“Old School” PNG Raster Tiles
• Just a grid of PNG images that you can slip
around…
Actual PNG Tile
From OpenStreetMap Zoomed In…
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Raster Tile
Discrete colors for each pixel.
Need a data value for each pixel…
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4
Vector Tiles
All of the relevant big players in mapping use this…
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Vector Tile
No colors at all…
It is a bunch of arrays in a 256 x 256 matrix.
[ (x1,y1), (x2,y2), (x3,y3) …]
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Here’s what we would have !
if there are two lines in a tile…
[ (x1,y1), (x2,y2), (x3,y3) …], [ (x1,y1), (x2,y2), (x3,y3) …]
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Same Tile Schema as PNG
• Same addressing scheme as PNG Tiles
• ( Google / OpenStreetMap Schema )
tileurl.com/4/2/5.png
tileurl.com/4/2/5.pbf
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Specification
• Decodes binary protocal buffer (Google)
files that adhere to the Mapobox Vector
Tile (Mapbox) Specification.
https://github.com/mapbox/vector-tile-spec
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Why not GeoJSON?
• A protocal buffer is a binary format that is
very terse and compact, so it requires
much less bandwidth than text-encoded
JSON.
• It automatically simplifies geometries
appropriately to your given zoom level.
• You cut out all of the extra data that the
renderer never even uses…
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What do the values look like?
• Data values are decoded into pixel
coordinates relative to the origin of the tile.
• If 2 points are in a pixel, it is
automatically simplified into 1 point.
• This is in a post-projection space. It is
exactly in the correct form for your
renderer…
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Each tile is a separate HTML5 Canvas.
Polygon Framgent 1
Polygon Framgent 2
of the Democratic Republic of Congo
Feature
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This means each tile is being rendered
by your GPU in parallel.
FAST!
How does this relate to MapboxGL?
• Leaflet.MapboxVectorTile renders vector
tiles as a set of canvas tile layers in Leaflet.
• MapboxGL is more advanced than Leaflet
and runs primarily from vector tiles. This
uses OpenGL / WebGL instead of HTML5
canvas to render. It is more performant, but
it is less stable than Leaflet and does not
work on Internet Exploder.
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How do I make
Mapbox Vector Tiles?
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Option 1: Mapbox Studio
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What if I need / want
to create these things
dynamically???
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The Spatial Server
(formally known as Chubbs)…
If you want Mapbox to serve it,
you need to pre-render your tiles
into .mbtiles format…
SpatialServer looks at PostGIS tables
and cuts you tiles on the fly!