An effective spherical panoramic LoD model for a mobile street view service

Abstract

Street view (panoramic view) services have begun to shift from PC platforms to mobile smart devices. Considering the capabilities of smart terminal devices, a 3608 spherical level of detail (LoD) model for mobile street view services that renders panoramic images on the inner surface of a sphere via LoD is proposed in this article. Panoramic images are segmented into tiles and organized in a pyramid tile structure for LoD rendering to improve the rendering efficiency of the proposed model. A projection model between panoramic images and the spherical surface is presented to map the panoramic tiles on the spherical graticule. A street view-rendering algorithm of panoramic images is proposed with the rendering function of OpenGL for Embedded Systems (OpenGL ES).A street view service app running on Android, based on the proposed approach, is implemented to assess two aspects of the panoramic view model, namely visualization effect and efficiency. Experiment results reveal that the 3608 spherical LoD model of the panoramic image can display 3D street view scenes better than the cubic panoramic view model. The proposed model also has an excellent 3D visualization effect and high-efficiency rendering ability for mobile street view services.Therefore, it is applicable in large-scale mobile street view services both online and offline and in augmented reality navigation. K E Y W O R D S level of detail, mobile device, panoramic image, rendering, spherical, street view 1 | I NTR OD U CTI ON In the past, people expressed the real world abstractly through all types of maps, such as general, thematic, image, and 3D maps. In May 2007, in a collaboration with Stanford University called CityBlock, Google launched Google Street View (GSV) with 3608 panoramic images for the first time (Anguelov et al., 2010). The idea was to provide a street view of driving along every street in the world by taking pictures of all buildings and roadsides. At present, worldwide Transactions in GIS. 2017;21:897-915.wileyonlinelibrary.com/journal/tgis street view environments can be routinely captured with land-based mobile mapping systems (Li, Hu, & Chen, 2009;Anguelov et al., 2010). The extensive availability of street-level image data has proven the popularity of the street view environment among users; this environment delivers useful information that was not previously available. Street view (panoramic view) with a 3608 panoramic image has been and continues to be an exciting adventure in globalscale and street-level photo collection and service. As an online virtual imaging application, GSV allows a user to view and navigate through 3608 panoramic images and observe streets and neighborhoods virtually (Li et al., 2009;Fang, Li, & Zhang, 2011;Lewis, Fotheringham, & Winstanley, 2011). One can navigate forward and backward and then up and down as well as zoom in and out. Chinese Internet service providers, such as Tencent and Baidu, also recently launched panoramic view services in succession; these services can provide real 3D scenes for the exp...

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