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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004 
bytes; 
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memorized as an integer (2 or 4 bytes). 
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Fig. 16: A GIS visualization of orthophoto images 
If the height is expressed in cm, 2 bytes can represent a value 
that is between -327.67 m and 4327.68 m. The memory 
required to store a ortho solid image is only 66 96 greater than a 
simple orthophoto. If the considered heights are greater than 
these limits, 4 bytes that are able to represent any possible value 
in floating point format (up to 9999.99 m) can be used. 
This new project permits to extract 3D information from the 
described objects in an easy and cheap way. In fact, an *ad hoc" 
software, that allows simple functions to query an ortho solid 
image, has been developed in Visual Fortran (with GINO 6.0 
graphic libraries): this package provides zoom and pan 
functions, a 3D coordinate viewer and some measurement tools 
that are easy to use even by unskilled operators. The Windows 
Un 
O2 
  
interface of this software is shown in figure 17. 
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Figure 17: An example of an Ortho Solid Image 
8. CONCLUSIONS 
The true digital orthophoto is a product that is particularly 
suitable for the representation of urban areas by large scale 
maps and it is an important instrument for the integration of the 
practical aspects of GIS/LIS in a municipal environment. The 
generation of a DDTM through the use of already existing 3D 
digital cartography leads to a reduction of the production costs 
of the orthophoto, making it necessary to restitute only some 
monumental and new buildings. The ACCORTHO software, 
integrated with the GENEDDTM module, after the 
modifications that have here been described, allows true 
orthophotos to be produced in a quick and cheap way with a 
high degree of automation. The Ortho Solid Image is a new 
user-friendly tool that merges the image information contained 
in true orthophotos with the height information of DDTMs, to 
give a complete 3D description of the represented object. 
References 
F. Amhar, R. Ecker, 1996. An integrated solution for the 
problems of 3D man-made objects in digital orthophotos. 
International Archives of Photogrammetry and Remote Sensing, 
Vol. XXXI, Part B4 
K. Kraus, 1997. Photogrammetry. Reading: Dümmlers Verlag. 
Vol. 2 
Spalla A., 2002. La cartografia 3D della TIM prodotta con 
fotogrammetria diretta. Atti del Convegno internazionale “La 
fotogrammetria nell'era inerziale", Pavia, 13-14 giugno 
M. A. Brovelli, M. Reguzzoni, F. Sansó, G. Venuti, 2001, 
Modelli matematici del terreno per mezzo di interpolatori a 
spline, Bollettino SIFET, supplemento al n. 2/2001 
Dequal S., Lingua A., 2001. True orthophoto for Architectural 
Surveys. Proc. *XVIII" International Symposium of CIPA — 
Postdam (Germany)". pp. 269-276 
Bornaz L., Dequal S. 2003. The solid image: a new concept and 
its applications. Proc. “XVIII” International Symposium of 
CIPA — Postdam (Germany)”