ciPA 2003 XIX 11 ' International Symposium, 30 September-04 October, 2003, Antalya, Turkey
These functions are offered, for example, by the ENVI
software (Environment for Visualizing Images, by Research
Systems Inc). (Fig. 9).
Figure 9. Overlap between the original colour image and the
grey distance matrix
Once the solid image has been built, the main important
result is achieved: for each pixel, it is easy to compute in real
time the XYZ position of the object point in an absolute
reference system and to display the 3 coordinates on the
screen (see Fig. 10).
Figure 10. The solid image and the cursor giving the XYZ
object co-ordinates of the pointed pixel
5. SOME APPLICATIONS
5.1 A coloured 3D model
One of the possible opportunities offered by the solid image
is the creation of a 3D model of the represented object. The
R, G and B radiometric values and the 3D coordinates are in
fact known for each pixel of the image. When this
information is known, it is possible, in a very simple way, to
create a three-dimensional model to which a radiometric
value corresponds to every object point in the space. The
mathematical model used for this operation is the central
perspective model.
One of the 3D models that is possible to create with the Solid
image Maker software is a VRML (Virtual Reality Modelling
Language) model. This 3D model can be visualized with
specific software for browser web (for example the COSMO
player or the CORTONA VRML player for Explorer or
Netscape).
a)
b)
Figure 11. a) The 3D model - b) The 3D RGB coloured
model - VRML model shown with CORTONA VRML
player for browser web.
All these display devices are found free of charge in Internet.
This type of software has a great drawback: the model can
only be visualized, but not measured.
In the case where the metric aspect of the represented object
is considered to be much more important than its simple
visualization, using the solid image maker it is possible to
export the 3D model in some other graphic formats (for
example DXF and ASCII text file formats). In this case it is
not possible to associate a radiometric values to each point in
the space. The model will therefore not be coloured.
5.2 An artificial stereo pair
Another product obtainable from the solid image is an
artificial stereo pair. This couple of images is obtained by
fixing a taking base that can be chosen by the operator. The
mathematical model used for this operation is the central
perspective projection.
