Areas of
calibration
35% 4% 4% 51% 58% 64% 92%
68% 89% 96% 98% à 99%
15% 9% 98%
Table 4: Percentiles of the differences between the remaining
calibration areas of image 5419 which are lower than the
thresholds indicated by the column headers
The calibration area 2 shows a very low consistency with the
others (lower than 50% at the 20 cm threshold), thus it was
discarded.
Calibration areas 3, 6 and 7, on the other hand, are consistent
both with each other and with the NRTK survey. The DSBMs
obtained from them can thus be considered valid and equivalent.
4.2 Image 5318
The different calibration areas for the image 5318 were
processed in the same way.
Area of Average Standard
calibration (m) deviation (m)
1 000 0.38
3 0.27 0.34
4 027 : 0.34
| 7|| 0.50] | 0.29]
8 0.13 t 0.47
Table 5: Averages and standard deviations of the differences
between the points of the DSBM and those of the NRTK survey
for the calibration areas of the 5318 image
The calibration areas 6 and 10 produced DOPs that did not
overlap with the NRTK survey, thus they were discarded. Area
7 was also discarded due to excessive average differences with
the NRTK.
The comparison between the remaining DSBMs proceeded with
the same methods as for image 5419. The results are shown in
the following
Table 6.
All the calibration areas shown internal consistency at the 20 cm
threshold. The DSBMs produced from all of them are thus
considered valid and equivalent. Finally, with the same method
the valid DSBMs obtained from the 5419 image were compared
with the ones from the 5318 one.
The table 7 shows no percentiles over 50% for thresholds under
0.6 m. Thus, this appears to be the limit for the precision of the
method.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
Areas of
calibration
22% 56% 79% 91% 94% 96% 98% 99%
38% 71% 88% 94% 97% 99% 99% 100% 100%
44% 179% 90% 98% 98% 99% 100%
Table 6: Percentiles of the differences between the remaining
calibration areas of image 5318 that are lower than the
thresholds indicated by the column headers
5. CONCLUSION
Based on the comparisons made here we can say that, despite
the two images being different in geometry and quality, the
results coincide to a precision of about 0.6 m. This first
approximation will allow us to choose the quality parameters of
the bathymetric surveys which will be used to calibrate the
method. For the immediate future, in fact, we are planning a
bathymetric survey of a wider area, which will allow us to
create the DOP zones for the other bands of the sensor, and
especially for the Coastal band.
calibration
9% 24% 37% 4% 53% 6% 6% 71% 71% 859
21% 37% 4% 5% 60% 6% 7% 81% 89% 95%
2% 4% 14% 30% 4% 50% 58% 65% 729^ 83%
Table 7: Percentiles of the differences between the remaining
calibration areas of image 5419 and those of image 5318 which
are lower than the thresholds indicated by the column headers.
This research was co-financed by the Autonomous Regional
Government of Sardinia (Regione Autonoma della Sardegna)
with funds from the “PO Sardegna FSE 2007-2013” and the
Regional Law 7/2007 “Promotion of scientific research and
technological innovation in Sardinia"
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