mapnik-vector-tile
Advanced tools
A high performance library for working with vector tiles.
Provides C++ headers that support rendering geodata into vector tiles and rendering vector tiles into images.
libmapnik and mapnik-configlibprotobuf and protocVector tiles in this code represent a direct serialization of Mapnik layers optimized for space efficient storage and fast deserialization. For those familiar with the Mapnik API vector tiles here can be considered a named array of mapnik::featureset_ptr whose geometries have been pre-tiled.
A vector tile can consist of one or more ordered layers identified by name and containing one or more features.
Features contain attributes and geometries: either point, linestring, or polygon.
Geometries are stored as an x,y,command stream (where command is a rendering command like move_to or line_to). Geometries are clipped, reprojected into spherical mercator, converted to screen coordinates, and delta and zigzag encoded.
Feature attributes are encoded as key:value pairs which are dictionary encoded at the layer level for compact storage of any repeated keys or values. Values use variant type encoding supporting both unicode strings, boolean values, and various integer and floating point types.
Vector tiles are serialized as protobuf messages which are then zlib compressed.
The assumed projection is Spherical Mercator (epsg:3857).
apt-get install libprotobuf7 libprotobuf-dev protobuf-compiler
apt-add-repository ppa:mapnik/v2.2.0
apt-get update && apt-get install libmapnik libmapnik-dev
brew install protobuf
brew install mapnik
Just type:
make
This builds the protobuf C++ wrappers: vector_tile.pb.cc and vector_tile.pb.h
Then include vector_tile.pb.cc in your code. The rest is header only.
Run the C++ tests like:
make test
See examples in examples/c++
These require the protobuf python bindings and the rtree library
which can be installed like:
sudo apt-get install libspatialindex-dev
pip install protobuf rtree
To build and test the python example code do:
make python && make python-test
Run the example code:
python examples/python/hello-world.py
0.4.1
FAQs
Mapnik Vector Tile API
We found that mapnik-vector-tile demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 7 open source maintainers collaborating on the project.
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