Experience: From Validation to Database Management Kean Huat SOON, Eric LOW, Zhen Hao NG and Victor KHOO
Outline : WOG 3D National Topographic Mapping Project Validation Process Management of Data in DBMS Outlook ()
WOG 3D National Topographic Mapping Project Two Phases: Phase 1 Airborne; Phase 2 Mobile, for the whole Singapore @Phase 1: Modeling for Relief, Waterbody, Vegetation, Bridge and Building (LOD0-LOD2) @Phase 2: City Furniture, Relief, Tunnel and Transportation (LOD0-LOD2) To develop a national 3D topographic database, which is based on 2.0 schema
Open Geospatial Consortium (OGC) encoding standard since 2008 developed by international experts Open standard XML-based not confined by proprietary software, i.e. neutral machine readable and processable can be opened in any Operation Systems (MacOS, Windows, Linux,etc)
2.0 Thematic Modules Application Domain Extensions (ADE) Generics Appearance Building Bridge CityFurniture CityObjectGroup LandUse Relief Transportation Tunnel Vegetation WaterBody Core / GML 3.1.1 (Source: Claus Nagel)
LOD 0 to LOD 4 LOD 0 only FootPrint and/or RoofEdge LOD 1 Block model w/o roof structures 6 LOD 2 Differentiated roof structures, building installations LOD 3 Detailed architecture model LOD 4 LOD 3 + model of the interior space (Source: OGC) (Source: TUDelft)
Data Management Building Model CityObject Abstract Building Building roof surface Building Part Boundary Surface Roof Surface Wall Surface wall surface ground surface 3D Geometry + Topology + Semantics + Appearance
Data Management Building Model CityObject Abstract Building Building roof surface Building Part Boundary Surface Roof Surface Wall Surface wall surface ground surface 3D Geometry + Topology + Semantics + Appearance
as DB Schema
as Exchange Format
Singapore Building LOD 2 Singapore s Spatial Reference System in 3D A unique GML ID for 3D Buildings Singapore Localized Codelists Address
Spatio-Semantic Coherence critical for complex queries, analysis and simulations Geometry objects know WHAT they are CityObject Abstract Building Building Building Part Boundary Surface Roof Surface Wall Surface Semantic objects know WHERE they are and their spatial extent 11
Applications Development Planning Rainwater Runoff Assessment Green Applications Flood modeling Building Height Study Solar Potential Study Telecommunication Coverage Climate Change Study Pollution Dispersion, etc. 12 Data Management (Source: CyberCity3D)
Analysis and simulation results are not reliable if the quality of the models is not ensured. have been carried out to check schema (e.g. compliance and external reference) themes (e.g. Building, Bridge) geometries (polygon and solid) semantics (e.g. wall surface, roof surface) database import (e.g. data type) Using validation tools FZK Viewer 3D CityDB Importer/Exporter v3.0 CityDoctor 13
Validation Process Models validate accept produce Validation Tools reject Quality Checks (SLA) 3D Topography DB (SLA) communicate Modelers (Vendors) 14 Discussions/Requirements (SLA and vendors)
Validation Process Models validate accept produce Validation Tools reject Quality Checks (SLA) 3D Topography DB (SLA) communicate Modelers (Vendors) 14 Discussions/Requirements (SLA and vendors)
FZK Viewer Visual and manual attribute checks include gml id, codelists, etc. e.g. address, external reference, measuredheight roof type Building? e.g. volume, surface area 15
3D CityDB Importer/Exporter 3.0 Fully automated Schema checks for all thematic modules (e.g. Building, Relief, Bridge) Database import check Includes other functionalities e.g. import and export from database http://www.3dcitydb.net/
CityDoctor Validation Tool Content in tree structure Four different views Color Preference Validation Criteria Geometric Table http://citydoctor.hft- stuttgart.de Validation Results Panel Validation Results in XML
CityDoctor Polygon Checks Solid Checks Semantic Checks Additional Checks Building models are validated automatically through Polygon Checks, Solid Checks, and Semantic Checks. Currently the tool is limited to Building only 18
Polygon Checks 1. A linear ring must consist of a minimum of 4 points 2. First and last point of a linear ring are identical. 3. All points of a linear ring are different, with exception of first and last point. 4. Two edges can intersect only in one start- /end point. Other points of intersection or touching are not allowed (to account for rounding errors or polygons which are not perfectly planar, a small tolerance is allowed). 5. All points of the polygon must be located in a plane (a small tolerance is allowed). X X X X X X 19 (Source: Alam et. al 2013)
Solid Checks X X 1. The minimum number of polygons to define a solid is four. They must be situated in different planes. 2. A valid intersection of two polygons of a solid either contains a common edge, a common point of a linear ring, or is empty. Common edges and points must be elements of both polygons. 3. Each edge of a linear ring defining a polygon is used by exactly one neighboring polygon. 4. Consistent orientation of polygons of a solid such that common edges according to check 4 are used in opposite direction. 5. The normal vectors of the polygons must point towards the outside of the solid. 6. All parts of a solid must be connected. X X (Source: Alam et. al 2013) 20
Semantic Checks 1. Orientation of RoofSurface, WallSurface and GroundSurface elements 2. measuredheight in same range as height of building geometry 3. numberofstoreysaboveground plausible for height of the building geometry 4. numberofstoreysbelowground plausible for height of underground geometry of the building 5. Relationship of Building and BuilidingPart (Source: Alam et. al 2013) 21
Loading Content to DBMS All faces of building Roof Wall Files <gml:solid gml:id="srf_t29i1172_2543" > <gml:exterior> <gml:compositesurface >. </gml:compositesurface> </gml:exterior> </gml:solid> <gml:surfacemember> <gml:polygon gml:id= poly_t29i1172_p2543_0"> <gml:exterior> <gml:linearring gml:id="line_t29i1172_p2543_0"> <gml:poslist srsdimension="3">. </gml:poslist>.. </gml:surfacemember> <gml:surfacemember> <gml:polygon gml:id= poly_t29i1172_p2543_1"> <gml:exterior> <gml:linearring gml:id="line_t29i1172_p2543_0"> <gml:poslist srsdimension="3">. </gml:poslist>.. </gml:surfacemember> SURFACE_GEOMETRY ID GMLID PARENT_ ID ROOT _ID Database IS_SOLID IS_COMPOSITE GEOMETRY SOLID_GEOMETRY 1 srf_t29i1172_2543 (null) 1 1 0 (null) SDO_GEOMETRY 2 UUID 1 1 0 1 (null) (null) 3 poly_t29i1172_p2543_0 2 1 0 0 SDO_GEOMETRY (null) Building Wall Wall <gml:surfacemember> <gml:polygon gml:id= poly_t29i1172_p2543_2"> <gml:exterior> <gml:linearring gml:id="line_t29i1172_p2543_0"> <gml:poslist srsdimension="3">. </gml:poslist>.. </gml:surfacemember> <gml:surfacemember> <gml:polygon gml:id= poly_t29i1172_p2543_3 "> <gml:exterior> <gml:linearring gml:id="line_t29i1172_p2543_0"> <gml:poslist srsdimension="3">. </gml:poslist>.. </gml:surfacemember> 3D City DB Importer/ Exporter 4 poly_t29i1172_p2543_1 2 1 0 0 SDO_GEOMETRY (null) 5 poly_t29i1172_p2543_2 2 1 0 0 SDO_GEOMETRY (null) 6 poly_t29i1172_p2543_3 2 1 0 0 SDO_GEOMETRY (null) 7 poly_t29i1172_p2543_4 2 1 0 0 SDO_GEOMETRY (null) Wall <gml:surfacemember> <gml:polygon gml:id= poly_t29i1172_p2543_4"> <gml:exterior> <gml:linearring gml:id="line_t29i1172_p2543_0"> <gml:poslist srsdimension="3">. </gml:poslist>.. </gml:surfacemember> 22
From DBMS to More Files 3D CityDB Importer/ Exporter Single Source of Truth GIS Data (e.g. ESRI, Bentley, etc.) Web Feature Services, KML, COLLADA, etc. Interfacing 23
Principle Single Source of Truth using Oracle Spatial Data integrity (e.g. no duplicates, always up- to- date) Database Management System (DBMS) vs File- based Management Centrally managed while sharing through web services (SOA) 24
Maintenance with GIS software? Maintaining with multiple SDO_GEOMETRY columns is a challenge for any GIS software Currently working with Bentley Technical Team to tackle the challenge Multiple SDO_GEOMETRY columns 25 3D City Database Schema
Outlook () Building modeling is still work in progress, expected to complete by year end Final models are not aimed at 100% error proof, but hopefully at 85%. Main reason due to the complexity of the buildings, especially in CBD 26
Outlook Looking at more elegant way of maintaining the database using GIS software as opposed to export and import files for every update CityDoctor would be great to consider other thematic modules (e.g. Transportation) 27
Acknowledgement Appreciate the technical supports given by (alphabetical order): 3D City DB Team from virtualcitysystems (Nagel, Kunde) AAM (Lambert) Bentley Technical Team (Rao) CityDoctor Team from HFT Stuttgart (Coors, Alam) 28
thank you! {soon_kean_huat@sla.gov.sg; eric_low@sla.gov.sg; ng_zhen_hao@sla.gov.sg; victor_khoo@sla.gov.sg} 29