Page 104 - Studia Universitatis Hereditati, vol. 5(2) (2017)
P. 104
dia universitatis her editati, letnik 5 (2017), številk a 2 104detail and precision of the 3D scans is directly re-ners are typically used in industrial applications
lated to the density ratio of the laser beams6. such as plants and refineries, or interior architec-
hereditatiLaser scanning technologies tural spaces.
Phase-Shift (PS)
Time-of-Flight (TOF)
Figure 4. Schematic illustration of the phaseshift The time-of-flight method works by sending a la-
Phase-Shift technology work by sending out a ser pulse of light and then measuring the time it
continuous laser beam with a modulated signal takes to travel from the scanner to the object and
embedded in the laser. The scanner compares the back, with collected data scanner calculate the
phase of the signal at the source with the phase distance.9 The detector od the scanner will gen-
of the laser light once it has travelled to the ob- erate a time-tagged trigger pulse depending on
ject and reflected back to the scanner. Recorded set up criteria. Some of the detection methods
changes of phase in laser light are measured and take characteristic points of the pulse path as the
allows the scanner to calculate the distances.7 In decisive factor10. Based on the speed of light, we
comparison to Time-of-flight scanners, PS scan- knew the time that laser need to reach the desti-
ners have a lower operational range (80 meters, nation and get back to the sensor, thanks to that
with some systems reaching up to 120 meters), the location of the object can be determined.
but can capture more points per second with a A fundamental property of the light wave is its
higher precision. Generally, PS scanner operates propagation velocity. In a given medium, light
similarly to TOF scanner. The main difference is waves travel with a constant but finite velocity.
that PS scanner calculates the time of flight by The measurement itself is represented by time
measuring the difference in the phase of the laser delays (referred to as the ‘time-of-flight’) created
as it returns to the scanner.8 Phase-based scan- by light travelling in a medium from the source
to the reflective target surface, and back to the
6 Benli, Gulhan, and Ozer Derya Gulec. “USE OF LASER SCAN- source.11 The advantage of this technology is the
NING FOR CULTURAL HERITAGE DOCUMENTA- significant increase the data capturing speed, up
TION”. International Journal of Electronics, Mechanical and to several million points per second. TOF is typ-
Mechatronics Engineering (IJEMME) 3/1 (June 2013): 447 ically used for exterior civil/survey applications
such as topographic surveys of roadways and
7 Julia, Armesto-González, Belén Riveiro-Rodríguez, Diego buildings, since the key benefit of this type of la-
González-Aguilera, and M. Teresa Rivas-Brea. “Terrestrial laser ser scanning technology is its capability of cap-
scanning intensity data applied to damage detection for histor- turing data from a greater distance (from sever-
ical.” Journal of Archaeological Science 37, no. 12 (December, 2010): al hundred up to several thousand meters), while
3037-3047, doi: 10.1016/j.jas.2010.06.031.; Alonso J.I., San José, Jose maintaining the accuracy in the order of centi-
Martínez Rubio, José Fernández Martín Juan, and Jorge García metres or smaller units. 12
Fernández. “Comparing Time-Of and Phase-Shift the Survey of
the Royal Pantheon in the Basilica of San Isidoro (LEÓN)” Interna- Journal of Archaeological Science 37, no. 12 (December, 2010): 3037-
tional Archives of the Photogrammetry, Remote Sensing and Spatial Infor- 3047, doi:10.1016/j.jas.2010.06.031.
mation Sciences, Volume XXXVIII-5/W16, (September, 2011): 377-385, 9 Julia, Armesto-González, Belén Riveiro-Rodríguez, Diego
doi: 10.5194 / isprsarchives-KSKSKSVIII-5-V16-377-2011. González-Aguilera, and M. Teresa Rivas-Brea. “Terrestrial laser
scanning intensity data applied to damage detection for historical.”
8 Julia, Armesto-González, Belén Riveiro-Rodríguez, Diego Journal of Archaeological Science 37, no. 12 (December, 2010): 3037-
González-Aguilera, and M. Teresa Rivas-Brea. “Terrestrial laser 3047, doi: 10.1016/j.jas.2010.06.031.
scanning intensity data applied to damage detection for historical.” 10 George, Vosselman and Hans-Gerd Maas. Airborne and Terrestrial
Laser Scanning. (Dunbeath: Whittles Publishing, 2010), 5
11 George, Vosselman and Hans-Gerd Maas. Airborne and Terrestrial
Laser Scanning. (Dunbeath: Whittles Publishing, 2010), 3
12 Massimiliano, Pieraccini, Gabriele Guidi and Carlo Atzeni. “3D
digitizing of cultural heritage.” Journal of Cultural Heritage 2 (1), (
March, 2001): 63-70, doi: 10.1016 / S1296-2074 (01) 01108-6.; Naci,
lated to the density ratio of the laser beams6. such as plants and refineries, or interior architec-
hereditatiLaser scanning technologies tural spaces.
Phase-Shift (PS)
Time-of-Flight (TOF)
Figure 4. Schematic illustration of the phaseshift The time-of-flight method works by sending a la-
Phase-Shift technology work by sending out a ser pulse of light and then measuring the time it
continuous laser beam with a modulated signal takes to travel from the scanner to the object and
embedded in the laser. The scanner compares the back, with collected data scanner calculate the
phase of the signal at the source with the phase distance.9 The detector od the scanner will gen-
of the laser light once it has travelled to the ob- erate a time-tagged trigger pulse depending on
ject and reflected back to the scanner. Recorded set up criteria. Some of the detection methods
changes of phase in laser light are measured and take characteristic points of the pulse path as the
allows the scanner to calculate the distances.7 In decisive factor10. Based on the speed of light, we
comparison to Time-of-flight scanners, PS scan- knew the time that laser need to reach the desti-
ners have a lower operational range (80 meters, nation and get back to the sensor, thanks to that
with some systems reaching up to 120 meters), the location of the object can be determined.
but can capture more points per second with a A fundamental property of the light wave is its
higher precision. Generally, PS scanner operates propagation velocity. In a given medium, light
similarly to TOF scanner. The main difference is waves travel with a constant but finite velocity.
that PS scanner calculates the time of flight by The measurement itself is represented by time
measuring the difference in the phase of the laser delays (referred to as the ‘time-of-flight’) created
as it returns to the scanner.8 Phase-based scan- by light travelling in a medium from the source
to the reflective target surface, and back to the
6 Benli, Gulhan, and Ozer Derya Gulec. “USE OF LASER SCAN- source.11 The advantage of this technology is the
NING FOR CULTURAL HERITAGE DOCUMENTA- significant increase the data capturing speed, up
TION”. International Journal of Electronics, Mechanical and to several million points per second. TOF is typ-
Mechatronics Engineering (IJEMME) 3/1 (June 2013): 447 ically used for exterior civil/survey applications
such as topographic surveys of roadways and
7 Julia, Armesto-González, Belén Riveiro-Rodríguez, Diego buildings, since the key benefit of this type of la-
González-Aguilera, and M. Teresa Rivas-Brea. “Terrestrial laser ser scanning technology is its capability of cap-
scanning intensity data applied to damage detection for histor- turing data from a greater distance (from sever-
ical.” Journal of Archaeological Science 37, no. 12 (December, 2010): al hundred up to several thousand meters), while
3037-3047, doi: 10.1016/j.jas.2010.06.031.; Alonso J.I., San José, Jose maintaining the accuracy in the order of centi-
Martínez Rubio, José Fernández Martín Juan, and Jorge García metres or smaller units. 12
Fernández. “Comparing Time-Of and Phase-Shift the Survey of
the Royal Pantheon in the Basilica of San Isidoro (LEÓN)” Interna- Journal of Archaeological Science 37, no. 12 (December, 2010): 3037-
tional Archives of the Photogrammetry, Remote Sensing and Spatial Infor- 3047, doi:10.1016/j.jas.2010.06.031.
mation Sciences, Volume XXXVIII-5/W16, (September, 2011): 377-385, 9 Julia, Armesto-González, Belén Riveiro-Rodríguez, Diego
doi: 10.5194 / isprsarchives-KSKSKSVIII-5-V16-377-2011. González-Aguilera, and M. Teresa Rivas-Brea. “Terrestrial laser
scanning intensity data applied to damage detection for historical.”
8 Julia, Armesto-González, Belén Riveiro-Rodríguez, Diego Journal of Archaeological Science 37, no. 12 (December, 2010): 3037-
González-Aguilera, and M. Teresa Rivas-Brea. “Terrestrial laser 3047, doi: 10.1016/j.jas.2010.06.031.
scanning intensity data applied to damage detection for historical.” 10 George, Vosselman and Hans-Gerd Maas. Airborne and Terrestrial
Laser Scanning. (Dunbeath: Whittles Publishing, 2010), 5
11 George, Vosselman and Hans-Gerd Maas. Airborne and Terrestrial
Laser Scanning. (Dunbeath: Whittles Publishing, 2010), 3
12 Massimiliano, Pieraccini, Gabriele Guidi and Carlo Atzeni. “3D
digitizing of cultural heritage.” Journal of Cultural Heritage 2 (1), (
March, 2001): 63-70, doi: 10.1016 / S1296-2074 (01) 01108-6.; Naci,
