Elsevier

Computers & Geosciences

Volume 111, February 2018, Pages 200-212
Computers & Geosciences

Research paper
3D geospatial visualizations: Animation and motion effects on spatial objects

https://doi.org/10.1016/j.cageo.2017.11.007Get rights and content

Highlights

  • Prototype implementation of an open 3D geovisualization software application.

  • GIS handled interactivity between 3D models, feature layers and 3D terrains.

  • Dynamic virtual living geospatial worlds with animated and moving spatial objects.

  • Enhancing existing open visualization frameworks with geospatial functionalities.

  • Challenges for creating geovisualized event and phenomena simulations.

Abstract

Digital Elevation Models (DEMs), in combination with high quality raster graphics provide realistic three-dimensional (3D) representations of the globe (virtual globe) and amazing navigation experience over the terrain through earth browsers. In addition, the adoption of interoperable geospatial mark-up languages (e.g. KML) and open programming libraries (Javascript) makes it also possible to create 3D spatial objects and convey on them the sensation of any type of texture by utilizing open 3D representation models (e.g. Collada). One step beyond, by employing WebGL frameworks (e.g. Cesium.js, three.js) animation and motion effects are attributed on 3D models. However, major GIS-based functionalities in combination with all the above mentioned visualization capabilities such as for example animation effects on selected areas of the terrain texture (e.g. sea waves) as well as motion effects on 3D objects moving in dynamically defined georeferenced terrain paths (e.g. the motion of an animal over a hill, or of a big fish in an ocean etc.) are not widely supported at least by open geospatial applications or development frameworks. Towards this we developed and made available to the research community, an open geospatial software application prototype that provides high level capabilities for dynamically creating user defined virtual geospatial worlds populated by selected animated and moving 3D models on user specified locations, paths and areas. At the same time, the generated code may enhance existing open visualization frameworks and programming libraries dealing with 3D simulations, with the geospatial aspect of a virtual world.

Introduction

We have come a long way since the appearance of the first web mapping projects at the end of the 20th century (Haklay et al., 2008). The technological progress that affected crucially this area included, first of all, the tremendous increase of internet speed connections (Eha, 2013), combined with efficient image compression and presentation techniques (e.g. tiled rendering) that allowed web clients to request rich raster images associated with large spatial datasets (Batty et al., 2010). As a result, today it is a routine job to perform a virtual tour, on an unknown or inaccessible area or surface, by navigating through a browser over a three-dimensional (3D) Digital Terrain Model (DTM) or a Digital Surface Model (DSM) or a set of joined panoramic photographs.1 Secondly, the substantial progress occurred in Web Semantics and the related geospatial web services introduced by the Open Geospatial Consortium (OGC), with Web Map Service (WMS) being directly applicable and widely used, have enabled data sharing and interoperability among different fields of geosciences (Evangelidis et al., 2014). The aforementioned evolutions assisted also by the progress met in IT and hardware infrastructure extended the usage of location based services, also termed as geoservices, in people daily activities through the rapid penetration of smartphone and tablet devices. Recent studies showed that 35% of smartphone users in the five largest European economies access maps on their device (Oxera, 2013) while at the same time map usage via smartphone is growing seven times faster than via the classic web.2 In conclusion, today, technological capabilities from the one side and people daily needs from the other, justify efforts spent towards enhancing graphical representations of geospatial data over the web by providing 3D visualization and animation effects on spatial objects.

Computer graphics technologies can nowadays offer high 3D modeling visualization and animation capabilities combined with high satisfaction end-user interactivity, through a web browser. Such developments are supported by cross-platform frameworks like WebGL API,3 which are interpreted and rendered directly by any web browser compatible with World Wide Web Consortium (W3C) proven standards, without the need of installing plug-ins. The above technologies are mainly applied in recreational applications (3D Games) or applications with 3D photorealistic effects representing the real world, without maintaining the geospatial dimension of the involved objects. In other words, the graphical representations in such frameworks are not associated with a georeferenced area or map, and the geospatial aspect of the involved animated and moving objects does not have any practical value.

In the geospatial community, Digital Elevation Models (DEMs) either DTMs or DSMs are widely used over the last 25 years providing views of the ground terrain or surface along with elevation values.4 Today Geographic Information Systems (GIS) software can export DEMs into an interoperable XML-based format.5 Such way DEMs may be potentially visualized through web browsers and furthermore, managed by applications developed under the prevailing on the World Wide Web (WWW) open software development technologies. By employing 3D models that represent inanimate or animated objects and also by utilizing open libraries providing animation and movement functionalities on these objects it is possible to achieve real world geo-referenced simulations like for example a herd of animated animals moving through a forest on top of a DTM served by a WMS. The above may be enhanced with major GIS functionalities, such as the creation of thematic layers for the various different categories of 3D models along with the interactivity of these spatial models with user specified geospatial locations, paths or areas. Thus, the coupling of geospatial functionalities on the one hand, with computer graphics web technologies on the other, may be considered as a strong applied research challenge and is reflecting the clear objective of the presented work.

To achieve this, we gathered potential desirable functionalities involving both animation and moving capabilities of 3D models (spatial objects), yet not currently offered, at least in a complete, structured and usable form, by existing open web-GIS environments or Javascript (JS) libraries. For example a user selected 3D model representing an animated object (e.g. a galloping horse), scaled to fit to a 3D world created by the user (e.g. a forest in a mountain area), and also moving on a user-specified path, is one of them. To populate a user-specified area with a 3D spatial object representing for example a plant, or with an animated texture in order to simulate for example water, are additional interesting functionalities. Ideally, such functionalities and many more should be applied on user specified dynamic geospatial worlds, designed in various independent thematic layers, possessing any geographic, or not, non angular coordinates. For this reason the presented work considers also typical GIS-based capabilities to fully provide the geospatial aspect of 3D modeling visualization, animation and moving effects.

Having made the proposed work available for the research community6 it is possible to be directly exploited by acting as a supplement to existing JS libraries. For example it may extend the non geospatial libraries which focus on 3D animation (e.g. Three.js7) with geospatial functionalities. In addition it may enhance geospatial libraries that mainly focus on 3D globes and spatial data visualizations (e.g. Cesium.js8) with major GIS-based capabilities. The results of the above approach may act as a forerunner for enriching Earth Browsers with capabilities of representing 3D referenced inanimate or moving and animated spatial objects (e.g. flora and fauna) as well as phenomena simulations (weather phenomena, landslides, floods etc.)

Section snippets

Related work

Today JS has become the dominant programming language employed by the majority of websites and supported by all modern web browsers without plug-ins. The WebGL JS API, based on OpenGL,9 utilizes hardware acceleration and brings 3D to the web, standing as the base for continuously emerging Javascript visualization frameworks and libraries developed on top of it. In this respect the presented work and the related works reviewed are exclusively based on the above free web

Method

The method adopted in the present work makes use of surveying engineering and geometry fundamentals to formulate the algorithmic base that document minimum functionalities for geospatial visualizations and motion effects on spatial objects.

Application

The application of the method introduced in the previous paragraph includes the development of an experimental 'Geospatial World' in order to simulate on it, placement of stable living or inanimate spatial objects (e.g. plants, house) or motion of animated moving objects (e.g. animals).

Discussion and further developments

The present work employed the technologies related to 3D computer graphics and the existing visualization frameworks and libraries to achieve sophisticated geospatial world simulations associated with major GIS functionalities. There are of course several other interrelated issues beyond the scope and the central intentions of the whole venture that raise reasonable concerns. First of all, the algorithmic calculations were performed over a regular 3D terrain while the general case would be to

Acknowledgements

The authors wish to acknowledge financial support provided by the Research Committee of the Technological Educational Institute of Central Macedonia under grant SAT/GS/171214-263/23.

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