Recently, several open-source software tools such as CesiumJS and iTowns have been developed for dealing with 3-dimensional spatial data. These tools mainly focus on visualization of 3D spatial data based on WebGL. An open-sourced server capable of storing, sharing and querying 3D spatial data has not yet been developed. GeoServer, one of the representative open source spatial data servers, provides many powerful features. In particular, it supports connecting to and publishing spatial data from a variety of data sources. GeoServer also supports Web Feature Service(WFS), which is a standard protocol established by the Open Geospatial Consortium to request geospatial feature data. However, GeoServer provides functions only for two- dimensional geometry, so it provides few functions for handling 3D spatial data. Because JTS Topology Suite, which is an important component of GeoServer, does not support 3D spatial operations, it also does not support solid geometries. In this paper, we discuss extension modules of GeoServer that we have implemented to handle 3D spatial data. First, instead of JTS, our modules adopted a geometry model based on the ISO 19107 standard and support 3D spatial operations from the Simple Feature CGAL library. Based on this geometry model, we have implemented new internal data structures that represent spatial information from the Feature interface in GeoServer. Second, we also extended the DataStore module to handle and store 3D spatial information for several data sources such as GeoJSON, GML and PostGIS. Finally, we extended the WFS module to share 3D spatial data via GeoServer.

1. Development of an extension
of GeoServer for handling
3D spatial data
Hyung-Gyu Ryoo (hgryoo@pnu.edu)
Soojin Kim (soojin.kim@pnu.edu)
Joonseok Kim (joonseok@pnu.edu)
Ki-Joune Li (lik@pnu.edu)
Pusan National University, South Korea
FOSS4G 2017 Boston - August 18, 2017
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2. FOSS4G 2017 Boston
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About Us
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Main Developers AdvisorInitial Design
Hyung-Gyu Ryoo
(hgryoo@pnu.edu)
Soojin Kim
(soojin.kim@pnu.edu)
Dr. Joonseok Kim
(joonseok@pnu.edu)
Prof. Ki-Joune Li
(lik@pnu.edu)

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NOTICE
This project is not be perfect
This project is a new challenge
Your insights and feedback
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Contents
● Why do we need GeoServer 3D?
● GeoServer/GeoTools 3D
● Demonstration
● Next Steps
● Summary
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Common Open Source 2D GIS Architecture
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Spatial
Databases
File
Sources
Geospatial
Server
Desktop
Client
Web
Client
PostGIS
OpenLayers
QGIS
GeoServer
ESRI Shapefile

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Why we need Geospatial server?
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Spatial
Databases
File
Sources
Desktop
Client
Web
Client
My Super
Server
My Super
Server2
My Super
Server3
My Super
Server4

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Common Open Source 2D GIS Architecture
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Spatial
Databases
File
Sources
Geospatial
Server
Desktop
Client
Web
Client
PostGIS
OpenLayers
QGIS
GeoServer
ESRI Shapefile

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Open source 3D GIS data visualization tools
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(cesiumjs.org) (itowns-project.org)
NASA World Wind
(worldwind.arc.nasa.gov)

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SFCGAL
Data Stores Supporting 3D
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(postgis.net)
(oracle.com/database/spatial/)
(sfcgal.org)

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For Open Source 3D GIS Architecture?
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Spatial
Databases
File
Sources
Geospatial
Server
Desktop
Client
Web
Client

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Existing Open Source 3D GIS Stack
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(3dcitydb.org)
?

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Requirements of a general 3D spatial data server
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1.Data structures to store features with 3D geometries
2.Functions to process queries on 3D objects
3.Connections to data stores able to store 3D spatial
information
4.Standard web services for sharing 3D spatial information

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For Open Source 3D GIS Architecture?
Spatial
Databases
File
Sources
Desktop
Client
Web
Client
?
GeoServer 3D
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● Representative open source spatial data servers
● Based on GeoTools
● Provide a variety of spatial data sources by excellent
abstraction
● Geospatial web services that provides functions to share
and query spatial data (OGC - WMS, WFS and WPS).
(geotools.org)(geoserver.org)About GeoServer

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Excellent Abstraction
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FeatureSource
DataStore
Data Type
Query
Feature Feature
Type
Filter
Function
Expression
WFS

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GeoServer has limitations in handling 3D!
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GeoServer can handle and store points, curves and surfaces
with z coordinates
But!
It is impossible to store spatial information with solids
Spatial query processing is performed without z coordinates
Why?

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JTS - limitation for supporting 3D in GeoServer
● JTS geometries can carry a Z coordinate
● What about solid geometries?
● What about 3D spatial operations?
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OGC::Simple Feature Access
based on
<Java Class>
JTS::Geometry

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ISO 19107 spatial schema-based interface
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<Java Interface>
ISO 19107 Spatial Schema
<Java Class>
ISO 19107 Geometries
Implementation
gt-geometry
● Implementations of ISO Geometry supported as an
unsupported module
● 3D spatial operations are not implemented

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We had two options!
● Options
○ Develop or port every function from scratch
○ Reuse or utilize existing open source libraries
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● Existing open source library for 3D spatial operations
○ CGAL (GNU LGPL 3+, GNU GPL 3+)
■ C++, A variety of robust computational geometry algorithms in 3D
spaces as well as 2D
■ Different from those in GIS domains
○ Simple Feature CGAL (GNU LGPL 2+) by Oslandia
■ C++, Based on CGAL and Boost

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<Java>
GeoServer
ISO Geometry
Geometry
DirectPosition
Point
Curve
...
Connecting SFCGAL to ISO Geometry module
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<C++>
SFCGAL
Geometry
Algorithm
CGAL
Boost
SFCGAL
Converter
JavaCPP
SFCGAL
Java Wrapper
Geometry
Algorithm

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Example of performing 3D operations
using SFCGAL
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Ex) Intersects between Curve and Solid
<ISO 19107>
Curve
<ISO 19107>
Solid
<SFCGAL>
SFLineString
<SFCGAL>
SFSolid
<SFCGAL>
IntersectsOperation
true/false

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New ISO 19107 Geometry Module
● Easy installation for Ubuntu users
○ sudo ./cppbuild.sh //Boost, CGAL and SFCGAL are installed
○ mvn clean install
● Support 3D operations
○ distance, area, volume, convexHull...
○ intersects, contains, within...
○ intersection, difference, union...
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Now, Done?
Absolutely
Not!
Long way to go...
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Next?
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Examine GeoTools/GeoServer from bottom to top
WFS

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Codes are coupled with JTS!
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Simple strategy
1.Use a well-defined interfaces in GeoServer/GeoTools
2.Copy and rewrite classes to support ISO 19107 geometries
if the class is connected to a JTS geometries
3.Leave codes that are not coupled with JTS as much as
possible
4.For copied codes, perform unit tests
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A Data Store for 3D Spatial Information
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● File data store
○ CSV
○ GeoJSON
○ GML
● Database data store
○ PostGIS
○ Oracle

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A Data Store for 3D Spatial Information
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Apply the 3D filter condition
using the SFCGAL operation
Candidate
features
Select features
without a 3D filter condition
Result
features
Select features
with a 3D filter condition
supported by data store
Y
N
Get Features
with a 3D spatial filter
Can the filter be supported in data store?
END

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WFS Extension for 3D Queries
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● Web Feature Service (WFS)
○ An interface for providing spatial data in vector format
○ WFS 1.1 supports GML 3.1.1 used in HTTP requests from and responses
to the client
○ the GML 3.1.1 contains solids element
● Encoding/Decoding of GML Elements contained in 3D filter
conditions.

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WFS Extension for 3D Queries
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Data Store
WFS Request/Response
Data
Feature
Collection
GML ⇔ Features with ISO Geometry
Filter
GeoServer
WFS Client
Data store
Query region

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3D Open Source Software Stack GeoServer
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DBMS/File
GeoTools
GeoServer
Services/Applications
OS
Cesium/NASA World Wind/QGIS
Ubuntu/CentOS
Oracle/PostGIS
FeatureStore
(Well defined)
GML/ShapeFile...
I/O Plugins
[GeoJSON, ShapeFIle…]
DataStores
[JDBCDataStore/FileDataStore]
Query/Filter
(JTS Only)
WPS Process
(JTS Only)
SQLDialect
Data Management
[Vector, DB]
Services
[WFS, WCS, WPS, WMS]
Web Administration
UI
Oracle
PostGIS
SFCGAL Extension
New DataStores
(uses ISO Geometry)
New SQLDialect, I/O Plugin
(type mapping to ISO Geometry)
New FilterFactory,
(uses SFCGAL query evaluation)
WPS Process
(new proc using ISO geometry)
GeoServer 3D Extension
XML Binidng
(JTS Only)
XML Binding
(uses ISO geometry)
WFS 1.1 Service
(uses ISO geometry)

33. Demonstration
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Demonstration(1/3) - Overview
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GeoServer 3D
Draw
WFS
Request
PostGIS 3D
WFS Client
Highlighting
WFS
Response
RegisterStore

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Demonstration(2/3) - Test Data
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● Test data 1 - Extruded Buildings from OSM data
○ Buildings with height over 3m in Boston
○ 39712 number of buildings
○ Each building is made of solid geometry.

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Demonstration(3/3) - Test Data
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● Test data 2 - Indoor data with 3D rooms from IndoorGML data
○ Rooms and corridors in a shopping mall in Seoul.
○ 3496 number of rooms
○ Each room is made of solid geometry.

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Next Steps
● Documentation!
● Administration GUI for 3D
● Making a switch between JTS and ISO Geometry
● Supporting WFS 2.0 version to support rich set of
advanced functions
● Plain WFS => Tiling
● Test and improve again and again to be stable
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OGC Visualization Model
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Data
Repository
Select
Display
Element
Generator
Render
Display
Internet
Thin
Server
(WFS)
Thick
Client
Data
Repository
Select
Display
Element
Generator
Internet
Data
Repository
Select
Display
Element
Generator
InternetRender
Display
Render
Display
Medium
Client
Medium
Server
(W3DS)
Thick
Server
Thin
Client

39. FOSS4G 2017 Boston
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Summary
● GeoServer does not support 3D spatial data handling
because it has been implemented based on Simple Feature
Access Specification
● We developed new implementation of ISO 19107 geometric
model, which can support 3D spatial geometry and
computation
● We extended lots of modules to support 3D functionalities
based on the geometric model
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Thank you!
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hgryoo@pnu.edu | @hgryoo
https://github.com/STEMLab/geotools-3d-extension
https://github.com/STEMLab/geoserver-3d-extension