You are strongly encouraged to use -x to exclude
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any unnecessary properties to reduce wasted file size.
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If a tile is larger than 500K, it will try encoding that tile at progressively
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lower resolutions before failing if it still doesn't fit.
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Development
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-----------
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Requires protoc (brew install protobuf or apt-get install libprotobuf-dev),
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and sqlite3 (apt-get install libsqlite3-dev). To build:
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make
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and perhaps
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make install
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