THE USE OF SIMULATION TO TEACH AERIAL TRIANGULATION WITH GPS AND 
IMU MEASUREMENTS 
D.W.G. Park, M.J. Smith 
IESSG, University of Nottingham, University Park, Nottingham, NG7 2RD, UK 
david.park@nottingham.ac.uk 
Commission VI, WG 2 
KEY WORDS: Photogrammetry, Education, Simulation, Teaching, Triangulation, Bundle, GPS/INS 
ABSTRACT: 
The Institute of Engineering Surveying and Space Geodesy (IESSG) at the University of Nottingham, UK has developed a number 
of simulators which have been used on a number of commercial and research projects. They are also playing an ever greater role as 
teaching tools at undergraduate and masters level. This paper presents some of the key packages developed and used by the IESSG 
over the last 10 years as well as a more detailed explanation about our more recent aerial triangulation / in-flight GPS/IMU simulator 
(including examples and student results). 
1. INTRODUCTION 
For many years the Institute of Engineering Surveying and 
Space Geodesy (IESSG) at the University of Nottingham has 
been using simulators of various kinds in its research activities. 
There are many advantages of using simulators. Simulated data 
can provide early opportunities for researching new equipment 
or procedures. The analysis through simulation of a potential 
measurement process can provide confidence before full 
commitment is made to invest. Simulators can enable a new 
computational technique to be assessed with controlled error 
budgets enabling the testing and optimising of new algorithms. 
The IESSG is also aware of the exciting uses and powerful 
benefits that simulators can bring to teaching. Simulators can 
develop skills and knowledge of the processes as well as an 
appreciation of the quality of the process and results that can be 
achieved. 
In October 2001 the IESSG started a new MSc course in 
Satellite Positioning Technology. As part of this course we 
have a module on integrated systems. For sometime, we have 
been researching the use of GPS and IMU measurements 
integrated with aerial photography and line scanner imagery. 
This provides us with an excellent example of how sensors can 
be successfully integrated. We therefore decided that the 
students learning experience would be considerably enhanced if 
they could work with a simulator to investigate different 
photographic scenarios and different qualities of GPS and IMU. 
In the new academic session the simulator has provided a new 
and exciting approach to teaching. 
In this paper we present case studies exploring two of our 
current research driven simulators (Section 2.1) and two of our 
existing teaching-related simulators (Section 2.2). Section 3.1 
then introduces our new simulation suite designed to aid in the 
teaching of acrial triangulation (both traditional and including 
the input from a range of GPS/IMU sensors) with actual results 
from undergraduate, Masters and Doctoral students presented in 
Section 3.2 Section 4 summarises our findings and conclusions. 
2. EXISTING SIMULATION FACILITIES 
2.1  Research-driven Simulation at IESSG 
The IESSG already utilises a range of software simulation 
within its varied research portfolio. Some of these have been 
developed in-house by successive Masters and Doctoral level 
students, others have been initiated by contract research from 
industry or institutions such as the European Space Agency. In 
this section, case studies are presented of just two of our 
simulators, the ESA funded GalileoSat simulator facility and 
the BNSC funded integrated GPS-Galileo-Communications 
facility (FURLONG) 
The GalileoSat System Simulation Facility (GSSF) project is 
a contract funded by the European Space Agency (ESA) to 
produce an end-to-end software simulation of Europe's planned 
'Galileo' satellite navigation system. It will model all of the 
components of the future system, from the satellites themselves, 
to the ground segment that will control them and the user 
receivers that will navigate with their signals. 
As part of the VEGA-led team working on the study, the IESSG 
is acting as a consultant on technical aspects of satellite 
navigation and specific modelling details. The IESSG's role is 
to provide definitions of suitable simulation and modelling 
algorithms, with the necessary algorithm description, sample 
source code where necessary, and test data. The IESSG is also 
responsible for the validation of the software, which will 
provide the necessary proof that GSSF produces the correct 
results. 
One of the future aims of GSSF is to be able to replace software 
components of the system with real hardware - a so-called 
hardware-in-the-loop design. For instance, early versions of 
GSSF will simulate a Galileo user receiver in software, but later 
versions may wish to replace the software receiver with a 
prototype hardware version. This requires that the simulation 
models are as true to life as can practicably be achieved. The