Azure Maps:

This is a continuation of a series of articles on operational engineering aspects of Azure public cloud computing. In this article, we take a break to discuss a location service named Azure Maps. This is a full-fledged general availability service that provides similar Service Level Agreements as expected from others in the category.

Azure Maps is a collection of geospatial services and SDKs that fetches the latest geographic data and provides it as a context to web and mobile applications.  Specifically, it provides REST APIs to render vector and raster maps as overlays including satellite imagery, provides creator services to enable indoor map data publication, provides search services to locate addresses, places, and points of interest given indoor and outdoor data, provides various routing options such as point-to-point, multipoint, multipoint optimization, isochrone, electric vehicle, commercial vehicle, traffic influenced, and matrix routing, provides traffic flow view and incidents view, for applications that require real-time traffic information, provides Time zone and Geolocation services, provides elevation services with Digital Elevation Model, provides Geofencing service and mapping data storage, with location information hosted in Azure and provides Location intelligence through geospatial analytics.

SDKs are also available with flavors suited for desktop and mobile applications. Both the SDKs are quite powerful and enhance programmability. They allow customization of interactive maps that can render content and imagery specific to the publisher. The interactive map uses WebGL map control that is known for rendering large datasets with high performance. The SDKs can be used with JavaScript and TypeScript.

Location is a datatype. It can be represented either as a point or a polygon and each helps with answering questions such as getting top 3 stores near to a geographic point or stores within a region. Since it is a data type, there is some standardization available. SQL Server defines not one but two data types for the purpose of specifying location: the Geography data type and the Geometry data type.  The Geography data type stores ellipsoidal data such as GPS Latitude and Longitude and the geometry data type stores Euclidean (flat) coordinate system. The point and the polygon are examples of the Geography data type. Both the geography and the geometry data type must have reference to a spatial system and since there are many of them, it must be used specifically in association with one. This is done with the help of a parameter called the Spatial Reference Identifier or SRID for short. The SRID 4326 is the well-known GPS coordinates that give information in the form of latitude/Longitude. Translation of an address to a Latitude/Longitude/SRID tuple is supported with the help of built-in functions that simply drill down progressively from the overall coordinate span.  A table such as ZipCode could have an identifier, code, state, boundary, and center point with the help of these two data types. The boundary could be considered the polygon formed by the zip and the Center point as the central location in this zip. Distances between stores and their membership to zip can be calculated based on this center point. Geography data type also lets us perform clustering analytics which answers questions such as the number of stores or restaurants satisfying a certain spatial condition and/or matching certain attributes. These are implemented using R-Tree data structures that support such clustering techniques. The geometry data type supports operations such as area and distance because it translates to coordinates.   It has its own rectangular coordinate system that we can use to specify the boundaries or the ‘bounding box’ that the spatial index covers.

Mapping the spatial data involves rendering the data as a layer on top of images. These overlays enhance the display and provide visual aid to the end-users with geographical context. The Azure Maps Power BI provides this functionality to visualize spatial data on top of a map. An Azure Maps account is required to create this resource via the Azure Portal.

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