epochs. Rece software desi
tunnels have b As far as m
images has be
Crosta, 1997 extracted an
operations, w Hadjigeorgiou
particularly im discontinuity
required in di disturbance o
discontinuity p of a DSM hav
geological sur Forlani, 2005;
The system de dimensional r
walls and cei however, shor
with the excav 12 m mining
with a height the total heigh
Using a TLS acquisition tim
object sampli should be ach
Indeed, the on setting TLS st
setting the inst some instrume
15 minutes per Photogrammet
problem: imag digital camera
number of the the images ar
geologists sho significantly r
successive sta model.
In particular a photographic
allowing easy and allowing,
specifications the DSM.
As far as im intervention o
and DSM re Motion SfM
adapted to mak the same prod
the gallery is aspects, whic
scientifically treated in the n
2.1 Image ac
The device de made of a dig
ently commerc igned for the
been produced mapping the di
een used for s ; with image
nd measured where lighting
u and Lemy, mportant in stab
surfaces are al iscriminating st
of blasting an planes by segm
ve been propos rvey of open p
Slob et al, 200
2. SYSTEM
eveloped is bor reconstruction
ilings of excav rt acquisition t
vation operation g tunnels wide
of 3 to 5 meter ht of the tunnel i
in such enviro mes compare to
ing resolution hieved on the v
nly way to comp tations at very
trument, orienti ents, for data ac
r station, even t try is therefore
ge acquisition a is much easi
e photo stations re minor if co
ould perform; reduce the tim
ages of data
a prototype of or topograph
y movement of at the same t
granting the re mage data ana
of human oper stitution, prop
and Dense Ma ke these phases
duct obtainable produced in sh
ch are proba significant co
next section.
cquisition devi
eveloped for fas gital camera, a
cial close-rang generation of
Somervuori scontinuities tr
ome time Tso
processing te automatically
g conditions 2005. Disco
bility analysis lways very sm
tructural discon nd excavation.
mentation of poin sed and used f
pits and rock f 05
M DESCRIPTI
rn with the aim of the detail o
vation vaults an times to not i
ns. The gallerie e with approxim
rs supporting a is thus between
onment require o photogramme
and minimiza very irregular su
ply with such re short distances
ing the scans, a cquisition: over
to an experienc considered a b
is usually very ier than a heav
s is high, the tim ompared to the
the system de me of in situ
processing the f a panoramic
hic tripod ha f equipment di
time, to meet equired accurac
alysis is conce ators during th
rietary develop atching DM a
s completely au by TLS a high
horter times and ably the mos
ntribution of
ce
st and effective a laser pointer
ge photogramm f digital mode
Lamberg, 2009 races is conce
outrelis et al., chniques trace
y in undergr can be contr
ontinuity trace of tunnels sinc
mall and expert ntinuities due t
. Determinatio nt clouds or an
for some time i faces Roncella
ION
of allowing a t of the whole t
nd facade requ nterfere excess
s are considered mately vertical
a semi-circular v n 7 and 11 mete
es much longer etry, if uniform
ation of occlu urface of the tu
equirement wou s; this takes tim
as well as, at lea rall, no less tha
ed operator. etter approach t
y fast and mov vy TLS; even
me required to e other analysi
eveloped is ab survey, assignin
e restitution o head mounted
as been deve igital reflex cam
the block geom cy and resoluti
erned, to limi he block orient
ped Structure algorithms have
utomated. In this h resolution DS
d at low costs. T st technically
the paper, wi
image acquisit and a photogr
metric els of
9. erned,
1990; es are
round rolled
s are ce the
tise is to the
on of nalysis
in the a and
three- tunnel
uiring, sively
d 8 to piers
vault: ers.
r data mity in
usions unnel.
uld be me for
ast for an 10-
to the ving a
if the shoot
is the ble to
ng to of the
on a eloped
mera metry
ion of it the
ntation from
e been s way
SM of These
and ill be
tion is raphic
tripo came
to ro stops
steps cons
The proje
symm rotat
posit cross
imag a tun
made
Fig Once
long figu
pred od with a panor
era at an approp otate the camera
s allows the ro s, designed to
ecutive shots s tripod is pos
ection center is metry of the tun
tion of the dev tion, by moving
s on the excav ging geometry f
nnel section f e of slightly ov
gure 1. Image s e the transvers
itudinal base l ure 1.b. The n
efined percenta ramic head. Th
priate elevation a around a horiz
otation of the c o maintain th
see Figure 1.a. sitioned in su
s approximately nnel. The laser
vice, help to s g the head until
vation front tha foresees the acq
from pier to pi erlapping imag
sequence acquis the excavatio
al strip is shot ength and acq
new one overla age. A longitudi
he tripod is set n from ground; t
zontal axis by 1 camera by pred
he desired ov uch a way tha
y in the longitu pointer, aligne
set the tripod l the laser spot
at marks the tu quisition from
ier, excluding ges side lap.
sition along the on front
t, the tripods m quires a new tr
aps with the p dinal strip is the
to position the the head allows
80°; a series of defined angular
verlap between at the camera
udinal plane of ed to the axis of
in the correct is on a painted
unnel axis. The each station of
the pavement
a
b
c tunnel and at
moves on by a ransversal strip
revious by the refore made by
e s
f r
n a
f f
t d
e f
a p
e y
XXII ISPRS Congress, 25 August – 01 September 2012, Melbourne, Australia
298
all images acquired from the same stop of the rotation device from the different stations along the tunnel axis. Once the
recently excavated section of the tunnel is surveyed, the excavation front is also surveyed by a minimum of three images
figure 1.c. Once a new section is cleared after the blast, reference marks
are painted on the piers and surveyed to check the progress of the drilling machine according to plan. They can easily be
recognized in the image sequence and therefore used as control points for the orientation of the block of strips. This allows the
progressive georeferencing of blocks along the tunnel, consistent with the tunnel reference system, without additional
survey work that may interfere with the excavation. 2.2 Image block design and simulation
In a preliminary stage a simulation has been carried out to test the feasibility of the method. A tunnel section 10 m long, 8 m
wide and 7.2 m high with rough surfaces has been generated in a virtual environment and draped with a photorealistic texture.
This is roughly the amount of advance after each blast in the mining tunnel under study. Finally, artificial illumination
reproducing the one available on site has been introduced. The synthetic block is made of three transversal strips with
longitudinal baselenght of 2.1 m; the survey of piers and vault is completed by 6 images spaced by 36°. Overall, therefore, the
block is made of 6 longitudinal strips of 2 models each, plus 3 images of the front.
Synthetic images were generated and processed according to the pipeline described in the next section; an artificial DSM has
been generated by image correlation. The results, though clearly obtained under ideal conditions, allowed to draw useful hints for
the realization of the panoramic head and the strong influence of rock texture and illumination on the outcome.
3. IMAGE PROCESSING DESCRIPTION 3.1 Image block orientation
