Geoscience Reference
In-Depth Information
Table 3 Analyses of the second question of scenario 1 (comparison between the proposed 3D
metadata and CGDI discovery p ortal)
Analyses
Question
What is the corresponding LoD of the building dataset?
The proposed 3D metadata
CGDI discovery portal
Explicit?
Ye s
No
Conceptual integrity/limits • Addresses various aspects of data 
granularity
- Geometric / Thematic / Graphic /
Combined
• Regards several metadata indicators
- primitive count / voxel size / point
density
• Permits proprietary LoD definitions
• No indication about 
LoD
Syntactic integrity/limits
•  Level of Details class aggregates
several explicit association classes
- LOD GDS / LOD Geom Count / LoD
Particular … classes (Fig. 3 )
N/A
Table 4 Analyses of the question of scenario 2 (comparison between the proposed 3D metadata
and CGDI discovery portal)
Analyses
Question
What is (or are) the vertical reference(s) of the dataset(s)?
The proposed 3D metadata
CGDI discovery portal
Explicit?
Ye s
Ye s
Conceptual integrity/limits • Three types of vertical references
- mean sea level/geodetic ellipsoid/
proprietary (auxiliary)
• Auxiliary vertical references can 
hold any type of geometry
- anchor point, polyline, …
• Two types of vertical 
references
- mean sea level/average
ground level
• Do not considers auxiliary 
vertical references
Syntactic integrity/limits • Multiplicity allowed
• Enumerated  Type and Geometry ,
and fee-text Identification Name
properties of Vertical Geospatial
Reference class
• Single multiplicity
• Enumerated  Vertical
Datum Type and fee-text
Datum Name properties
datum, auxiliary vertical references like street axis/surfaces in vertical profiles and
cross-sections, relative vertical offsets, and etc.). Therefore, this scenario expresses
this exigency with the following question:
• What is (or are) the vertical reference(s) of the dataset(s)? (analyses in Table 4 )
Scenario 3: Seeking 3D Datasets According to Specific 3D Modeling Environments
Five of the eight inventoried portals advocate specific software environments (i.e.
GoCAD, SketchUp, ESRI ArcGIS, Autodesk CAD software family). Besides,
Google Trends ( http://www.google.ca/trends ) indicates “autodesk”, “3d max”,
“maya”, “sketchup”, and “blender” among the top and rising terms which are
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