Contents
What are nodes on a map?
A node is one of the core elements in the OpenStreetMap data model. It consists of a single point in space defined by its latitude, longitude and node id. A third, optional dimension (altitude) can also be included: key:ele (abrev. for “elevation”).
What is way in OSM?
An OSM way is specified by a collection of nodes. The way is made up by the way segments connecting these nodes. Each segment is assumed to be the shortest line on the Earth’s surface (negating terrain issues) connecting its two ends, i.e. a geodesic on the figure of the Earth used.
What are the features of a mind map?
Mind maps can be created in many different ways, but they share the same basics:
- Central theme. A central theme is placed in the centre of a blank page.
- Associations. From the central theme associations radiate out.
- Curved lines. Associations are often drawn as curved lines.
- Keywords.
- Proximity.
- Color & images.
What is a node in a city?
Nodes are central or connecting points in a neighbourhood that have a mix of residential, commercial and institutional buildings, such as shopping areas, community centres, libraries and medium to high density housing.
What is OpenStreetMap data?
OpenStreetMap (OSM) is a collaborative project to create a free editable map of the world. Users may collect data using manual survey, GPS devices, aerial photography, and other free sources, or use their own local knowledge of the area. This crowdsourced data is then made available under the Open Database License.
Why is the PBF format chosen for OpenStreetMap?
The underlying file format is chosen to support random access at the ‘fileblock’ granularity. Each file-block is independently decodable and contains a series of encoded PrimitiveGroups, with each PrimitiveGroup containing ~8k OSM entities in the default configuration.
How to encode OSM entities into Protocol Buffers?
To encode OSM entities into protocol buffers, I collect a series of PrimitiveGroup entities to form a PrimitiveBlock, which is serialized into the Blob portion of an ‘OsmData’ fileblock. When creating a PBF file, you need to extract all strings (key, value]
Where are the type strings stored in OSM?
There are currently two fileblock types for OSM data. These textual type strings are stored in the type field in the BlobHeader: OSMHeader: The Blob Contains a serialized HeaderBlock message (See osmformat.proto). Every fileblock must have one of these blocks before the first ‘OSMData’ block.