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Verifying the possibilities of using a 3D laser scanner in the mining underground

Authors:

Abstract

Presented contribution introduces our current utilization knowledge of the pulse scanner Leica ScanStation C10 in situ mine workings. It is a device with a long-range laser beam that has excellent positional, length and angular accuracy and a very high speed laser scanning with a possibility of photographic documentation of scanned scene. The possibility of its use in mining conditions was tested in mine workings in closed polymetallic deposit of Zlaté Hory (Olomouc region, Czech Republic). Within realized surveying campaigns, the possibilities of using this technology were verified, especially for documentation of the current technical condition of the mines and their real spatial definition. Furthermore, it is possible to monitor and determine the spatial changes in mine features (movements and deformations). The analysis of the data based on the undertaken scanning campaigns and also with regard to the physical and technical constraints that were encountered, the technological procedures of each type of scanning were subsequently adjusted to the specific conditions. © 2015, Academy of Sciences of the Czech Republic. All rights reserved.
Acta Geodyn. Geomater., Vol. 12, No. 1 (177), 51–58, 2015
DOI: 10.13168/AGG.2015.0004
journal homepage: http://www.irsm.cas.cz/acta
ORIGINAL PAPER
VERIFYING THE POSSIBILITIES OF USING A 3D LASER SCANNER
IN THE MINING UNDERGROUND
Vlastimil KAJZAR *, Radovan KUKUTSCH and Nikola HEROLDOVÁ
Institute of Geonics, Academy of Sciences of the Czech Republic, v.v.i., Studentská str. 1768,
708 00 Ostrava-Poruba, Czech Republic
*Corresponding author‘s e-mail: vlastimil.kajzar@ugn.cas.cz
ABSTRACT
Presented contribution introduces our current utilization knowledge of the pulse scanner Leica
ScanStation C10 in situ mine workings. It is a device with a long-range laser beam that has
excellent positional, length and angular accuracy and a very high speed laser scanning with
a possibility of photographic documentation of scanned scene.
The possibility of its use in mining conditions was tested in mine workings in closed
p
olymetallic deposit of Zlaté Hory (Olomouc region, Czech Republic). Within realized
surveying campaigns, the possibilities of using this technology were verified, especially
for documentation of the current technical condition of the mines and their real spatial definition.
Furthermore, it is possible to monitor and determine the spatial changes in mine features
(movements and deformations).
The analysis of the data based on the undertaken scanning campaigns and also with regard to the
p
hysical and technical constraints that were encountered, the technological procedures of each
type of scanning were subsequently adjusted to the specific conditions.
ARTICLE INFO
A
rticle history:
Received 4 September 2014
Accepted 29 January 2015
Available online 11 February 2015
K
eywords:
3D laser scanning
Underground
Mining
Leica ScanStation C10
This technology also starts to take over in
quarries for the purpose of topographic mapping or
monitoring of advance of the quarry material and
determination of the volume of such material etc.
(project references of Arcadis, Geotronics o
r
Severočeské doly company).
From a global point of view, the published
papers by e.g. Huber and Vandapel (2003),
Somervuori and Lamberg (2009), Jonsson et al.
(2009), Fekete et al. (2010), Xiling et al. (2011) o
r
Feng (2012) are worth mentioning.
The wider utilization of this technology is in
cave rooms, not only in the Czech Republic, but also
abroad (Buchroithner, 2009; Cosso et al., 2014).
Unfortunately, the use of this technology is still
limited in mining environment, with some exceptions
(e.g. DMT GmbH or Measurement Devices Ltd. UK).
But this technology has never been used in the Czech
Republic so far.
A small frequency of its use is determined not
only by the price of the device, but also primarily by
the specifics of such environment. At the Institute o
f
Geonics, there was a possibility to use this method in
situ followed by several tests in the specific mining
conditions in order to develop scanning methods in
different types of mines. It should solve mostly fo
r
p
urpose of documentation of current technical
condition of mines, for their actual spatial surveying
and also for the possibility of monitoring the spatial
changes of mining objects (e.g. movements and
deformations). This task is important for scanning
b
oth, existing and historic mine workings. In the
p
aper, the attention is also paid to possible restrictions
INTRODUCTION
Laser scanning systems excel in ability to
contactless determine spatial coordinates of any
spatial objects, such as buildings, structures, interiors,
space, terrain, etc. and with exceptional speed,
accuracy, complexity and safety. The scanned objec
t
is then visualized by specialized software as the cloud
of points. Subsequently, it is possible to perform
a wide range of analytical tasks and also to generate
models of the object.
The basic principle of the device works in the
similar way to radar. The device emits a
p
ulse and
captures its reflection. It is possible to calculate the
distance to the point of reflection based on the time
b
etween sending the pulse and receiving back its
reflection. Due to pulse transmission of the narrow
laser beam in different directions in a relatively short
p
eriod of time (thousands to hundreds of thousands
emitted pulses per second), it is possible to targe
t
individual spatial scene with high precision and
resolution. The spatial position of each point is
thereafter calculated by spatial polar method.
In the context of well-known practice, using 3D
laser scanner in mining environment was so far very
limited in the Czech Republic. The principles of 3D
laser scanning are used in the Czech Republic fo
r
more than 10 years. This technology is used mainly in
geotechnology in terms of surveying the real
condition of tunnels and adits, assessment of lining
shape and other building components, volume o
f
overbreaks (e.g. tunnels Klimkovice, Dobrovského,
Panenská, Lochkov and Prague underground
constructions). (Středa, 2011; Vaníček, 2012).
V. Kajzar et al.
52
The device uses the green laser beam with
wavelength of 532 nm. Based on the intensity o
f
reflected beam, the device can distinguish different
types of planes within the point cloud. There is
a possibility of scanning in the full field of view (see
Fig. 1). ScanStation C10 is able to measure on
distance up to 300 m in ideal reflectivity conditions.
The shortest distance of detection is 0.1 m. The device
is also complemented by integrated digital camera.
In terms of spatial resolution scanning, the close
r
the scanned object is the closer the points defining the
object are to each other (see Fig. 2). The device is able
of using the laser scanner technology based on such
difficult conditions.
Based on the realized campaigns, subsequen
t
analysis and knowledge’s of physical and technical
limitations, the technological scanning procedures fo
r
each type of scanned objects were specified.
ORE MINES JESENÍK, ZLATÉ HORY LOCALITY
Zlaté Hory locality is located about 7 km from
the Zlaté Hory town. This locality is a historical
mining district, where the ore mining dates back to the
14th century. Since that time, there has been several
times a boom and recession of mining. The last stage
of mining here has been implemented in the postwar
years until the 90s of the 20th century. Thanks to the
p
olitical and social changes, the ore mining industry
underwent a restructuralization. Therefore, all ore
mines, except uranium mines, have been shut down in
the Czech Republic.
In the latest stage of mining in Zlaté Hory,
7 184.4 kt monometallic and polymetallic ores incl.
gold was mined in total. Opening of ore deposit was
provided by 4 pits, 14 adits, 4 slope adits and
11 chutes. The total length of the mine workings
exceeds 140 km (Vranka and Kukutsch, 2011).
The Zlaté Hory locality has not been chosen for
the purpose of 3D laser testing randomly. After the
year 1990, this locality has been considered as one o
f
the potencial places where to build an underground
mining research base and it was planned primarily for
the service and research purposes. Unfortunately, the
lack of consensus led to complete failure of all plans
and this idea ended only in stage of detailed study.
Although, after more than 15 years, the working place
like this was needed again. Therefore, the Josef adi
t
near Mokrsko is being used for these purposes in
p
resent days. The big advantage of testing in Zlaté
Hory location is zero operational activity, because
none of mine workings belong to the category o
f
mines in operation. Thus, it was possible to verify the
p
otential of laser scanning in mining environment
with its specific features, which can be expected in
such difficult conditions. In the environment of Zlaté
Hory-East and Zlaté Hory-South, the mines were
scanned with both, spatial and surface variability. The
linear and also large mine workings, mine workings
with and without dipping, reinforced and non-
reinforced, dry, half flooded or flooded parts were
scanned.
LASER SCANNING IN MINING UNDERGROUND
Since 2011, the Institute of Geonics disposes and
actively utilizes a static terrestrial laser scanning
system. Particularly, it deals with the Leica
ScanStation C10 of Leica Geosystems AG. It is
a compact pulse scanner with dual-axis compensator,
featuring high speed scanning (up to 50 000 points pe
r
second), high surveying precision and long-range
beam.
Fig. 1 Full field of view of the scanner Leica
ScanStation C10.
to distinguish different points in mutual distance o
f
1 mm.
The indicated 3D accuracy of measured points is
6 mm which means that the real distance between the
device and the object is 4 mm. The angular accuracy
is 60 μrad (see Fig. 3). More accurate determination o
f
accuracy is the matter of repetitive and comparative
measurements and statistical evaluations. However,
the range in millimeters is more than adequate for the
wide-variety of utilization requesting the accuracy in
centimeters.
L
IMITING FACTORS OF UNDERGROUND
S
CANNIN
G
The primary application of laser scanning is to
capture the current condition of mines. The quality o
f
the resulting scanned point clouds depends on many
factors. It showed up, that not only the limiting
factors, but also the very limitations of the device
equipment are based on the specific characteristics o
f
the mining environment. There are several limitations
while scanning underground:
inadequate lighting conditions, respectively
darkness (problematic stabilization of surveying
apparatus, problems with visibility of targets, the
limitations of the integrated camera, etc.),
dust (reduced visibility in mine workings, the
need of filtration of the air flowing into the
scanner, etc.),
Source: Leica Geosystems AG
VERIFYING THE POSSIBILITIES OF USING A 3D LASER SCANNER…
.
53
10 m
3D S canner
25 m 50 m 100 m 150
m
1 cm
2.5 cm
5 cm
15 cm
10 cm
Fig. 2 Planar view on two consecutive scan lines in spatial resolution of 10x10 cm, at 100 m distance an
d
adequate theoretical resolution for other distances (Kuda et al., 2014).
10 m
3D Scanner 25 m 50 m 100 m
12''
4 mm
1.5 mm
x
Z@
y
0.6@
mm
0.6
1.5@
mm
1.5
2.9@
mm
2.9
5.8@
mm
5.8
Fig. 3 Schematic overview of the basic measurement errors for ScanStation C10 (Kuda et al., 2014).
Highest Resolution
0.02 m/100 m
Scanned window: 30 min
Full field of view: 170 min
High Resolution
0.05 m/100 m
Scanned window: 9 min
Full field of view: 28 min
Custom Resolution
0.07 m/100 m
Scanned window: 4:30 min
Full field of view: 14 min
Medium Resolution
0.10 m/100 m
Scanned window: 2:15 min
Full field of view: 7 min
Low Resolution
0.20 m/100 m
Scanned window: 1 min
Full field of view: 1:45 min
Custom Resolution
0.50 m/100 m
Scanned window: 0:15 min
Full field of view: 0:45 min
Fig. 4 Dependence of the duration and density of scanning on the type of spatial resolution.
V. Kajzar et al.
54
Fig. 5 Albedo on example of copper discharges, so-called "Blue Lady".
S
CANNING RESOLUTION OPTIMIZATION
The main factor of the quality of outputs that can
b
e influenced is the scanning resolution setting. The
goal of one of the initial scanning campaign was
therefore to verify the scanner possibilities in the
terms of testing the scanner resolution. For better
orientation in this field Figure 4 was created. It
p
resents the dependence of scanning time on the type
of selected spatial resolution. Given times describe the
execution time of scanning of the rock mass defined
by scanning window (in this case the size is about
3.2 x 1.8 m), respectively the full field of view (see
Fig. 1). The point density of final point cloud is
clearly demonstrated in 0.2 x 0.2 m detail below.
THE DIFFERENT LEVELS OF REFLECTIVITY
Another key factor of the quality of outputs,
which can be not influenced, is called albedo,
expressing the reflectivity level of the object, resp. its
surface. It is the ratio of the reflected electromagnetic
radiation to the amount of incident radiation. This
attribute of various types of the materials can
significantly affect obtained output. It also shows that
another problematic factor was scanning of the dark,
highly reflective or transparent materials (Štroner e
t
al., 2013).
A very good example of different levels o
f
reflectivity is shown in Figure 5. A phenomenon so-
called "Blue Lady", represented by the brighter patch,
is captured in this image. In fact, it is a flat coating o
f
a blue color caused by overflowing allophane.
A well-known material, which negatively affects
the scanning outputs, is glass, but it rarely appears in
a mining environment. Another substance with the
similar properties is water, respectively the water
surface. The result in the scan is either completely
empty space, because the beam has no chance to
bounce or, in some cases, also scanned reflection o
f
surrounding objects.
humidity (condensation, corrosion limiting the
p
lacement of magnetic targets on the steel
reinforcement of mines, etc.),
water (on the floor, dripping, flowing),
temperature of the rock mass and the surrounding
environment (on the limits of device operating
temperature),
noise (difficulties in communication between
team members),
weight and dimensional parameters of devices
and accessories, requirement to careful handling,
complicated portability,
limited maneuver space,
difficult access to mines (the slopes, obstacles in
the mine, etc.),
disturbance stability of mine workings,
continuous operating activity in mines,
requirements for intrinsic safety (in areas with
potentially explosive mine air),
the need for continuous monitoring of the mine
conditions
and many others.
The important advantages, in terms of device
utilization, are the declared dust and humidity
resistance (IP54) and operating temperature range
from 0°C to 40°C and also the associated battery life
to it. The limiting scanning conditions are those cases,
when it is impossible to obtain the relevant data due to
difficult accessibility of scanned area, for instance
scanning in either narrow or vertical mine workings
usually accessible only from above or from the
b
ottom. Another limiting condition that we were
confronted with was the high humidity and
subsequent condensation of water vapour on the
device.
VERIFYING THE POSSIBILITIES OF USING A 3D LASER SCANNER…
.
55
Fig. 6 Zlaté Hory-East site, 3rd floor, part of crosscut in Zlaté Hory-South site direction.
scanned point, resp. material. Combining the photo
and scanning results, the fair idea of existing
conditions of captured underground mining area can
be obtained.
S
CANNING OF LINEAR
M
INE WORKINGS
The possibility of using the laser scanning to
capture the course of linear mining workings, i.e.
mine corridors were tested on Zlaté Hory-East site,
3rd floor, in direction to the crosscut of Zlaté Hory-
South site.
The mine trolley, on which the measuring
equipment was stabilized, was used for scanning. This
trolley was continuously moved along the rails (see
Fig. 7) to a total of 10 scanning positions situated at
a mutual distance of about 30 m. Resulting scanned
length of the corridor was approximately 250 m.
Finally, the Medium Resolution was used and final
point cloud was formed by 145 million points.
S
CANNING STEP OPTIM
I
ZATION
With the selected step of about 30 meters, the
scanned section was uneven and insufficient. In the
next stage, it was therefore necessary to analyze the
optimal scanning step in order to sufficiently capture
the resulting point cloud of the entire corridor.
Therefore, about 75 m long corridor representing
a classic example of mining gallery in this district was
chosen for this purpose. Within the selected section
we encountered grew rock and reinforced with steel,
concrete and wooden casings, driven grids, rails, dry
and wet floor and other materials. Light profile of the
gallery was of approx. 3.7 x 2.7 m in dimensions.
There were 16 scanning positions located in this
section at a distance of 5 m in total. From each
separate position individual scan was performed. This
was followed by analysis of the selection of optimal
scanning step (see Fig. 7).
Obtained results of performed analysis
completely confirmed that the scan step selection in
the case of linear mine workings play important role.
Scanning with steps of 5 and 10 m can be evaluated as
optimal in these specific conditions, but it also
demands the significant time on the implementation.
Steps of 15 to 25 m can be evaluated as satisfactory.
In this case, step above 25 m can be considered, as
D
ARKNESS AND USE OF THE INTEGRATED
CAMERA
Although the most commonly available
commercial 3D laser scanners dispose of an integrated
camera, the possibility of its use is directly
proportional to the parameters of the resolution and
sensitivity of the sensor. The camera is primarily
designed to make the photographic documentation o
f
the scanned area from the scanning position. The
captured panorama image can be later used to change
the color of point cloud to the real colors.
The general requirement for using the integrated
camera in the underground environment is sufficien
t
illumination of the surrounding area. Due to the lac
k
of flash or any other type of illumination, it is not
possible to use the integrated camera underground. As
a suitable alternative to compensate this deficiency
was using a trio of rechargeable LED lights with
wattage of 20W (the power is equal to conventional
100W reflectors).
Since we don’t need to move in total darkness,
the use of these lights mounted on legs of scanner
tripod (120° shine angle) significantly increases the
comfort of work. However, their use is still provided
b
y the difficulties arising from the distance and
intensity of the light source. There is a direct
correlation valid, the larger the space, the greate
r
p
ower light source is needed, respectively the better
sensitivity of the integrated camera sensor. Despite o
f
the creation of very good light conditions in the tested
area of mining corridors, the quality of resulting
images did not meet our expectations. This was
mainly due to insufficient quality of 4 Mpix sensor
placed in the integrated camera.
PRACTICAL APPLICATION
THE COMBINATION OF LASER SCANNING AND
P
HOTO DOCUMENTATIO
N
Despite of all efforts, the possibility of using the
integrated camera underground did not work. Another
alternative was taking independent pictures of the
entire area by high-quality camera. Figure 6 illustrates
the combination of photography of the selected place
acquired
b
y DSLR camera and the corresponding
selection of acquired point cloud. The intensity of the
gray scale reflects the degree of reflectivity of each
V. Kajzar et al.
56
10 meters scanning step 5 meters scanning step
20 meters scanning step 15 meters scanning step
30 meters scanning step 25 meters scanning step
40 meters scanning step 35 meters scanning step
Fig. 7 Effect of scanning positions distance on the description quality of the mine corridor.
The entire chamber was scanned from 6 differen
t
positions in Medium Resolution (Fig. 4). The essential
p
roblem was the appropriate stabilization of targets in
such enormous space. These targets are used fo
r
consecutive registration of point clouds into the
compact one. The inability to use conventional scan
targets is due to very poor visibility between laser and
target and also due to very difficult movement on heap
of material when the tilt in many parts approaches 40
degrees. This led to the proposal of so called triple-
target (see Fig. 8). It is designed based on appropriate
combination of different parts of the available
measuring equipment. Its advantage is in ability to
rotate individual targets to the corresponding
direction, where the target can be visible from any
p
osition in space. Its disadvantage is the short distance
b
etween single targets. This can cause the significan
t
errors in the registration of point clouds. It means, that
with increasing distance the error determining the
spatial position of the scanned points increases. For
this reason, using this alternative option is
recommended only in occasional cases.
The resulting point cloud is represented by
90 million points. The entire scanned chamber is
introduced by a pair of side views in Figure 9.
CONVERGENCE PROFILES
One of the goals of verification work was also to
verify the possibility of using 3D scanner as a tool for
measuring the convergence profiles (see Fig. 10).
The measurement results from the laser scanning
technology convergence are comparable with the
measurement results obtained by classical methods
unsatisfactory with a high degree of detail loss, and
therefore, its use is not recommended in similar
conditions. There is usually direct dependence
b
etween increasing profile of mine corridor and the
longer step of scanning positions and vice versa.
The new knowledge of the optimal scanning
steps was applied during subsequent scanning of helix
gallery, representing the mine working minted
downhill. The uniqueness of this space was the
original installation of ventilation air pipes and othe
r
obstacles. The occurrence of such significant objects
produces scanning shadows, which means, that areas
are not sufficiently scanned. All those objects make
the scanning very complicated. This is a very common
p
henomenon, which can be eliminated only by
scanning from larger amount of scanning positions.
S
CANNING OF LARGE-SCALE MINE WORKINGS
In the other campaigns, verification of scanning
p
ossibilities of large underground spaces was carried
out. The large-scale mine workings include the works
that are not of linear character and dimensions in
proportion height x width x depth (length) are
relatively similar. In mining and geotechnical practice,
the chambers that were used in both ore mining and
the extraction of brown coal within the various mining
methods are classified as large-scale works.
For this purpose, the selected chamber situated
on the second sublevel of the Zlaté Hory-East site was
scanned. It is an area of irregular shape, with
a maximum ceiling height of 30 meters and the width
about 42 m. Within Zlaté Hory deposit, it is a smaller
chamber.
VERIFYING THE POSSIBILITIES OF USING A 3D LASER SCANNER…
.
57
Fig. 8 Construction of triple-target and definition its targets centers in the point cloud.
Point Cloud (Front View) Point cloud (Right View)
Fig. 9 Scanning locality of Zlaté Hory-East site, chamber.
and geotechnical and geological practice, e.g.
implementation of large volumetric calculation o
f
various character, surveying of vertical mine
workings, evaluation of slope movements and
deformations on undermined territory, use in project
activities, scanning of rock samples in the laboratory
and many others.
RESUME
Knowledge of local conditions including the
strict compliance of safety regulations and ability to
p
redict the safety risks are important prerequisites fo
r
scanning in mine workings. It is important to realize,
that scanning in a mine working means demands
different amount of time and safety than in ordinary
use (e.g. while scanning the facade of a resident
b
uilding). The philosophy of the work is identical in
b
oth cases. However, there are many other external
uncontrollable factors that significantly affect the
p
ossibility of using 3D laser scanning technology and
lead to compromises and modifications of the
standard methods and procedures. It is mainly the
longer time-consumption and the environmental
conditions mentioned above, for instance the dust,
(manual reading of the band, resp. measurement by
laser distance meter) reaching the measurement errors
only in millimeters, depending on the position of the
scanner to the scanned point. The advantage of using
this technology is in ability to define the dimensions
of mine workings not only in the specified profile, but
also in any other location.
OTHER POSSIBILITIES OF APPLICATION
The technique and methods of scanning were
followed by number of other tasks. The most
noteworthy are:
the assessment of stability conditions of mine
workings on the example of repeated ceiling
overhang monitoring of huge depression named
Žebračka in the Zlaté Hory locality (Kuda et al.,
2014),
utilization of terrestrial 3D laser scanner for
monitoring of changes and deformation o
f
selected tailgate at Karviná Mine, locality Lazy
(Kajzar and Kukutsch, 2014).
Apart from the applications mentioned above,
this technology can find wide utilization in mining
V. Kajzar et al.
58
Fig. 10 Demonstration of convergence profiles.
Feng, Q.: 2012, Practial application of 3D laser scanning
techniques to undeground projects. ISRM-Swedish
national task A survey of 3d laser scanning techniques
for application to rock mechanic. BeFo Report, 114,
Stockholm, 67 pp.
Huber, D.F. and Vandapel, N.: 2003, Automatic 3D
underground mine mapping. The 4th International
Conference on Field and Service Robotics.
Jonsson, M., Bäckström, A., Feng, Q., Berglund, J.,
Johansson, M., Ivars, D.M. and Olsson, M.: 2009,
Studies of factors that affect and controls the
excavation damaged/disturbed zone (R-09-17). ÄSPÖ
Hard Rock Laboratory. Svensk Kärnbränslehantering
AB, 312 pp.
Kajzar, V. and Kukutsch, R.: 2014, Utilization of terrestrial
3D laser scanner for monitoring of changes and
deformation of tailgate No 40 703-1A at Karvina
Mine, locality Lazy. Proceedings of 5th International
Colloquium on Geomechanics and Geophysics.
Institute of Geonics AS CR, Ostrava.
Kuda, F., Kajzar, V., Divíšek, J. and Kukutsch, R.: 2014,
Application of the terrestrial laser scanning in
geoscience research (in Czech). Institute of Geonics
AS CR, Ostrava, 53 pp.
Somervuori, P. and Lamberg, M.: 2009, Modern 3D
p
hotogrammetry method for rock mechanics,
geological mapping, 3D model and documentation o
f
open pit faces and tunnels. WSP Group, 16 pp.
Středa, V.: 2011, 3D basic motorway map – The
Klimkovice tunnel. Tunel, 20, No. 4, 86–91, (in
Czech).
Štroner, M., Pospíšil, J., Koska, B., Křemen, T., Urban, R.,
Smítka, V. and Třasák, P.: 2013, 3D scanning
systems. Czech Technical University, Prague. 396 pp.,
(in Czech).
Vaníček, M., Chamra, S., Jirásko, D., Macháček, J.,
Vaníček, I., Záleský, J., Hada, A., Chaiyasarn, K. and
Soga, K.: 2012, Methods of monitoring of metro
lining in Prague. Geotechnical Aspects o
f
Underground Construction in Soft Ground.
Proceedings. 2012 CRC press, 1082 pp.
Vranka, V. and Kukutsch, R.: 2011, Problems o
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redevelopment of Zlaté Hory ore district. Proceedings
of Mining Příbram in science and technics conference,
(in Czech).
Xiling, L., Xibing, L., Comber, A. and Kewei, L.: 2011,
Underground cavity 3D detection using laser system
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humidity, spatial limitations such as the shape of mine
workings and location of mining technology. It results
in relatively accurate measurements with minimal risk
despite of staying in such complicated conditions.
It should be also pointed out, that the authors are
fully aware that the used device is not primarily
designed for direct using in mines and in similarly
hard terrain and climatic conditions. Its use in those
extreme conditions was accompanied by series o
f
preventive precautions (preventing the penetration o
f
the dust into the device, condensation on the device,
etc.) to eliminate the possibility of breaking the device
accompanied by high degree of vigilance of handling
the device itself.
Based on this experience and despite o
f
described limitations we strongly believe, that with
the current development boost of technology, the 3D
scanning will become common technique used in
mining, geotechnical and geological practice.
ACKNOWLEDGEMENT
This article was written in connection with
a project of the Institute of Clean Technologies for
Mining and Utilization of Raw Materials for Energy
Use – Sustainability Program, reg. no. MSMT
LO1406, which is supported by the Research and
Development for Innovations Operational Programme
financed by the Structural Funds of the Europe Union
and the state budget of the Czech Republic.
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scanning in drill and blast tunnels. Tunnelling and
Underground Space Technology, 25, 614–628.
... Terrestrial laser scanning 3D has become a widely used surveying method in the mining site [17][18][19][20][21]. TLS offer many possibilities in the field of terrain deformation monitoring, mainly due to the high spatial resolution and data capture speed, which makes it possible to repeat measurements to collect data in high resolution [6,18,20]. ...
... Though large-sized the mine, it is possible to determine changes in the surface area and calculating the volume of rock masses in a relatively short time. There are examples in the literature of using 3D terrestrial laser scanners to provide information of a potential unstable subsoil detection, assessment of the grading structure performance, which includes identification of slope instabilities and/or evolving failure mechanisms [14][15][16][17][18][19][20][21][22][23][24][25][26]. Inter alia in platinum mines Mogalakwena and Potgietersrust Platinums Ltd (PPRust) in South Africa the TLS method, along with special software dedicated to open pit mines, is used to monitor pits and slope management [23,24]. ...
Article
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In open pit mines the aspect of preventing and forecasting the threat of landslides and rock falls is crucial issue because of the significant consequences that instabilities may have. Systematic slope stability monitoring is necessary to ensure safe and continuous mining operations. The development of innovative technologies, such as 3D laser scanning, opens up new possibilities, especially in the case of large and hard-to-reach areas, such as open pit mines. Terrestrial laser scanners (TLS) provide fast, efficient, detailed, and accurate three-dimensional data. The article discusses the use of 3D terrestrial laser scanning method to monitor slope displacements and landslides in open pit mines. The first part of the article discusses the risk scale of gravitational displacement on the slopes, on examples of Polish open pit mines, and introduces the most common slope monitoring methods. Then, the principles of 3D terrestrial laser scanning were defined, and some examples of TLS applications in the open pit mines were presented.
... In contrast to the image processing method, which extracts characteristics from the color or brightness of pixels in the two-dimensional images, the method based on point cloud processing deals with a set of three-dimensional point coordinates [21,22]. It means that this method can achieve more accurate data acquisition and three-dimensional measurement of object surface [23][24][25]. ...
Article
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Real-time and accurate longitudinal rip detection of a conveyor belt is crucial for the safety and efficiency of an industrial haulage system. However, the existing longitudinal detection methods possess drawbacks, often resulting in false alarms caused by tiny scratches on the belt surface. A method of identifying the longitudinal rip through three-dimensional (3D) point cloud processing is proposed to solve this issue. Specifically, the spatial point data of the belt surface are acquired by a binocular line laser stereo vision camera. Within these data, the suspected points induced by the rips and scratches were extracted. Subsequently, a clustering and discrimination mechanism was employed to distinguish the rips and scratches, and only the rip information was used as alarm criterion. Finally, the direction and maximum width of the rip can be effectively characterized in 3D space using the principal component analysis (PCA) method. This method was tested in practical experiments, and the experimental results indicate that this method can identify the longitudinal rip accurately in real time and simultaneously characterize it. Thus, applying this method can provide a more effective and appropriate solution to the identification scenes of longitudinal rip and other similar defects.
... More accurate determination of accuracy is the matter of repetitive and comparative measurements and statistical evaluations. However, the range in millimetres is more than adequate for the wide-variety of utilization requesting the accuracy in centimetres (Kajzar, Kukutsch, & Heroldov a, 2015). ...
... They have been successfully applied to volumetric measurements of stockpiles in surface mining [38] and haul truck load volume estimation [39]. Kukutsch et al. [40] and Kajzar [41] studied TLS application for convergence measurement of gates in an underground mine, while the latter additionally evaluated feasibility of TLS application for e.g., deformation modelling and 3D modelling for documentation purposes. Zeng et al. [42] applied laser scanning to estimate the volume of bulk material, transported by the belt conveyor. ...
Article
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Usually, substantial part of a mine haulage system is based on belt conveyors. Reliability of such system is significant in terms of mining operation continuity and profitability. Numerous methods for conveyor belt monitoring have been developed, although many of them require physical presence of the monitoring staff in the dangerous environment. In this paper, a remote sensing method for assessing a conveyor belt condition using the Terrestrial Laser Scanner (TLS) system has been described. For this purpose a methodology of semi-automatic processing of point cloud data for obtaining the belt geometry has been developed. The sample data has been collected in a test laboratory and processed with the proposed algorithms. Damaged belt surface areas have been successfully identified and edge defects were investigated. The proposed non-destructive testing methodology has been found to be suitable for monitoring the general condition of the conveyor belt and could be exceptionally successful and cost-effective if combined with an unmanned, robotic inspection system.
... Especially, the application of laser scanning technology is used to verify spatial changes of underground mining works, to assess stability conditions of mining workplaces [2], to detect large-scale deformation [3], and to monitor the strata surface displacements during and after mining [4]. A laser scanner is also a powerful tool for classification, identifying, and recording the condition of coal rocks, which is beneficial to mine safety [5], [6]. ...
Article
During the mining operation, it is a critical task in coal mines to significantly improve the safety by precision coal mining sorting and rock classification from different layers. It implies that a technique for rapidly and accurately classify coal/rock in-site needs to be investigated and established, which is of significance for improving the coal mining efficiency and safety. In this letter, a novel instrument, a 91-channel hyperspectral LiDAR (HSL) using an acousto-optic tunable filter (AOTF) as spectroscopic device is designed, which operates based on wide spectrum emission laser source with 5 nm spectral resolution to tackle this issue. The spectra of four types coal/rock specimens collected by HSL are used to classify with three multi-label classifiers: Naive Bayes (NB), Logistic Regression (LR) and Support Vector Machine (SVM). Furthermore, we discuss and explore whether Gaussian fitting (GF) method and calibration with reference white board (RB) can enhance classification accuracy. The experiment results show that, Gaussian fitting technique not only improve the accuracy of range measurement but also optimize the classification performance using the spectra collected by the HSL. In addition, calibration with RB can improve classification accuracy as well. Additionally, we also discuss methods to improve the calibration-free classification accuracy preliminarily.
... In the registration process, they are control points of threedimensional transformation of coordinates (translation and rotation) from many local systems to one global coordinate system [5]. In the registered point cloud, precise dendrological [33], building [34] and mining [35] surveys are performed. Terrestrial laser scanning is also widely used in environmental changes monitoring in a broad sense [36]. ...
Article
Terrestrial laser scanning is currently the most effective spatial data acquisition system in terms of accuracy and the speed of measurement. Through direct measurement the laser scanning allows to determine the shape of constructions, whose assessment of displacements and deformations of the structure plays a key role in the process of technical maintenance. For this reason, it can serve as a technology of conducting integrated monitoring. In this context mathematical foundations of cartography can be incorporated not only to allow the presentation of the surface shape, but also the construction deformation process. The paper proposes a point cloud projection of an object with a finite number of symmetry planes using a terrestrial laser scanner. The range of application includes symmetrical objects, such as spherical or cylindrical tanks, cooling towers, chimneys, etc. The achieved results significantly extend the possibility to evaluate displacements, deformations and additional technical condition assessment.
Article
Mining cultural monuments are very popular in the Czech Republic, and after the period of the mining activity reduction in the 1990s, when tens of mines were permanently closed, mining monuments are the last witnesses to mining activities in the areas. These are monuments of types of mine buildings, mining towers, and galleries. However, a monument that is beyond this list is the Žebračka Mine—a local sinkhole located in the Moravian-Silesian Region in the cadastral area of the municipality of Heřmanovice, but historically belonging to Zlaté Hory. It is not an old monument, but since it is a local sinkhole, it is changing as a result of weathering when the rock falls from the overhang and the side of the mine. Since 2013, the mine has been monitored by 3D laser scanning, and since 2003 by seismological monitoring. This monitoring proves that it is still a living monument. The study evaluates a unique data series of registered seismic events related to the effect of the rockfalls covering the period of 16 years. The mutual confrontation of seismological data with atmospheric conditions, namely, outside air temperatures and precipitation, enabled to reveal the long-term development of the rockfall activity and to determine the influence of specific atmospheric parameters. The results show that the most extensive rockfall activity occurs at temperatures oscillating around the freezing point and is thus primarily related to the freezing and thawing of water in fissures of weathered parts of the rock mass. Understanding these processes is essential for forecasting the possible development of the sinkhole in the coming decades and for all other planned activities at the site related to its opening to tourists. In addition, the knowledge gained from the research will provide valuable information for educational purposes for visitors to the site, to understand the weathering processes taking place there, and to understand the behaviour of the geological environment in the given climatic conditions. Moreover, visitors will learn about current methods of monitoring the stability of the rock mass in situ. The planned opening of the sinkhole to tourists will be reflected in the increasing attractiveness of the region and will attract many enthusiasts in the field of mining history and geology, not only from the Czech Republic but also from nearby Poland.
Article
Point cloud produced by using theoretically and practically different techniques is one of the most preferred data types in various engineering applications and projects. The advanced methods to obtain point cloud data in terrestrial studies are close range photogrammetry (CRP) and terrestrial laser scanning (TLS). In the TLS technique, separated from the CRP in terms of system structure, denser point cloud at certain intervals can be produced. However, point clouds can be produced with the help of photographs taken at appropriate conditions depending on the hardware and software technologies. Adequate quality photographs can be obtained by consumer grade digital cameras, and photogrammetric software widely used nowadays provides the generation of point cloud support. The tendency and the desire for the TLS are higher since it constitutes a new area of research. Moreover, it is believed that TLS takes the place of CRP, reviewed as antiquated. In this study that is conducted on rock surfaces located at Istanbul Technical University Ayazaga Campus, whether point cloud produced by means photographs can be used instead of point cloud obtained by laser scanner device is investigated. Study is worked on covers approximately area of 30 m × 10 m. In order to compare the methods, 2D and 3D analyses as well as accuracy assessment were conducted. 2D analysis is areal-based whereas 3D analysis is volume-based. Analyses results showed that point clouds in both cases are similar to each other and can be used for similar other studies. Also, because the factors affecting the accuracy of the basic data and derived product for both methods are quite variable, it was concluded that it is not appropriate to make a choice regardless of the object of interest and the working conditions.
Conference Paper
This paper looks at innovative new methods in the capture of high quality three-dimensional (3D) information from historical artifacts and the processes needed to convert this detailed historical data into digital interactive experiences that open up new knowledge. The forensically accurate scan details, ideal for preservation and archaeology, are applied for use in developing engaging interactive entertainment outcomes, in the form of VR/AR and games. Early Aboriginal trackways discovered at the Willandra Lakes World Heritage Site in New South Wales were used as a case study to examine the methods available to accurately record these oldest footprints ever found in Australia and how to best communicate this information as an interactive visitor experience. The technical challenges involved in converting for interactive systems, and the work-flows needed are outlined as a mechanism for application in a wider range of virtual heritage experiences.
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The present work is part of a series of activities involving different skills, in order to explore and document in detail one of the most visited caves in Liguria Region. In this context, in addition to speleologists, geologists, videographers, the geomatic expertise has also been involved to carry out a laser scanner survey, in order to produce a three-dimensional model of the two more easily accessible rooms of the cave. The survey was carried out using Z+F IMAGER® 5010 instrument and the post processing operations related to registration of point clouds have been made with Z+F LaserControl®. Subsequently, two different free and open source software were used: MeshLab, to merge the point clouds and to obtain the final mesh, and CloudCompare, to make filtering on the previous results and to extract sections.
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The publication is focused on technology HDS (High Definition Surveying) which enables fast collection of precise 3D spatial data using terrestrial laser scanner. The text presents author's own experience with the use of the pulse-based scanner Leica ScanStation C10. There are described preliminary results of the geoscience research at the Institute of Geonics AS CR. Presented publication is addressed to the wide audience of geographers and geologists who are interested in new possibilities of application of geodesic measurement.
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The 3D surveying of two big cavities with very complex shapes in the Dachstein Southface Cave, Styria, Austria, serves as an example to demonstrate the efficiency of exact coordinate registration in caves by means of laser scanning. The surveyed cave is not open to the public and classified as difficult. The complicacy of a suggestive visualisation of such complex cavities is shown using the so-called Ramsau Dome as an example. Digital animations are considered the only possibility to adequately visualise such cave systems. During a surveying campaign of several days the Riegl Z-420i laser scanner worked reliably as data acquisition instrument despite the extreme conditions regarding temperature, air humidity and dirt. The generated point cloud models represent the presently best data bases for application modelling like for well discharges in karst hydrology and photo-realistic visualisations. German Am Beispiel der Vermessung von zwei mächtigen und formmäßig komplexen Hohlräumen in der Dachsteinsüdwandhöhle, Steiermark, Österreich, wird das Potential für deren Formerfassung mittels Laser-Scanner erläutert. Die Höhle ist nicht für die Öffentlichkeit zugänglich und gilt als schwer begehbar. Anhand des so genannten Ramsauer Doms wird die sehr schwierige graphische Darstellung solch komplexer Hohlräume demonstriert und als einzige Möglichkeit für eine adäquate Visualisierung die digitale Animation erkannt. Der eingesetzte Laser-Scanner Riegl LMS Z420i hat sich unter extremen Bedingungen hinsichtlich Temperatur, Luftfeuchtigkeit und Schmutz während des mehrtägigen Einsatzes als Datenerfassungsinstrument bewährt. Die letztendlich entstandenen Punktwolkenmodelle stellen die bislang besten Datengrundlagen für verschiedene Applikationsmodellierungen, wie z. B. für Quellschüttungen in der Karsthydrologie und fotorealistische Visualisierungen, dar.
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For several years, our research group has been developing methods for automated modeling of 3D environments. In September, 2002, we were given the opportunity to demonstrate our mapping capability in an underground coal mine. The opportunity arose as a result of the Quecreek mine accident, in which an inaccurate map caused miners to breach an abandoned, water-filled mine, trapping them for several days. Our field test illustrates the feasibility and potential of high resolution three-dimensional (3D) mapping of an underground coal mine using a cart-mounted 3D laser scanner. This paper presents our experimental setup, the automatic 3D modeling method used, and the results of the field test. In addition, we address issues related to laser sensing in a coal mine environment.
Article
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methods for automated modeling of 3D environments. In September, 2002, we were given the opportunity to demonstrate our mapping capability in an underground coal mine. The opportunity arose as a result of the Quecreek mine accident, in which an inaccurate map caused miners to breach an abandoned, water-filled mine, trapping them for several days. Our field test illustrates the feasibility and potential of high resolution three-dimensional (3D) mapping of an underground coal mine using a cartmounted 3D laser scanner. This paper presents our experimental setup, the automatic 3D modeling method used, and the results of the field test. In addition, we address issues related to laser sensing in a coal mine environment.
Article
Safe and precise cavity detection, especially of dangerous or inaccessible voids, is essential to safe production in a working mine. Conventional underground cavity detection methods are briefly reviewed and their limitations discussed. Accurate 3D laser measurement systems are introduced. One of these laser systems was used to detect inaccessible underground cavities from the surface through boreholes at Luanchuan molybdenum open pit in China. The results from the scanner demonstrated very well the detailed level of information that can be collected in a cavity using this method, with the cavities' layout under various benches being fully mapped. The processed data can be imported into existing models in SURPAC and CAD and the roof and floor elevations from the model of the cavity was used to output sections which would be required at a later design stage. A minimum number of exploration boreholes can be coordinated based on the scanned data which therefore not only fully details the extent of the cavity, but also saves on the costs of exploration drilling. Finally, the advantages and disadvantages of laser detection systems are analysed, and a combination of laser scanning techniques and conventional survey methodology is proposed to detect these unknown underground cavities.
Article
Three-dimensional laser scanning (Lidar) techniques have been applied to a range of industries while their application to the geological environment still requires development. Lidar is a range-based imaging technique which collects a very accurate, high resolution 3-dimensional image of its surroundings. While the use of Lidar in underground environments has been primarily limited to as-built design verification in the past, there is great value in the scan data collected as the excavation advances. The advantages of employing a static Lidar system for geotechnical and operational applications have been demonstrated at a drill and blast tunnel operation at the Sandvika–Asker Railway Project near Oslo, Norway as well as in two other test tunnels in Oslo. The increased scanning rate of newer systems makes it possible to remotely obtain detailed rockmass and excavation information without costly delays or disruption of the construction workflow with a simple tripod setup. Tunnels are non-traditional environments for laser scanners and add limitations to the scanning process as well as the in-office interpretation process; these are discussed. Operational applications of the data include: calculation of shotcrete thickness, as-built bolt spacing, and regions of potential leakage. The authors find that Lidar data, when correctly interpreted, can also provide detailed 3-dimensional characterization of the rockmass. Geometrical characterization of discontinuity surfaces including location, orientation, frequency and large-scale roughness can be obtained. Discontinuity information may be synthesized for a much more representative geomechanical understanding of the rockmass than was previously impossible with traditional hand mapping limited by face accessibility. The alignment of Lidar scans from successive exposed faces offers additional interpretation and recording advantages, particularly where shotcrete is subsequently applied behind the face. In aligning scans, larger scale features can be readily identified and rockmass trends over several rounds may be identified. Discontinuity geometries and characteristics may be input into kinematic and numerical models for further analysis.
10 Demonstration of convergence profiles
  • Fig
Fig. 10 Demonstration of convergence profiles.