Any polygon interior ring must be oriented with the winding order opposite that of their parent exterior ring and all interior rings must directly follow the exterior ring to which they belong.
Openstreetmap Vector Tiles Code Attributes ThatUpgrade Now Docs Maps Maps SDKs for iOS for Android for Unity Mapbox GL JS Mapbox Studio Mapbox Style Spec Mapbox Tiling Service Beta Vector tiles Maps APIs Navigation Navigation SDKs for iOS for Android Navigation APIs Search Search SDKs Beta for iOS for Android Geocoding API Vision Vision SDKs Beta for iOS for Android Traffic signs All docs Help How Mapbox works Tutorials Troubleshooting Glossary Docs Maps SDK for iOS SDK for Android SDK for Unity Mapbox GL JS Mapbox Studio Mapbox Style Spec Mapbox Tiling Service Beta Vector tiles Maps APIs Navigation SDK for iOS SDK for Android Navigation APIs Search SDK for iOS Beta SDK for Android Beta Geocoding API Vision Beta SDK for iOS SDK for Android Traffic signs Help How Mapbox works Tutorials Troubleshooting Glossary All docs Vector tiles Reference Specification More Specification Versioning Format How are OpenStreetMap PBF files related to Mapbox Vector Tiles Encoding geometry Encoding attributes Winding order Implementations What the spec doesnt cover How to use vector tiles as a dataset How to encode attributes that arent strings or numbers Clipping Simplification Specification Specification A specification is an important means of setting standards around how data is stored and encoded.Like applications make assumptions about what information exists in a database, Mapbox tools make assumptions about how vector tiles store geographic information.The Mapbox Vector Tile Specification explicitly provides information about file formats extensions, projections and bounds, and the internal structure of vector tiles. This page includes: explanations of version distinctions examples of geometry encoding examples of attribute encoding an explanation of the importance of winding order a list of concepts not included in the specification Versioning The specification is versioned based on major.minor notation. The major version will be incremented with any technical change to the specification format or way it should be interpreted. Changes to the minor version will be reserved for any clarification or correction of clerical errors associated with the specification language. The major version in the specification name is synonymous with the version field in a Mapbox Vector Tile layer. See the 3.1. Layers section for more details. ![]() December 4th, 2015 The focus of version 2.0 of the Mapbox Vector Tile specification is the clarification of the intent of the intial version of the specification and the definition of interior and exterior rings within polygons. The fields within the protobuffer are more clearly defined in this version of the specification and the steps for decoders and encoders are more explicity declared. July 28, 2014 Update.proto file to match Protocol Buffer style guide, changed namespace 1.0.0 April 13, 2014 First release Format Vector tiles are encoded as Google Protobufs (PBF), which allow for serializing structured data. For clarity, Mapbox Vector Tiles use the.mvt file suffix. The specification details are largely structured around the rules implemented in the base.proto file. How are OpenStreetMap PBF files related to Mapbox Vector Tiles They are not related at all. PBFs are a format, much like XML and can take many forms. Mapbox Vector Tiles and OpenStreetMap PBFs are protobuf files, but conform to completely different specifications and are used in different ways. Encoding geometry To encode geographic information into a vector tile a tool must convert geographic coordinates, such as latitude and longitude, into vector tile grid coordinates. They encode points, lines, and polygons as x y pairs relative to the top left of the grid in a right-down manner. This is a step-by-step example showing how a single vector tile encodes geometry in the grid. Step 0 An empty vector tile The vector tile to the right is a 10x10 grid with 2 cell buffer. Lets encode some geometry to the grid starting with a blue polygon. The following commands will be relative to the pen (black dot). Openstreetmap Vector Tiles Series Of TagNext step Encoding attributes Attributes are encoded in a series of tag s that exist within a feature in the vector that have integer values that reference keys and values designating the original key:value pairs from the geometry. For large geometry, this removes redundancy for attributes that have the same keys and similar values. Take a look at the original GeoJSON FeatureCollection on the left and see how its individual parts are encoded into the proper tags of the vector tile protobuf. Many geometries are multipolygons with holes, which are also represented as polygon rings. ![]() Extracting the original data from images has been difficult on maps in the past, because of the loss of underlying metadata from the geometry that might have been used to create the image. Yet, with the introduction of client side rendering of vector tiles via GL technologies, the raw geometry data has become useful for a source of information outside of rendering. In order for renderers to appropriately distinguish which polygons are holes and which are unique geometries, the specification requires all polygons to be valid ( OGC validity ).
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