Generating Orthorectified Multi-Perspective 2.5D Maps to Facilitate Web GIS-Based Visualization and Exploitation of Massive 3D City Models

Jianming Liang,Jianhua Gong,Shuisen Chen,Jun Sun,Jin Liu,Jinming Zhang,Yuling Zou

doi:10.3390/ijgi5110212

Abstract

2.5D map is a convenient and efficient approach to exploiting a massive three-dimensional (3D) city model in web GIS. With the rapid development of oblique airborne photogrammetry and photo-based 3D reconstruction, 3D city models are becoming more and more accessible. 3D Geographic Information System (GIS) can support the interactive visualization of massive 3D city models on various platforms and devices. However, the value and accessibility of existing 3D city models can be augmented by integrating them into web-based two-dimensional (2D) GIS applications. In this paper, we present a step-by-step workflow for generating orthorectified oblique images (2.5D maps) from massive 3D city models. The proposed framework can produce 2.5D maps from an arbitrary perspective, defined by the elevation angle and azimuth angle of a virtual orthographic camera. We demonstrate how 2.5D maps can benefit web-based visualization and exploitation of massive 3D city models. We conclude that a 2.5D map is a compact data representation optimized for web data streaming of 3D city models and that geometric analysis of buildings can be effectively conducted on 2.5D maps.

Highlights

Urban landscapes are highly diversified in both the horizontal and vertical dimensions [1] with the presence of water bodies, plants, buildings, and other artificial structures
The inadequacy of satellite imagery and digital elevation models (DEMs) for representing the vertical dimension led to the widespread use of 3D city models [2] in urban Geographic Information System (GIS), which typically takes the form of a virtual geographic environment [3]
With 2.5D cartography, existing massive 3D city models can be used by a wider audience and in a wider variety of contexts

Summary

Introduction

Urban landscapes are highly diversified in both the horizontal and vertical dimensions [1] with the presence of water bodies, plants, buildings, and other artificial structures. The inadequacy of satellite imagery and digital elevation models (DEMs) for representing the vertical dimension led to the widespread use of 3D city models [2] in urban GIS, which typically takes the form of a virtual geographic environment [3]. 3D GIS is already widely used for interactive exploration of 3D city models, its use in a web context faces the following technical challenges: (1) Internet data transfer limits. It takes 17 min to download 1 GB of 3D model data with an internet transfer rate of 1 MB/s. The devices and platforms that host a 3D GIS application need to meet hardware and software compatibility. Iufsleadrgien-swcaelbe 3GDISciatsy smhoodwenlsincatnhobsee uesxeadmipnlews e(FbigGuISrea2sAs,hBo)w, tnheiynwthilolsaetterxaacmt aplwesid(eFrigauurdeie2nAc,eB)a,ntdhebyenweifliltaattwraicdtear swcoidpeer oafuadpiepnlciceaatniodnbs.enTehfeitreafowried,e2r.5sDcopmeaopfsahpapvliecathtieonpso.tTehnetiraelfotorea, u2.g5mDemntapthsehvaavleutehaenpdoteexntteianldtothaeuugmseeonft ethxiestvianlgue3Dancditeyxmtenoddetlhse. use of existing 3D city models

Objectives

Methods

Conclusion