Data Lens Developer's Guide

Introduction

Data Lens is a cloud-based API toolkit for developing sophisticated visualizations of geographically referenced data, accessible in a web browser. Raw data is queried via a REST API from the Data Lens cloud service, and transformed and aggregated to provide input to the JavaScript API, which renders the visualization. The Data Lens JavaScript API is a module that connects the HERE Maps JavaScript API to the Data Lens cloud by extending the H JavaScript namespace (found under H.datalens.*).

The following sections introduce the basic Data Lens workflow and components, and illustrates some important use cases. Each story links to a fully documented code example on the HERE Developer Portal, where you can find further examples describing the technologies offered by Data Lens.

Workflow

The following diagram illustrates the workflow and components for creating visualization apps with Data Lens.

Figure 1. Overview of Data Lens Workflow and Components

This Data Lens documentation set describes the Data Lens JavaScript API and the Data Lens REST API, including the query language that you use to process and return the data for your visualizations.

Use Case: Distribution of Mobile Signal Strength on a Heat Map

Figure 2. Distribution of Mobile Network Signal Strengths on a Heat Map (click the image to go to the code example)

This use case displays a visualization of mobile network signal strength on a map. The dataset used for the visualization represents a set of geographical points and signal strength measurements taken at each point. The data points are aggregated per pixel and, where multiple points are represented on one pixel, the points' signal strength measurements are averaged. The data is fetched from the Data Lens cloud and represented on a heat map that plots an interpolation of signal strength. Color-coding indicates the average signal strengths, and opacity indicates the confidence in these interpolated averages.

Use Case: Distribution of Averaged Mobile Signal Strengths on a Raster Map

Figure 3. Distribution of Mobile Network Signal Strengths on a Raster Map (click the image to go to the code example)

This use case is similar to the previous example: it displays a visualization of mobile network signal strength on a map. In this case, the data points are first mapped to geographical squares of 250x250 meters, and the signal strength measurements of all points in each square are averaged. The data is fetched from the Data Lens cloud and represented on a raster map that displays a distribution of average signal strength.

Use Case: Visualize Mobile Network Antennae Grouped by Providers

Figure 4. Visualization of Mobile Network Antennae using Markers (click the image to go to the code example)

This use case displays a visualization of groups of mobile network antennae on a map. The dataset used for the visualization contains antenna attributes such as its location, provider and technology. Single antennae are represented by colored circles, while groups of antennae ("clusters") are represented by pie chart symbols ("categorical markers"). The end-user can filter the antennae in the viewport by cell technology (2G, 3G, 4G) using check boxes. The data served to the client is only that required for the current viewport. The data is clustered by location on the client-side, and the clustered data points are categorized and markers are created to represent the categorization.

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