International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B6. Istanbul 2004 
  
Several B.Sc. and M.Sc. final projects and thesis involving 
Digital Photogrammetry were carried out during the last eleven 
years at the MIE. This led to the idea of creating a set of 
photogrammetric software for our own use, according to the 
routines and algorithms that were implemented since 1993. 
Unfortunately, there was no point in creating a softcopy kit to 
compete against well-known software, like those that were 
already been used at the Department of Cartographic 
Engineering (ZI SSK and DVP). If something had to be 
developed. it should be a modest project and have a different 
approach to the subject. That is where the whole "educational" 
concept fits in. 
The idea behind the E-FOTO project was to offer a simple set 
of software that could help our students understand the 
principles behind Photogrammetry. Engineers are supposed to 
comprehend how technologies related to their field of 
knowledge work, and if they were presented to a self-teaching 
software, it would be a lot easier to make them understand and 
extract the maximum amount of information from full-featured 
commercial systems. 
This concept sounded right and soonly evolved to the current 
model, which can be explained by the “two-pillar approach” 
(Brito, Coelho, 2002). This means that the E-FOTO project is 
based on two main principles (pillars): freedom and self- 
teaching. 
“Freedom” means that the software is freely distributed, 
according to the principles devised by the Free Software 
Foundation. Its license is the GNU GPL (Gnu's Not Unix 
General Public License) one, which means that the users may 
distribute the software, look at its source code and modify it. It 
is also free of charge. 
"Self-teaching" means that some sort of help is available, so, 
the user will not be left alone with the software. There's a brief, 
but explanatory on line help accompanying the software and an 
e-book on Digital Photogrammetry, which tries to explain its 
principles according to the software approaches. 
The final idea is to lead the students to fully understand the 
princples behind Photogrammetry — reading the e-book, using 
the software, taking a look at its source code and even modifing 
it or developing new modules to it. The way the whole project 
is being implemented will be described on next section. 
2.DEVELOPMENT 
2.1Conceptual Model 
First of all, the applications that would take part of E-FOTO 
should be described. A simple scheme is shown at Figure 1. In 
order to make the software developed as educational as 
possible, only the essential modules were included. Each one 
of them is to be related to a chapter of the e-book that comes 
with them. 
For each module, there should be a useful help file, describing 
the main tasks that must be performed in order to make the 
software work properly. This file might be accessed through 
the main application. 
Also, an e-book covering all subjects related to the theme, and 
paying special attention to the workflow described before must 
be distributed. It will present full explanations to the concepts 
96 
the user needs to know in order to explore the science and 
technology behind Photogrammetry. 
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Figure 1. E-FOTO workflow 
  
  
  
Finally, these pieces of information should be eu and freely 
available to all who want to study them. 
2.2Implementation 
The algorithms are being developed using the C++ 
programming language, and the multiplatform (Linux, Win32. 
Mac) GUI toolkit Qt 2.3.0. Under Linux, Qt is free, and this 
version of E-FOTO is released under the already famous GNU 
GPL (General Public License). For Microsoft (R) Windows, Qt 
has a non-commercial version, which is not GNU compliant. 
Because of this, the usage of this version is not encouraged, but, 
as the source code is freely provided, it can be compiled under 
these two platforms, with no restrictions. 
Qt makes easier the hardwork related to developing a software. 
It already has all sorts of graphic objects, such as buttons, 
forms, panels, radio buttons and check boxes. It also has built- 
in mathematical functions, like operations with matrices, that 
are very useful for any kind of image processing operation. 
Plus, it is multi-platform, which means that the exact same 
sourcecode can be compiled under different OS (Windows, 
Unices and Macintosh), provided that the user has the specific 
license for each platform (GNU for Unices, freeware for 
Windows and paid for Macintosh). Figure 2 shows a simple 
screenshot of one of E-FOTO's modules. 
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