Abstract
Abstract. Accessing 3D geospatial models, eventually at no cost and for unrestricted use, is certainly an important issue as they become popular among participatory communities, consultants, and officials. Various geo-portals, mainly established for 2D resources, have tried to provide access to existing 3D resources such as digital elevation model, LIDAR or classic topographic data. Describing the content of data, metadata is a key component of data discovery in geo-portals. An inventory of seven online geo-portals and commercial catalogues shows that the metadata referring to 3D information is very different from one geo-portal to another as well as for similar 3D resources in the same geo-portal. The inventory considered 971 data resources affiliated with elevation. 51% of them were from three geo-portals running at Canadian federal and municipal levels whose metadata resources did not consider 3D model by any definition. Regarding the remaining 49% which refer to 3D models, different definition of terms and metadata were found, resulting in confusion and misinterpretation. The overall assessment of these geo-portals clearly shows that the provided metadata do not integrate specific and common information about 3D geospatial models. Accordingly, the main objective of this research is to improve 3D geospatial model discovery in geo-portals by adding a specific metadata-set. Based on the knowledge and current practices on 3D modeling, and 3D data acquisition and management, a set of metadata is proposed to increase its suitability for 3D geospatial models. This metadata-set enables the definition of genuine classes, fields, and code-lists for a 3D metadata profile. The main structure of the proposal contains 21 metadata classes. These classes are classified in three packages as General and Complementary on contextual and structural information, and Availability on the transition from storage to delivery format. The proposed metadata set is compared with Canadian Geospatial Data Infrastructure (CGDI) metadata which is an implementation of North American Profile of ISO-19115. The comparison analyzes the two metadata against three simulated scenarios about discovering needed 3D geo-spatial datasets. Considering specific metadata about 3D geospatial models, the proposed metadata-set has six additional classes on geometric dimension, level of detail, geometric modeling, topology, and appearance information. In addition classes on data acquisition, preparation, and modeling, and physical availability have been specialized for 3D geospatial models.
Highlights
1 http://www.freecadweb.org 2 http://www.sketchup.com 3 http://sketchup.google.com/3dwarehouse/buildingmaker 4 http://www.3dtin.com 5 https://tinkercad.com 6 From Harvard University’s city models, Google 3D model collections, and 3dcadbrowser, turbosquid, vizmod portals 7 Geographic Information System 8 Computer Aided Design 9 Computer Aided Manufacturing 10 Computer Generated Imagery internal contents
This paper presents an inventory conducted on metadata resources from eight online geo-portals and commercial catalogues where various 3D geospatial resources are published
As the first validation attempt, Canadian Geospatial Data Infrastructure (CGDI) Discovery Portal was selected for comparison since its metadata partially conforms to North American Profile (NAP) of International Organization for Standardization (ISO) 19115
Summary
1 http://www.freecadweb.org 2 http://www.sketchup.com 3 http://sketchup.google.com/3dwarehouse/buildingmaker 4 http://www.3dtin.com 5 https://tinkercad.com 6 From Harvard University’s city models, Google 3D model collections, and 3dcadbrowser, turbosquid, vizmod portals 7 Geographic Information System 8 Computer Aided Design 9 Computer Aided Manufacturing 10 Computer Generated Imagery internal contents. Dietze et al (2007) are closer to mass dissemination of 3D geospatial models by extending a generic metadata standard (i.e. ISO 19115). Their extension remains almost exclusive to city models and CityGML16. Mass dissemination of 3D geospatial models is not limited to specific domains with mutual repositories For this reason, this paper presents an inventory conducted on metadata resources from eight online geo-portals and commercial catalogues where various 3D geospatial resources are published. Current metadata requires additional information on internal specifications of 3D geospatial models.
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