PostGIS meets the Third DimensionOlivier COURTIN - Jonathan DERROUGH Paris - June 2011

Presentation Plan Spatial Databases Standards and 3D

PostGIS 2.0 and 3D Implementation 3D GIS Open Source Stack Orbe 3D application use case Open Issues List

Perspectives and Conclusion

Oslandia SME Company

Expertise in OpenSource GIS.

Mainly Focus on:

- Spatial Databases - OGC/ISO Web Services

- Routing, Network and Graphs Solutions - QGIS

- OGC and OsGEO Member

OrbeSME Company

Expertise in interactive 3D applications

Mainly Focused on: - Media, user data & GIS integration with realtime 3D - Enabling users to create & share geolocated data across platforms - PC/Mac, desktop & web, smartphone applications

3D GIS: A meeting point BIM:

Focus on Building model

CAD/CAO world

IFC standard

CIM: Focus on City model

GIS world

CityGML standard

CIM: Focus on City model

GIS world

CityGML standard

First Implementation

First implementation of 3D in PostGIS: 2007 (PoC)(FOSS4G 2007)

A bit too early:- No available and stable client to render 3D on a browser- 3D data were still expensives- Market not mature enough

Spatial database standards: 3D concepts

OGC SFS 1.2.02006

ISO 19125Draft 2011

ISO 191252004

ISO SQL/MM2003

OGC SFS 1.11999

ISO SQL/MM2006

ISO SQL/MMDraft 2009

ISO TC 211

OGC SFS WG

ISO JTC1 SC32 WG4

New Surface types: TriangleOne exterior ring with 3 differents points

(and 1 point more to close the ring)

No interior ring (i.e no hole)

Points must not be colinears

Triangle could be 2D, 3D, 3DM or even 4D

TRIANGLE((0 2, 10 4, 12 0, 0 2))

New Surface types: TINCollection of triangles connected by edges

Every triangle share same orientation

TIN could enclose a solid (or not)

TIN could be 2D, 3D, 3DM or even 4D

TIN(((0 2, 10 4, 12 0, 0 2)), ((0 2, -2 -6, 12 0, 0 2)), ((0 2, 10 4, 5 8, 0 2)))

New Surface types: PolyhedralSurfaceCollection of polygons connected by edges

Every polygon share same orientation

Points of the polygon must be coplanar (enough)

Polygons could have internal rings (i.e holes)

PolyhedralSurface could enclose a solid (or not)

PolyhedralSurface could be 2D, 3D, 3DM or even 4D

POLYHEDRALSURFACE( ((0 2, 10 4, 12 0, 5 8, 0 2)), ((0 2, -2 -6, 12 -6, 12 0, 0 2)))

New Surface types: PolyhedralSurface

POLYHEDRALSURFACE(((0 0 0, 0 0 1, 0 1 1, 0 1 0, 0 0 0)),((0 0 0, 0 1 0, 1 1 0, 1 0 0, 0 0 0)),((0 0 0, 1 0 0, 1 0 1, 0 0 1, 0 0 0)),((1 1 0, 1 1 1, 1 0 1, 1 0 0, 1 1 0)),((0 1 0, 0 1 1, 1 1 1, 1 1 0, 0 1 0)),((0 0 1, 1 0 1, 1 1 1, 0 1 1, 0 0 1)))

s

A 3D PolyhedralSurface example, enclosing a cube

Spatial database standards: 3D specs

OGC SFS 1.2

2006

Draft ISO SQL/MM

2009

Draft ISO 191252011

Triangle No Yes YesTIN Yes Yes YesPolyhedralSurface Yes Yes YesFunctions on TIN and PolyhedralSurface handling

Yes Yes Yes

Functions on 3D Topology and measures (Distance, Intersects...)

No Yes Yes

Vertical Datum No No Yes

3D Functions Availables on TrunkBox2DBox3DGeometryTypeST_AffineST_AreaST_AsBinaryST_AsEWKTST_AsEWKBST_AsGMLST_AsX3D ST_DimensionST_DumpST_DumpPointsST_ExpandST_ExtentST_Extent3DST_FlipCoordinate

ST_Force_2DST_Force_3DST_Force_3DZST_GeomFromEWKTST_GeomFromEWKBST_GeomFromGMLST_GeometryNST_GeometryTypeST_IsClosedST_MemSizeST_NumGeometriesST_NumPatchesST_PatchNST_PerimeterST_Perimeter3DST_RotateST_RotateXST_RotateYST_RotateZST_ScaleST_Shift_LongitudeST_Transform

So what available in PostGIS 2.0, for 3D ?

OGC SFS 1.2 3D Types (TIN, PS)

3D spatial indexes

GML and X3D geometries

Input / Output

That's the really basics, and should initiate new usages (and so we hope fundings)

(Really) BasicSpatial Analysis

Common 2D GIS Architecture

Spatial Database

Webclient

Desktop client

Data loader

Web Services

What do we want for 3D Architecture ?

Spatial Database

Webclient

Desktop client

Data loader

Web Services

Well, the same than for 2D !

3D GIS Architecture

Collada loader

Spatial Database

WFS -T

W3DS

Web 3Dclient

Desktop 3D client

CityGML loader

3D GIS Architecture: CityGML loader

Collada loader

Spatial Database

WFS -T

W3DS

WebGLclient

Desktop 3D client

CityGML loader

BRGM provide a C++ beta CityGML parser lib (libcitygml)But still no tool to perform a CityGML to PostGIS import.

3D GIS Architecture: Collada Loader

Collada loader

Spatial Database

WFS -T

W3DS

Web 3Dclient

Desktop 3D client

CityGML loader

Collada-dom provide a C++ API on collada docsBut still no tool to import Collada inside PostGIS

3D SIG Architecture

Collada loader

Spatial Database

WFS -T

W3DS

Web 3Dclient

Desktop 3D client

CityGML loader

TinyOWS is already able to output and input GML 3.1.1But not yet CityGML (or broader Application Schema)

3D SIG Open Source Architecture

Collada loader

Spatial Database

WFS -T

W3DS

Web 3Dclient

Desktop 3D client

CityGML loader

AFAIK still no Open Source application for W3DS implementation, other than Proof Of Concept

3D SIG Open Source Architecture

Collada loader

Spatial Database

WFS -T

W3DS

Web 3Dclient

Desktop 3D client

CityGML loader

Alpha of globe support in QGIS multithreaded branchNext step: having something stable and volumes handling

3D SIG Open Source Architecture

Collada loader

Spatial Database

WFS -T

W3DS

Web 3Dclient

Desktop 3D client

CityGML loader

Beta of globe support with OpenWebGlobe (WebGL)Next step: having something stable and volumes support.

Current ORBE X3D implementation Observations: - 3D is cheaper than 2D! As far as maps are concerned (in our own use cases), 3D files are far more light-weighted than their rasterized counterparts - 3D objects can be used at a wider range of zoom levels without quality loss than 2D rasters

Current ORBE X3D implementation Former approach: - use a 2D map to build 3D « by hand », ideal for small areas and without access to GIS data

Current approach: - export GIS data in a (hopefully soon) widely supported 3D file format like X3D

- for that purpose, Orbe created a PostGIS 2.0 function using Jonathan Schewchuk's Triangle for triangulation: ST_AsX3D

Open Issues Lists1) Triangulation 2) TIN Simplification3) CityGML Loader 4) IsValid geometries check5) Vertical Datum6) TIN for DEM Storage7) Texture handling8) 3D Topology functions

Open Issue #1: Triangulation Lot of 3D usages only deal with TIN and not with PolyhedralSurface

So be able to convert PolyhedralSurface to TIN will become a need

Known Implementations: CGAL, TetGen

Open Issue #2: Tin Simplification

Reduce the number of triangles

Preserve the volume

Preserve the global andlocal shapes

Known Implementations: CGAL, GTS

Fast and memory efficient Algorithm: Lindstrom and Turk

Source: CGAL

Open Issue #3: CityGML LoaderGML 3 handles a lots of geometry types that spatial database standard don't. (true solid...)

GML allow composition of several solids into a single feature

Interesting to be able to downsize LOD(e.g: LOD 3 -> LOD 2)

CityGML extension application schema (ADE)

Implies Triangulation and simplification to import TIN into database and 3D ST_Union

Open Issue #4 IsValid CheckIsValid checks are currently done by GEOSGEOS don't care about Z dimension nor 3D types

No Self Intersection

All Faces edges connected

All Faces Well Oriented

Points of face are coplanars

Open Issue #5: Vertical DatumSRID is used to reference a Coordinate Reference System

Proj4 begins to add vertical datum support,But not yet handle alls.

Proj4 begins to add vertical datum support,But not yet handle alls.

Open Issues #6 DEM storage

Terrain DEM model use also often TIN structure

But it's a NONSENSE to store a whole DEM in a single PostGIS TIN feature !

To store efficiently: - Ability to split the whole TIN into smaller pieces

- Store each pieces in a different PostgreSQL row

- Spatial index to access quickly to each piece

Source: NASA

Open Issue #7 Texture

A Texture is composed of:

A 2D geometry (UV)

Associated to an image

Explore the ability to deal with texture handling throught PostGIS Raster ?

Open Issue #8 Topology Operations

(source Zlatanova, Rahman and Shi 2002)

Now Topology operations are done by GEOS

GEOS (and JTS) only handle 2D (OGC SFS 1.1)

3D Topology Operations only appear in latest SQL/MM and ISO 19125 drafts

There's a need for a robust C++ Topology lib able to fully handle ISO 19107 (2D and 3D).

Conclusions

PostGIS 2.0 will be able to deal with 3D geometries primitives and some very basic spatial functions

A full 3D support in PostGIS (textures, TIN, LOD) means lot of work and will require related funding.

3D Topology library is a broader issue than only PostGIS concern, and should be shared by others Open Source apps.

3D Open Source stack could/should arrive in a quite near future, as each piece becoming more stable and used.

Conclusions

PostGIS 2.0 will be able to deal with 3D geometries primitives and some very basic spatial functions

A full 3D support in PostGIS (textures, TIN, LOD) means lot of work and will require related funding.

3D Topology library is a broader issue than only PostGIS concern, and should be shared by others Open Source apps.

3D Open Source stack could/should arrive in a quite near future, as each piece becoming more stable and used.

Conclusions

PostGIS 2.0 will be able to deal with 3D geometries primitives and some very basic spatial functions

A full 3D support in PostGIS (textures, TIN, LOD) means lot of work and will require related funding.

3D Topology library is a broader issue than only PostGIS concern, and should be shared by others Open Source apps.

3D Open Source stack could/should arrive in a quite near future, as each piece becoming more stable and used.

Conclusions

PostGIS 2.0 will be able to deal with 3D geometries primitives and some very basic spatial functions

A full 3D support in PostGIS (textures, TIN, LOD) means lot of work and will require related funding.

3D Topology library is a broader issue than only PostGIS concern, and should be shared by others Open Source apps.

3D Open Source stack could/should arrive in a quite near future, as each piece becoming more stable and used.

Conclusions

PostGIS 2.0 will be able to deal with 3D geometries primitives and some very basic spatial functions

A full 3D support in PostGIS (textures, TIN, LOD) means lot of work and will require related funding.

3D Topology library is a broader issue than only PostGIS concern, and should be shared by others Open Source apps.

3D Open Source stack could/should arrive in a quite near future, as each piece becoming more stable and used.

Contacts

Olivier COURTINolivier.courtin@oslandia.com

www.oslandia.com

Jonathan DERROUGHj.derrough@orbe.mobi

www.orbe.mobi