NPSNET : hierarchical data structures for real-time three-dimensional visual simulation.

102 Pages·1.4 MB·en_US

by  Mackey, Randall Lee.;Zyda, Michael J.;Pratt, David R.

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NAVAL POSTGRADUATE SCHOOL
Monterey, California
THESIS
NPSNET: HIERARCHICAL DATA STRUCTURES
FOR REAL-TIME THREE-DIMENSIONAL
VISUAL SIMULATION
by
Randall Lee Mackey
September 1991
Thesis Co-Advisors: Michael J. Zyda
David R. Pratt
Approved for public release; distribution is unlimited.

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val Postgraduate School
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TITLE (IncludeSecurityClassification) NPSNET: HIERARCHICAL DATA STRUCTURES FOR REAL-TIME
THREE-DIMENSIONAL VISUAL SIMULATION
(U)
PERSONALAUTHOR(S)
Mackey, Randall Lee
TYMPaEstOeFrREsPTOhReTsi.s 13bF.RTOIMME C1OV1E/R90ED to 09/91 14S.eDpAtTEemObFeRrEP1O99R1T(Year, Month, Day) 1$ PAG9E1COUNT
supplementary notation" The views expressed in this thesis are those of the author and do not reflect the
icial policy or position of the Department ofDefense or the United States Government.
COSATI CODES 18. SUBJECTTERMS (Continueonreverseifnecessaryandidentifybyblocknumber)
ELD GROUP SUB-GROUP Computer Graphics, Simulators, Hierarchical Data Structures, Digital
Terrain Data
ABSTRACT (Continueonreverseifnecessaryandidentifybyblocknumber)
NPSNET is a low-cost visual simulation system designed and constructed at the Naval Postgraduate School.
'SNET uses digital terrain data and renders scenes involving vehicles, aircraft, cultural features, and natural
itures in real-time. The implementation of a terrain paging algorithm in NPSNET is discussed. Terrain paging
pands the terrain area available for simulation and overcomes the limits of main memory size. Hierarchical data
uctures commonly used in visual simulation systems are surveyed. The generation of a multi-resolution terrain
:aset and the implementation ofa hierarchical data structure are explained. The multi-resolution dataset is created
generating lower resolution descriptions of polygons from the original data. The hierarchical data structure used
NPSNET, based on quadtrees, provides a means to attenuate the resolution ofterrain over distance and cull those
rtions ofterrain outside ofthe user's field ofview.
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NPSNET: HIERARCHICAL DATA STRUCTURES
FOR REAL-TIME THREE-DIMENSIONAL
VISUAL SIMULATION
by
Randall Lee Mackey
Captain, United States Army
B.S., United States Military Academy, 1981
Submitted in partial fulfillment ofthe
requirements for the degree of
MASTER OF SCIENCE IN COMPUTER SCIENCE
from the
NAVAL POSTGRADUATE SCHOOL
September 1991
ABSTRACT
NPSNET is a low-cost visual simulation system designed and constructed at the
Naval Postgraduate School. NPSNET uses digital terrain data andrenders scenes involving
vehicles, aircraft, cultural features, and natural features in real-time. The implementation
of a terrain paging algorithm in NPSNET is discussed. Terrain paging expands the terrain
area available for simulation and overcomes the limits ofmain memory size. Hierarchical
data structures commonly used in visual simulation systems are surveyed. The generation
ofa multi-resolution terrain dataset and the implementation ofa hierarchical data structure
are explained. The multi-resolution dataset is created by generating lower resolution
descriptions of polygons from the original data. The hierarchical data structure used in
NPSNET, based on quadtrees, provides a means to attenuate the resolution of terrain over
distance and cull those portions ofterrain outside ofthe user's field ofview.
in
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TABLE OF CONTENTS
INTRODUCTION
I. 1
MOTIVATION
A.
1
FOCUS
B. 1
1. Expanding the Terrain Area for Simulation 2
2. Reducing Polygon Flow 2
C. SUMMARY OF CHAPTERS 4
HISTORY OF REAL-TIME VISUAL SIMULATORS AT NPS
II. 5
A. FOGM MISSILE SIMULATOR 5
1. Overview 5
2. Terrain Paging 7
3. Polygon Culling 7
B. VEH VEHICLE SIMULATOR 7
1. Overview 7
2. Terrain Paging 7
3. Polygon culling 8
MPS MOVING PLATFORM SIMULATORS
C. 9
1. Overview 9
2. Terrain Paging 10
3. Multiple Resolution 10
4. Polygon Culling 13
CCWF COMMAND AND CONTROL WORKSTATION
D.
OF THE FUTURE
13
1. Overview 13
IV