In: Wagner W., Székely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Vol. XXXVIII, Part 7B 
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A DBMS-BASED 3D TOPOLOGY MODEL FOR LASER RADAR SIMULATION 
C. Jun a ’*G. Kim a 
a Dept, of Geoinformatics, University of Seoul, Seoul, Korea - (cmjun, nani0809)@uos.ac.kr 
Commission VII 
KEY WORDS: Modelling, Simulation, Data Structures, Database, Laser scanning, Three-dimensional 
ABSTRACT: 
Developing LADAR(Laser radar) is viewed to be an important technology for next generation guided weapons in many countries. 
However, experiments using real guided weapons are not practical and we need computing environment that can simulate the 3D 
detections by LADAR. Such simulations require dealing with large sized data representing buildings and terrain over large area. 
They also need the information of 3D target objects, for example, material and echo rate of building walls. However, currently used 
3D models are mostly focused on visualization maintained as file-based formats and do not contain such semantic information. In 
this study, as a solution to these problems, a method to use a spatial DBMS and a 3D model suitable for LADAR simulation is 
suggested. The 3D models found in previous studies are developed to serve different purposes, thus, it is not easy to choose one 
among them which is optimized for LADAR simulations. In this study, 4 representative 3D models are defined, each of which is 
tested for different performance scenarios. As a result, one model, “BODY-FACE” structure, is selected as being the most suitable 
model for the simulation. A process to build a spatial DBMS and to compute and visualize with the proposed model was illustrated 
using a test area. 
1. INTRODUCTION 
LADAR(Laser radar), the 3D detection technology is 
increasingly getting attention as being the next generation 
guided weapons. Experiments using real guided weapons for the 
development of the LADAR would require tremendous amount 
of money. Therefore, we need computing environment that can 
simulate the 3D detections by LADAR. Such simulations 
require dealing with large sized data representing buildings and 
terrain over large area. They also need the information of 3D 
target objects, for example, material and echo rate of building 
walls. However, currently used 3D models are mostly focused 
on visualization and do not contain such semantic information. 
Modeling and visualizing terrains in 3D have been well known 
techniques now and most commercial GIS packages 
accommodate tools to represent terrain data types (i.e. TINs). 
However, modeling techniques for buildings in 3D have less 
been established and are still being studied theoretically without 
explicit implementations. Current techniques can be categorized 
into two—CAD and GIS. CAD systems, with diverse data types 
(e.g. cylinders, cones and freeform shapes), have been 
extensively used to model complex shapes in architecture or 
mechanics fields. On the other hand, GIS is mainly designed to 
represent geographical features and use less number of data 
primitives than CAD, which are points, lines and polygons. 
However, 3D representation provided by current commercial 
GIS packages is limited to 2.5D, which means that one location 
can have only one z value. Although both approaches have been 
used for years and suffice visualization purposes at certain 
application domains, still some issues remain to be resolved. 
Neither CAD nor GIS for 3D objects supports topological 
structure. Topology is the key property implemented in 2D GIS 
such as adjacency and connectivity that enables diverse analyses. 
* Corresponding author. 
We need such property in 3D buildings in order to define 
semantic information in urban models for LADAR simulations. 
LADAR simulations frequently deal with large areas and, thus, 
we need to represent a larger number of buildings than a few. 
Most CAD systems use file-based formats, which are 
unfavorable for storing and visualizing many building objects 
due to the computational performances. In contrast, although 
GIS packages support both file and DBMS formats, they are 
mostly software-dependent and do not support 3D topology as 
of now. 
A solution to these problems would be using DBMSs, which are 
widely accepted as reliable method for managing large amount 
of data. The purpose of this study is to compare DBMS-based 
3D models and suggest suitable ones that satisfy spatial 
operations and visualization for LADAR simulations while 
minimizing computation time. We first categorized 3D topology 
data models found in literature including our own model. Then 
we carried out performance tests for each of the models to test 
differences in retrieval times for visualization and range queries. 
The PostgreSQL/PostGIS was used for the tests. We also 
visualized the queried geometries using VRML and OpenGL. 
2. 3D MODELS 
2.1 3D models for building details 
Architecture may be the field that use 3D models most 
extensively. CAD-based models have been used widely for 
detailed 3D building modeling, and there is a growing interest 
in using IFC(Industry Foundation Classes) format for modeling 
and developing building information systems. Although these 
formats offer flexibility in modeling 3D objects with various 
data primitives, their file-based formats have limitations for