International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004
software reads the orientation and calibration parameters of
the image and the values contained in the R, G, B, D and A
matrices of each pixel of the image on which the cursor is
positioned and, using these values, it calculates the X, Y and
Z coordinates of the point. These values are made visible to
the operator, in real time, in a specific visualisation window
(see figure 4).
2.2. Calculation of a mean plane
LSR 2004 allows a set of measurements to be directly carried
out on the Solid Image. One of these measurements is the
computation of the mean plane of a set of points. This kind
of measurement could be useful, for example, for geologists,
who often have to determine the position of planes on the
external face of a rock mass, in order to understand the
internal fracture situation. It is in fact possible to
automatically determine the barycentre of the points and the
dip and dip direction values of the plane. The mean plane can
be calculated, using LSR 2004, in two different ways: by
choosing a set of points on the image or by defining an area
containing the points from which the mean plane can be
calculated (see figure 5).
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Figure 5. Determination of the mean plane defined by a set of
points
After the definition of the points that have to be used in the
calculation, the mean plane is calculated through a least
square method. The estimated parameters (mean square error
of the estimation, mean and maximum distances between the
points and the plane, etc.) are shown in a specific window.
2.3 Plug-in for Photoshop®
LSR 2004 is a software that allows one to create, visualise
and manage a solid image. At present a plug-in is being
developed for the well known Adobe Photoshop® software
that allows the Solid Image to be visualised.
This gives the opportunity of using the power of Photoshop
in enhance the quality of the original image (filtering,
contrast, balancing, ...).
It is obvious that the size of the original image should not be
changed, otherwise the D and A matrices will not fit with the
new interpolated image.
The use of this software will also allow inexperienced users
to take advantage of the potentialities that are offered by the
Solid Image, to correctly explore a complex 3D model and to
carry out 3D measurements.
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Figure 6. Photoshop plug-in for the visualisation of the
Solid Image — Solid Image of the Tetrarchi statue in Venice
3. EXAMPLE OF A SOLID IMAGE
3.1 Example of a Solid Image
The complete procedure for the creation of a Solid Image has
been performed on different objects acquired with laser
scanner devices. One of these objects is the front entrance of
the San Marco Basilica in Venice.
Figure 7. The front entrance of the San Marco Basilica in
Venice
3.2 The survey
A complete survey of the front entrance has been performed
in order to obtain its Solid Image (topographic +
photogrammetric + laser scanner). A Riegl LMS-Z420 laser
scanner with an accuracy of + 5 mm was used for the DDSM
acquisition. The minimum angular step is 10 mgon.
The laser scanner acquisition was carried out from a mean
distance of 20 m and with angular steps of 20 mgon, in about
1 hour 30 minutes.
In addition to the laser survey, a photographic survey of the
statue was performed using a semimetric Rollei 6008 camera
with a 28 mm lens.
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