# Review of Web Mapping: Eras, Trends and Directions
## 3 Web Mapping Eras of Development
### Web Mapping Eras
#### 3.2.6 Digital Globe Web Mapping Era  
Arguably one of the most significant events, the Digital Globe (or sometimes named virtual globe or virtual earth) web mapping era has opened up the power of mapping to the global community. The advent of digital globes was identified by [PERSON] [26] as the third significant development in 2005 and by [PERSON] [27] as the fourth generation of web mapping. Digital globes have exploited the benefits of the emerging technologies (e.g., from Services, Interactive and Collaborative era developments) to generate an environment in which the user is provided with an immersive experience in Earth imagery, not only in 2D but also in a 3D (actually 2.5D) environment. The emergence of Google Earth, Microsoft Virtual Earth (now BING), Cesium, NASA World Wind and a host of additional virtual earth platforms, have exposed maps and digital earth imagery to the common everyday citizen and made possible real-time, synchronous sharing of views within a group of people joining a conference session. The digital globe interfaces, realistic earth imagery and public global data brought the world to the desktop, more recently to mobile devices and through web browsers, like no other previous mapping applications ever did.  
The advent of these first public web services with global coverage of digital imagery opened up the geospatial world of mapping to the public community worldwide via the Internet. The ability to generate maps expanded well beyond the small group of web developers and mapping experts. As [PERSON] [27] points out, the result is that knowledge and interest in places of experience become the realm of the average citizen, no matter where in the world they are located. The user base suddenly expanded exponentially from the specialist community to the global community, essentially anyone who has an Internet connection, which is now ubiquitous in the world. The scientific benefits of using virtual globes due to their data presentation and visualization power are also asserted by many applications. Digital globes have become a tool for grassroots mobilization, environment protection and emergency/disaster response for many non-for-profit and public organizations.  
While the number of ready-to-use or off-the-shelf virtual globes is increasing, new technologies that enable open and pervasive development of virtual globes and their applications are rapidly evolving. A number of open-source solutions, e.g., NASA World Wind, Cesium WebGL, Glob3 Mobile and osgEarth [59; 60; 61], have made the development of virtual globe applications easier. The virtual globe APIs, such as the Google Maps API first released in 2005, also enhanced access to published online imagery basemaps by developers who could incorporate shared imagery more easily into mashups and other web map interfaces. These developments strongly influenced the uptake and expansion of web mapping by a broader base of users.  
Starting with a simple three-dimensional (3D) software model or representation of the Earth viewed through desktop installations or within web browsers, the virtual globe has moved from 3D mapping, modeling and simulation to more recent integration with virtual reality (VR), gaming and Citizen Science. An example is the recent Google Earth VR project that aims at providing people with VR experience over the Google Earth platform [62]. Another example is the platform for sharing user-generated content (Figure 3) built over Nasa World Wind [63]. The collaborative platform, named Policrowd, visualizes the points of interest (POI) and related multimedia files (texts, pictures, sounds, videos), collected and contributed by the citizens through apps. Moreover, everyone can upload new comments and multimedia content to enrich and share the information related to each POI. No doubt, this era of web mapping with virtual globes still has long way to go, for example, to be adopted for time-critical applications such as self-driving with augmented reality.