Digital Advertising Lecture for Advanced Digital & Social Media Strategy at U...
Geojson
1. Group members:
Bitf11a001 Muhammad Taqi
Bitf11a002 Waqas ali
Bitf11a004 Husnain haider
Bitf11a006 Saddam hussain
Bitf11a008 Hasssan mustafa
Bitf11a009 Muhammad aamir
2.
A GeoJSON object may represent a geometry, a
feature, or a collection of features.
GeoJSON supports the following geometry types:
Point, LineString, Polygon, MultiPoint,
MultiLineString, MultiPolygon, and
GeometryCollection.
Features in GeoJSON contain a geometry object and
additional properties, and a feature collection
represents a list of features.
Introduction
3.
GeoJSON is a format for encoding a variety of
geographic data structures.
JavaScript Object Notation (JSON), and the terms
object, name, value, array, and number, are defined
inIETF RFC 4627.
The key words "MUST", "MUST NOT",
"REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
"SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted
as described in IETF RFC 2119.
Definition
4.
GeoJSON always consists of a single object. This
object represents a geometry, feature, or collection of
features.
The GeoJSON object may have any number of
members (name/value pairs).
The GeoJSON object must have a member with the
name "type". This member's value is a string that
determines the type of the GeoJSON object.
Geojson objects
5.
The value of the type member must be one
of: "Point", "LineString", "Polygon“ etc.
A GeoJSON object may have an optional "crs“
member, the value of which must be a coordinate
reference system object.
A GeoJSON object may have a "bbox" member, the
value of which must be a bounding box array.
Cont..
6.
A geometry is a GeoJSON object where the type
member's value is one of the following
strings: "Point","MultiPoint", "LineString", "Geometry
Collection“ etc.
A GeoJSON geometry object of any type other
than "GeometryCollection" must have a member
with the name"coordinates". The value of the
coordinates member is always an array.
Geometry objects
7.
Positions:
A position is the fundamental geometry construct.
The "coordinates" member of a geometry object is
composed of one position (Point).
Point:
single postion
Multipoint:
Array of positions
Linestring
Array of two or more positions.
Cont..
8.
Multilinestring:
Array of linestring coordinates of array
Polygon:
Array of line ring coordinates of arrays
Multipolygon:
Array of polygon coordinates arrays.
Geometry collections:
A geometry collection must have a member with the
name "geometries". The value corresponding to
"geometries" is an array. Each element in this array is a
GeoJSON geometry object.
Cont..
9.
A feature object must have a member with the
name "geometry". The value of the geometry
member is a geometry object or a JSON null value.
A feature object must have a member with the
name "properties". The value of the properties
member is an object.
If a feature has a commonly used identifier, that
identifier should be included as a member of the
feature object with the name "id".
Feature objects
10.
A GeoJSON object with the type "FeatureCollection“
is a feature collection object.
An object of type "FeatureCollection" must have a
member with the name "features". The value
corresponding to "features" is an array.
Feature collection objects
11.
Must be a json object
If no object then parent
Default is geographic coordinate system.
Should be top level json object
Mandatory things are type and properties.
Coordinates reference system objects
12.
Named crs
"crs":
{ "type": "name",
"properties":
{ "name": "urn:ogc:def:crs:OGC:1.3:CRS84" } }
Linked crs
Value of its property must be link object.
Types
13.
Link object
"href" member must be a dereferenceable URI
"crs":
{ "type": "link",
"properties":
{ "href": "data.crs",
"type": "ogcwkt" } }
Cont..
14.
To include information on the coordinate range for
geometries, features, or feature collections, a
GeoJSON object may have a member named "bbox".
Bounding boxes
