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comparison between a Photogrammetric
plotting made with an analytical instrument
and a plotting performed with techniques of
digital Photogrammetry, in terms of
differences of points coordinates.
2. Objective and execution of the search
The test has been conducted using a couple of
frames in white and black of the territory of
Fasano (BR) during a flight for the realisation
of the cartography to the scale 1:1000.
The characteristics of the flight can be so
reassumed:
• Metric Camera: RMK Zeiss
• Focal distance: 153 mm
• Average of the frame climbs: 1:5000
• Area covered by every frame: 1 Km 2
The software used in the Photogrammetric
Digital process has been Stereo view 300
developed from Menci-scientific software and
kindly envoy to disposition from the Nikon
Ins. S.p.A.
The fundamental characteristics of this
Photogrammetric System can be so reassumed:
• image processing;
• vector processing;
• models orientation;
• 3d digital model representation.
With reference to the models orientation, the
software allows the use of different
algorithms: autocalibration, classic method,
bundle block adjustment, space resection.
The Photogrammetric Digital System
Stereoview allows the stereovision through a
pair of active polarised glasses.
The digital photogrammetric system has been
installed on a PC which characteristic can be
reassumed:
• processor Intel Pentium II, 333 Mhz;
• graphics card Matrox Millennium II, 4 Mb
VRAM;
• video Nokia 445X multysinc, vertical
frequency of refresh of 85 Hz
• resolution of 1280x1024.
The images used in the digital plotting have
been opportunely scannerized.
The transformation of a metric frame in a
digital image is today a very easy operation.
It is well known that the digital sampling can
happen both with a correct control of the
induced deformations, from a
photogrammetric point of view, through
expensive and sophisticated systems and with
easy and economic plain scanners destined to
the market of diffused computer science.
With both the typologies of instruments of
acquisition, the resolution can arrive to high
values (from 1200 to 4000 dpi) but only in the
first ones we have a checked opt-mechanics
construction and of extreme quality.
The answer and the radiometric constancy of
both the instrumental classes is of high quality
and it follows a continuous progress caused by
the increasing question of digital process.
Vice versa the correct sizing of mechanics,
dimensional stability and the geometric
repeatability in the acquisition of the sampling
are characteristic possessed only by the most
expensive systems, projected and built
specifically for a photogrammetric use.
For this experience we have followed the most
economic road, based on the use of a scanner
of good quality but not specifically projected
for Photogrammetric uses.
The original frames have been numerized with
a plain DTP scanner Umax formed A3 of
average quality.
To avoid more losses of definition and to not
introduce ulterior geometric deformations, the
negative ones has been acquired in original
B/W directly; subsequently we have effected
the inversion of grey tones and some
numerical filtratures to have a control of the
general contrast and an increase of apparent
neatness.
In this way, we have obtained two TIFF files
raster in gray scale, with a resolution of 1400
dpi and a dimension of around 170 Mb each.
The dimensions of the ground pixels, equal to
around 11 cm have naturally determined, as in
all the Digital Systems, the resolution in the
measure of the image coordinates.
To be able to go up again to the correct image
of the acquired photo it has necessary become
the calibration of the scanner before
proceeding to the acquisition of the images, in
way to obviate to the drawbacks of inherent
