Digital Earth Applications Research Articles

AI ethics and data governance in the geospatial domain of Digital Earth

Digital Earth applications provide a common ground for visualizing, simulating, and modeling real-world situations. The potential of Digital Earth applications has increased significantly with the evolution of artificial intelligence systems and the capacity to collect and process complex amounts of geospatial data. Yet, the widespread techno-optimism at the root of Digital Earth must now confront concerns over high-risk artificial intelligence systems and power asymmetries of a datafied society. In this commentary, we claim that not only can current debates about data governance and ethical artificial intelligence inform development in the field of Digital Earth, but that the specificities of geospatial data, together with the expectations surrounding Digital Earth applications, offer a fruitful lens through which to examine current debates on data governance and artificial intelligence ethics. In particular, we argue that for the implementation of ethical artificial intelligence and inclusive approaches to data governance, Digital Earth initiatives need to involve stakeholders and communities at the local level and be sensitive to social, legal, cultural, and institutional contexts, including conflicts that might arise within those contexts.

The Rise of Big Data and Cloud Computing

Big Data has emerged in the past few years as a new paradigm providing abundant data and opportunities to improve and/or enable research and decision-support applications with unprecedented value for digital earth applications including business, sciences and engineering. At the same time, Big Data presents challenges for digital earth to store, transport, process, mine and serve the data. Cloud computing provides fundamental support to address the challenges with shared computing resources including computing, storage, networking and analytical software; the application of these resources has fostered impressive Big Data advancements. This paper surveys the two frontiers – Big Data and cloud computing – and reviews the advantages and consequences of utilizing cloud computing to tackling Big Data in the digital earth and relevant science domains. While Big Data is responsible for data storage and processing, the cloud provides a reliable, accessible, and scalable environment for Big Data systems to function. Big Data is defined as the quantity of digital data produced from different sources of technology, for example, sensors, digitizers, scanners, numerical modeling, mobile phones, Internet, videos, social networks. Cloud Computing and Big Data are complementary to each other. Rapid growth in Big Data is regarded as a problem. Clouds are evolving and providing solutions for the appropriate environment of Big Data while traditional storage cannot meet the requirements for dealing with Big Data, in addition to the need for data exchange between various distributed storage locations. Cloud Computing provides solutions and addresses problems with Big Data. Big data and Cloud computing both the technologies are valuable on its own. Furthermore, many businesses are targeting to combine the two techniques to reap more business benefits. Both the technologies aim to enhance the revenue of the company while reducing the investment cost. While Cloud manages the local software, Big data helps in business decisions. In paper introduces the relationship between Big Data and Cloud Computing, Cloud Computing role of Big Data, advantages of Big Data and Cloud computing, cloud architecture, importance of Cloud Computing.

6th Digital Earth Summit

The papers in this proceeding are contributions written by participants at the 6th Digital Earth Summit held 7-8 July, 2016 in Beijing, China. Under the theme "Digital Earth in the Era of Big Data", the 6th Digital Earth Summit aims to provide an international platform to focus on the application and technologies of Digital Earth for new developments and advances in the context of big data. In total, over 184 abstracts were selected for presentations in “Digital Earth Application in the Context of Big Data", “Big Data and Mountain Surface Process", and “The Role of Open Standards in the Era of Big Data" at 13 scientific sessions and 2 poster sessions. The main topics of the Summit are well represented by the papers in this proceeding. The Co-Chairs of the Summit was Huadong GUO (Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences) and Alessandro ANNONI (Joint Research Center, European Commission). The Organizing Committee for the Summit was chaired by Yongwei LIU (Chinese National Committee of International Society for Digital Earth) and Xinyuan WANG (Key Laboratory of Digital Earth Sciences, Chinese Academy of Sciences).We would like to thank the International Society for Digital Earth (ISDE), the Institute of Remote Sensing and Digital Earth (RADI) of CAS, the International Centre on Space Technologies for Natural and Cultural Heritage (HIST), under the Auspices of UNESCO, the CAS-TWAS Centre of Excellence on Space Technology for Disaster Mitigation (SDIM), Integrated Research on Disaster Risk (IRDR), Chinese National Committee of ISDE, Key Laboratory of Digital Earth Sciences of CAS, without whose generous support the Summit could not have taken place. Special thanks also go to the staff at IOP Publishing Ltd., UK.

Wāhi, a discrete global grid gazetteer built using linked open data

ABSTRACTDiscrete global grid systems have become an important component of Digital Earth systems. However, previously there has not existed an easy way to map between named places (toponyms) and the cells of a discrete global grid system. The lack of such a tool has limited the opportunities to synthesize social place-based data with the more standard Earth and environmental science data currently being analyzed in Digital Earth applications. This paper introduces Wāhi, the first gazetteer to map entities from the GeoNames database to multiple discrete global grid systems. A gazetteer service is presented that exposes the grid system and the associated gazetteer data as Linked Data. A set of use cases for the discrete global grid gazetteer is discussed.

Using modular 3D digital earth applications based on point clouds for the study of complex sites

ABSTRACTThis article discusses the use of 3D technologies in digital earth applications (DEAs) to study complex sites. These are large areas containing objects with heterogeneous shapes and semantic information. The study proposes that DEAs should be modular, have multi-tier architectures, and be developed as Free and Open Source Software if possible. In DEAs requiring high reliability in the 3D measurements, point clouds are proposed as basis for the 3D Digital digital earth representation. For the development of DEAs, we propose to follow a workflow with four components: data acquisition and processing, data management, data analysis and data visualization. For every component, technological challenges of using 3D technologies are identified and solutions applied for a case study are presented. The case study is a modular 3D DEA developed for the archaeological project Mapping the Via Appia. The 3D DEA allows archaeologists to virtually analyze a complex study area.

Mt. Etna volcano high-resolution topography: airborne LiDAR modelling validated by GPS data

ABSTRACTHigh-resolution digital topography is essential for land management and planning in any type of territory as well as the reproduction of the Earth surface in a geocoded digital format that allows several Digital Earth applications. In a volcanic environment, Digital Elevation Models are a valid reference for multi-temporal analyses aimed to observe frequent changes of a volcano edifice and for the relative detailed morphological and structural analyses. For the first time, a DTM (Digital Terrain Model) and a DSM (Digital Surface Model) covering the entire Mt. Etna volcano (Italy) derived from the same airborne Light Detection and Ranging (LiDAR) are here presented. More than 250 million 3D LiDAR points have been processed to distinguish ground elements from natural and anthropic features. The end product is the highly accurate representation of Mt. Etna landscape (DSM) and ground topography (DTM) dated 2005. Both models have a high spatial resolution of 2 m and cover an area of 620 km2. The DTM has been validated by GPS ground control points. The vertical accuracy has been evaluated, resulting in a root-mean-square-error of ± 0.24 m. The DTM is available as electronic supplement and represents a valid support for various scientific studies.

Usability in 4D AR: Visualising Multi-temporal Real-time Geo-data in Augmented Reality Environments

Even though advantages of 3D visualisation of multi-temporal geo-data versus 2D approaches have been widely proven, the particular pertaining challenge of real-time visualisation of geo-data in mobile Digital Earth applications has not been thoroughly tackled so far. In the emerging field of Augmented Reality (AR), research needs comprise finding the optimal information density, the interplay between orientation data in the background and other information layers, using the appropriate graphical variables for display, or selecting real-time base data with adequate quality and suitable spatial accuracy. In this paper we present a concept for integrating real-time data into 4D (three spatial dimensions plus time) AR environments, i.e., data with “high” spatial and temporal variations. We focus on three research challenges: 1.) high-performance integration of real-time data into AR; 2.) usability design in terms of displaying spatio-temporal developments and the interaction with the application; and 3.) design considerations regarding reality vs. virtuality, visualisation complexity and information density. We validated our approach in a prototypical application and extracted several limitations and future research areas including natural feature recognition, the cross-connection of (oftentimes monolithic) AR interface developments and well-established cartographic principles, or fostering the understanding of the temporal context in dynamic 4D Augmented Reality environments.

Real-time raster projection for web maps

The virtual globe is the default visualization for Digital Earth applications, but it can only show one half of the Earth. This article introduces user-adjustable, on-the-fly projection of georeferenced raster images for web mapping and web GIS applications. This technique allows users to center a map on arbitrary locations, while still seeing the entire Earth surface. Modern web mapping libraries can apply map projection transformations to vector data in the browser, but they do not currently support the projection of raster images at interactive frame rates. We use the cross-platform WebGL (Web Graphics Library) graphics pipeline for hardware-accelerated projection of raster data in web browsers. Two algorithmic techniques – inverse per-fragment projection, and combined forward per-triangle and inverse per-fragment projection – for georeferenced raster imagery are documented. The resulting raster maps combine the ease of use and flexibility of interactive virtual globes with the ability to show the entire Earth. The adjustable projection of raster imagery allows users to observe global phenomena that are difficult to visualize on virtual globes or traditional maps with static projections.

SolidEarth: a new Digital Earth system for the modeling and visualization of the whole Earth space

Although many of the first-generation Digital Earth systems have proven to be quite useful for the modeling and visualization of geospatial objects relevant to the Earth’s surface and near-surface, they were not designed for the purpose of modeling and application in geological or atmospheric space. There is a pressing need for a new Digital Earth system that can process geospatial information with full dimensionality. In this paper, we present a new Digital Earth system, termed SolidEarth, as an alternative virtual globe for the modeling and visualization of the whole Earth space including its surface, interior, and exterior space. SolidEarth consists of four functional components: modeling in geographical space, modeling in geological space, modeling in atmospheric space, and, integrated visualization and analysis. SolidEarth has a comprehensive treatment to the third spatial dimension and a series of sophisticated 3D spatial analysis functions. Therefore, it is well-suited to the volumetric representation and visual analysis of the inner/ outer spheres in Earth space. SolidEarth can be used in a number of fields such as geoscience research and education, the construction of Digital Earth applications, and other professional practices of Earth science.

Digital earth applications in the twenty-first century

In these early years of the twenty-first century, we must look at how the truly cross-cutting information technology supports other innovations, and how it will fundamentally change the information positions of government, private sector and the scientific domain as well as the citizen. In those positions, location will be a prominent linking pin. The classical top-down system architectures of information exchange will be diluted by peer-to-peer and bottom-up channels, forcing us to rethink their designs. We should not only focus on better architectures, but need to attend to a different economy of information exchange, in which the ‘client’ is not only the information sink, but has become an important source as well. The laws of this rising ‘infoconomy’ have yet to be settled on. This special issue on ‘Digital Earth Applications: Technological design and organizational strategies’ brings together a number of papers that shed light on this future information ecosystem in which location-specific information will be exchanged between stakeholders. The introduction presents a framework that combines geoinformation streams and organisations brokering between government, science, private sector and citizens. This novel framework helps us improve the appreciation of those papers.

Rating crowdsourced annotations: evaluating contributions of variable quality and completeness

Crowdsourcing has become a popular means to acquire data about the Earth and its environment inexpensively, but the data-sets obtained are typically imperfect and of unknown quality. Two common imperfections with crowdsourced data are the contributions from cheats or spammers and missing cases. The effect of the latter two imperfections on a method to evaluate the accuracy of crowdsourced data via a latent class model was explored. Using simulated and real data-sets, it was shown that the method is able to derive useful information on the accuracy of crowdsourced data even when the degree of imperfection was very high. The practical potential of this ability to obtain accuracy information within the geospatial sciences and the realm of Digital Earth applications was indicated with reference to an evaluation of building damage maps produced by multiple bodies after the 2010 earthquake in Haiti. Critically, the method allowed data-sets to be ranked in approximately the correct order of accuracy and this could help ensure that the most appropriate data-sets are used.

On the Optimal Representation of Vector Location using Fixed-Width Multi-Precision Quantizers

Abstract. Current generation geospatial applications primarily rely on location representations that were developed for the manipulation and display of planar maps of portions of the earth’s surface. The next generation of digital earth applications will require fundamentally new technological approaches to location representation. Improvements in the efficiency of the representation of vector location can result in substantial performance increases. We examine the advantages and limitations of the most common current approach: as tuples of fixed-width floating point representations of real numbers, and identify a list of desirable design features for an optimal replacement system. These include the use of explicitly discrete integer indexes, the use of an optimal quantification scheme, and the ability to represent point locations at multiple precisions, including the capability to exactly represent key point locations, and the ability to encode multi-precision quantizations. We describe a class of planar systems that meet these criteria, which we call Central Place Indexing (CPI) systems. We then extend these systems to the sphere to provide a class of optimal known fixed-width geospatial vector location representation systems we call CPI43 systems.

Assessment of different topographic correction methods in ALOS AVNIR-2 data over a forest area

Because the removal of topographic effects is one the most important pre-processing steps when extracting information from satellite images in digital Earth applications, the problem of differential terrain illumination on satellite imagery has been investigated for at least 20 years. As there is no superior topographic correction method applicable to all areas and all images, a comparison of topographic normalization methods in different regions and images is necessary. In this study, common topographic correction methods were applied on an ALOS AVNIR-2 image of a rugged forest area, and the results were evaluated through different criteria. The results show that the simple correction methods [Cosine, Sun-Canopy-sensor (SCS), and Minnaert correction] are inefficient in exceptionally rough forests. Among the improved correction methods (SCS+C, modified Minnaert, and pixel-based Minnaert), the best result was achieved using a pixel-based Minnaert approach in which a separate correction factor in various slope angles is used. Thus, this method should be considered for topographic correction, especially in forests with severe topography.

Digital Earth and Exploration of Military Application

Digital Earth is the inevitable product which is developed with the global information technology and international military competition, it is of great significance in modern warfare and national defense construction. This paper describes the concept of Digital Earth and the environment construction of military application of Digital Earth. At last, this paper focuses on Digital Earth applications and application status in the military.

Visualization and level-of-detail of metadata for interactive exploration of Sensor Web

There are several issues with Web-based search interfaces on a Sensor Web data infrastructure. It can be difficult to (1) find the proper keywords for the formulation of queries and (2) explore the information if the user does not have previous knowledge about the particular sensor systems providing the information. We investigate how the visualization of sensor resources on a 3D Web-based Digital Earth globe organized by level-of-detail (LOD) can enhance search and exploration of information by easing the formulation of geospatial queries against the metadata of sensor systems. Our case study provides an approach inspired by geographical mashups in which freely available functionality and data are flexibly combined. We use PostgreSQL, PostGIS, PHP, and X3D-Earth technologies to allow the Web3D standard and its geospatial component to be used for visual exploration and LOD control of a dynamic scene. Our goal is to facilitate the dynamic exploration of the Sensor Web and to allow the user to seamlessly focus in on a particular sensor system from a set of registered sensor networks deployed across the globe. We present a prototype metadata exploration system featuring LOD for a multiscaled Sensor Web as a Digital Earth application.

Shaping digital earth applications through open innovation – setting the scene for a digital earth living lab

Science and policy increasingly request for sustainable development and growth. Similarly, Digital Earth undergoes a paradigm shift to an open platform that actively supports user engagement. While the public becomes able to contribute new content, we recognize a gap in user-driven validation, feedback and requirements capture, and innovative application development. Rather than defining Digital Earth applications top down, we see a need for methods and tools that will help building applications bottom up and driven by community needs. These should include a technology toolbox of geospatial and environmental enablers, which allow to access functional building blocks and content in multiple ways, but – equally important – enable the collaboration within partially unknown stakeholder networks. The validation and testing in real-life scenarios will be a central requirement when approaching the Digital Earth 2020 goals, which were articulated recently. We particularly argue to follow a Living Lab approach for co-creation and awareness rising in relation to environmental and geospatial matters. We explain why and how such a Digital Earth Living Lab could lead to a sustainable approach for developing, deploying, and using Digital Earth applications and suggest a paradigm shift for Virtual Globes becoming forums for research and innovation.

Has OpenStreetMap a role in Digital Earth applications?

Volunteered geographic information (VGI), as a special subset of crowdsourcing, has provoked interest from many scientific disciplines and industry in the past few years. OpenStreetMap (OSM) is the most famous and well supported example of a VGI project on the Internet today. As a technology, Digital Earth (DE) offers immediate access to enormous quantities of data and information, referenced by locations on the surface of the planet. One of DE's goals is to make global spatial information ubiquitously available as an essential component of democracy. OSM's mission is well positioned within this goal where OSM aims to create a freely available editable map database of the world. This paper explores the characteristics of the collaborative, crowd-based, editing of spatial data in OSM and the crowd itself. We provide some conclusions on how OSM can be best integrated into the fabric of DE.

Parallel algorithm for viewshed analysis on a modern GPU

Spatial analysis, including viewshed analysis, is an important aspect of the Digital Earth system. Viewshed analysis is usually performed on a large scale, so efficiency is important in any Digital Earth application making these calculations. In this paper, a real-time algorithm for viewshed analysis in 3D scenes is presented by using the parallel computing capabilities of a graphics processing unit (GPU). In contrast to traditional algorithms based on line-of-sight, this algorithm runs completely within the programmable 3D visualization pipeline to render 3D terrains with viewshed analysis. The most important difference is its integration of the viewshed calculation with the rendering module. Invisible areas are rendered as shadows in the 3D scene. The algorithm process is paralleled by rasterizer units in the graphics card and by vertex and pixel shaders executed on the GPU. We have implemented this method in our 3D Digital Earth system with the DirectX 9.0c API and tested on some consumer-level PC platforms with interactive frame-rates and high image quality. Our algorithm has been widely used in related systems based on Digital Earth.

Constructing a core framework of visual engine for Digital Earth system

A visual engine is the core of a Digital Earth system. There is a wide variety of functional requirements in Digital Earth system and different requirements correspond to different operations. Based on the development of the visual engine for ChinaStar, a 3D Digital China prototype software platform, and analysis of 3D Digital Earth platforms such as Google Earth, Virtual Earth, Skyline, etc, are discussed. A common core framework for a visual engine is proposed in this paper to construct a visual engine and then with this framework various Digital Earth application systems can be developed efficient. The parametric model of the Earth, scheduling and optimization in visual field, choice of 3D graphics library, and designing component-based visual engine framework of Digital Earth are discussed in detail. In addition, the relationships among these four basic components and the construction of visualization applications of Digital Earth by this method are also discussed.

Evolution and implementation of the Digital Earth vision, technology and society

Digital Earth's framework can be traced to evolutionary threads with historic foundations that fostered the fertile conceptual and technological incubation. These threads incorporate writings, such as those of the visionary engineering-genius, Buckminster Fuller, in conjunction with an array of space age developments in computers, internet and communications, satellites, and education. In 1998, when Vice President Al Gore articulated the Digital Earth Vision, he portrayed the vision based upon myriad technology factors for the intellectual foundation and sparked a worldwide phenomenon that fortuitously included the Chinese leadership's recognition and acceptance. The Beijing Declaration is recognised for its role promulgating the International Digital Earth Symposium series to promote better understanding of the impacts of Digital Earth technology and applications on behalf of all humankind. Combinations of industrial, academic, and government organisations have advanced the technological components necessary for implementing the Digital Earth Vision at a prodigious rate. Commercial leaders, such as Google, have accelerated the influence of large segments of society towards components of the Digital Earth Vision. However, challenges still remain regarding requisite collaboration on international standards for metadata, interoperability, and data formats for space and time that will affect Digital Earth implementation scenarios. Functional requirements for the model Digital Earth geobrowser remain to be fully articulated. The current paper presents an overview of the historical components, the key players on the international scene, the catalytic technological advances, and the societal response to the growth of the Digital Earth community.