35
S e an PLATTNER(*) & Ma kus GSCHWIND(**)
(*)Ge man Ae ospace Cen e (DLR) - Remo e Sensing Technology Ins i u e, Obe p a enho en - Wessling, Ge many
(**)Ba a ian S a e O ice o Monumen P o ec ion - Weißenbu g i.Bay, Ge many
Co esponding au ho : s e an.pla ne @dl .de
EXPLORING THE UNESCO WORLD HERITAGE PROPERTY IN THE
SHALLOW WATERS AT ROSE ISLAND USING UNMANNED SURFACE VEHICLES (USV)
EXTENDED AbSTRACT
Le acque poco p o onde in o no all’Isola delle Rose, nel Lago di S a nbe g in Ge mania, anno pa e del si o Pa imonio dell’Uma-
ni à dell’UNESCO “Abi azioni pala i icole p eis o iche a o no alle Alpi”. Nell’ambi o del p oge o TRIQUERTA, inanzia o dal p o-
g amma di ice ca e inno azione dell’UE “Ho izon Eu ope” (GA No. 101094818), è uno degli o o si i pilo a pe lo s udio dei ischi
del cambiamen o clima ico sul pa imonio cul u ale. I es i a cheologici di ques ’a ea isalgono ino al Medio Neoli ico, con i pe iodi
di massimo s iluppo dell’a i i à di insediamen o p eis o ico du an e due asi dell’E à del B onzo. Inol e, gli ul imi es i no i di pala-
i e a o no alle Alpi p o engono p op io dall’Isola delle Rose. Poiché manca a una mappa ba ime ica su icien emen e a idabile e
de aglia a delle acque in o no all’isola, e in ce ca di un app occio e icace pe documen a e la posizione, l’es ensione e lo s a o delle
ampie s u u e in legno p esen i sul ondale lacus e, nel 2023 e nel 2024 sono s a e condo e ispe i amen e una campagna sona e una
campagna o og amme ica dal Cen o Ae ospaziale Tedesco (DLR).
Du an e la campagna del 2023, i da i sona lungo anse i con una dis anza a le linee di 10 m e una lunghezza o ale di 60 km sono
s a i accol i da un eicolo di supe icie senza equipaggio (USV) e as o ma i in una mappa ba ime ica de aglia a del si o Pa imonio
dell’Umani à dell’UNESCO, comp ese le sue zone cuscine o adiacen i. Ques a mappa app esen a una iso sa ines imabile pe ogni ul e-
io e la o o di esplo azione e p o ezione del si o e cos i uisce un impo an e se di geoda i pe il sis ema di suppo o alle decisioni (DSS) e il
WebGIS che sa anno implemen a i nell’ambi o di TRIQUETRA. Du an e una campagna o og amme ica nell’es a e del 2024, u ilizzando
una elecame a mon a a sulla pia a o ma mul i-s umen o senza equipaggio LimnoVIS del DLR, sono s a e accol e ci ca 15.000 immagini
e icali ad al a isoluzione e p ecisamen e localizza e del ondale lacus e icino alla pun a no d-es dell’Isola delle Rose.
Ques ’a ea con iene una densi à ele a a di a i che sono espos e all’acqua in una zona mol o poco p o onda, essendo una delle pa i
più in e essan i ma anche più ulne abili del pa imonio cul u ale. Dalle immagini, sca a e da una posizione della elecame a appena
so o la supe icie dell’acqua, sono s a i gene a i modelli 3D ad al a isoluzione e ex u e del ondale lacus e e dei es i in legno, u iliz-
zando il me odo s uc u e- om-mo ion (S M) pe un’a ea di ci ca 1150 m².
Ques i modelli o niscono in o mazioni p ecise sulla posizione, le dimensioni e lo s a o a uale dei epe i a cheologici sul ondale
lacus e e possono esse e u ilizza i pe s udia e app o ondi amen e i es i che al imen i sa ebbe o accessibili solo ai subacquei. Le cam-
pagne ipe u e po ebbe o i ela e i assi di e osione e accumulo dei sedimen i e il p ocesso di deg adazione dei epe i nel empo, sup-
po ando così lo s iluppo di misu e di mi igazione e il p ocesso decisionale igua dan e la p o ezione del pa imonio cul u ale. Inol e, i
modelli o ono un eccellen e s umen o pe la isualizzazione 3D, endendo il pa imonio cul u ale angibile pe un pubblico più ampio.
I alian Jou nal o Enginee ing Geology and En i onmen
www.ijege.uni oma1.i
IJEGE, Special Issue 1 (2025): 35-45, DOI: 10.4408/IJEGE.2025-01.S-03
E-ISSN 2035-5688 | ISSN 1825-6635 / ©Au ho (s)
36 I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
S. PLATTNER & M. GSCHWIND
AbSTRACT
Rose Island (Ge many) is pa o he UNESCO Wo ld He i age
si e “P ehis o ic Pile Dwellings a ound he Alps” and a pilo si e
o he EU unded p ojec TRIQUETRA, which a ge s he isks
o clima e change on cul u al he i age. Wi h he lack o a de ailed
ba hyme ic map o he wa e s a ound Rose Island and in sea ch
o an e icien app oach o documen ing he wooden elics om
I on Age a he lake bo om, bo h a sona and a pho og amme ic
campaign we e conduc ed by he Ge man Ae ospace Cen e (DLR).
F om he sona measu emen s, he i s eliable ba hyme ic map
o he a ea was gene a ed and p o ided o TRIQUETRA’s decision
suppo sys em and WebGIS. Du ing he pho og amme ic
su ey, ~15.000 high esolu ion images o he lake loo we e
aken by an unmanned su ace ehicle (USV) and p ocessed o
high- esolu ion 3D models by using he s uc u e- om-mo ion
me hod (S M). The models p o ide an unp eceden ed le el o
de ail o he documen a ion and examina ion o he a chaeologic
emains a Rose Island and a ascina ing insigh o he p ehis o ic
se lemen emains o he gene al public.
Keywo ds: unde wa e , pho og amme y, a chaeology, cul u al he i age,
pile dwellings, e osion, USV, 3D imaging, sona , S M.
INTRODUCTION
Roseninsel (Rose Island) is he only island in Lake S a nbe g
which is si ua ed sou h-wes o Munich (Ge many) and is
su ounded by a la ge shallow wa e zone (see Fig. 1). The island’s
special opog aphic loca ion and p obably also he esou ces o ish
and wa e bi ds a ac ed he a en ion o people ea ly on.
The ea lies piece o e idence o human p esence a Rose
Island is a single agmen o middle Neoli hic po e y ha
was ound in a summe wi h ex eme low wa e and da es
back o he i s hal o he 5 h millennium BC (Fesq-Ma in
e alii, 2019). Fu he po e y inds om he Münchshö en
Cul u e (4.300-3.900 BC) and he Al heim cul u e pe iod
(3800-3400/3300 BC) indica e he exis ence o a pe manen
se lemen on he island du ing hese La e Neoli hic pe iods.
Nume ous a chaeological inds show ha he B onze Age
was a heyday o p ehis o ic se lemen ac i i y a Rose Island.
The 17 h/16 h cen u y BC, i.e. he ansi ion pe iod om he Ea ly
o Middle B onze Age, and he middle o la e U n ield cul u e
(11 h - 9 h cen u y BC), i.e. he inal phase o he B onze Age, a e
pa icula ly well ep esen ed in he a chaeological inds om
Rose Island and he shallow wa e s a ound i (Von Schab, 1876;
Schli ze , 2023). Thus, he a chaeological inds co espond
qui e well wi h B onze Age se lemen sequences o o he lake
sho e se lemen s a ound he Alps. In con as o ha , I on Age
ounda ion beams si ua ed nex o he no heas e n ip o he island
a e e y peculia , as – da ing o he Ea ly Cel ic pe iod – hey
p o ide he la es e idence o pile dwellings a ound he Alps a all.
In he ea ly 8 h cen u y AD an ex ensi e e e men o he
sho eline was ins alled (Fiede ling e alii, 2023) and om he
Middle Ages un il he Thi y Yea s’ Wa , he island was a pilg image
des ina ion (Ahl & Pä gen, 2023). In he 19 h cen u y i inally
was ans o med in o a summe e ea o he Ba a ian kings.
When du ing he second hal o he 19 h cen u y, a e i able
“pile dwelling e e ” was ampan in Cen al Eu ope, Rose
Island was he i s and only pile dwelling si e o be disco e ed
and esea ched in Ba a ia du ing he 19 h cen u y (Von Schab,
1876; Pä gen & Schli ze , 2023).
When Rose Island became one o 111 si es in six coun ies
ha oge he o m he ansna ional se ial UNESCO Wo ld
He i age Si e “P ehis o ic Pile Dwellings a ound he Alps”,
a si e managemen was ins alled and a moni o ing sys em se
up, because a compa ison o ae ial pho og aphs om di e en
decades showed e osion in pa s o he shallow wa e zone
a ound he island (Gschwind, 2023).
In 2014, on behal o he Ba a ian S a e O ice o Monumen
P o ec ion (BLFD), he Ba a ian Socie y o Unde wa e
A cheology (BG U) ins alled 174 wooden e osion ma ke s in a
25×25 m g id, mos ly lying wi hin he Wo ld He i age p ope y (see
Fig. 1). The ma ke s’ posi ions (la i ude, longi ude, al i ude) we e
measu ed and documen ed by using RTK GNSS (BGFU, 2014).
The heigh o he sedimen ela i e o he op o his ma ke s
is measu ed and documen ed by di e s o he BG U once pe
yea , esul ing in a yea ly epo o BLFD. These epo s con ain
ma ke -by-ma ke s a is ics as well as hea maps showing he a eas
whe e e osion o accumula ion domina e. E osion/accumula ion
a es ypically lie in a ange o a ew cen ime e s wi h a maximum
Fig. 1 - O e iew o he UNESCO Wo ld He i age p ope y (g een) and
bu e zone (blue) a he wes e n sho e o Lake S a nbe g (Ge -
many). E osion ma ke s co e mainly he co e zone and a e
shown in o ange. Backg ound: Ae ial image by DLR
37
I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
EXPLORING THE UNESCO WORLD HERITAGE PROPERTY IN THE SHALLOW WATERS AT ROSE ISLAND
USING UNMANNED SURFACE VEHICLES (USV)
e osion o 14 cm and a maximum accumula ion o 7 cm since he
beginning o he moni o ing in 2014. (BGFU, 2023).
Howe e , his kind o e osion moni o ing is a ime-consuming,
labo -in ensi e and he e o e expensi e ask. Fu he mo e, he
numbe o e osion ma ke s which can’ be loca ed o p ope ly ead
inc eases, mos ly because hey o en ge co e ed by mac ophy es.
which leads o subs an ial gaps in he da ase . In 2023, only 104 o
o al 174 e osion ma ke s could be ead (BGFU, 2023).
Apa om he known posi ions and dep hs o hese e osion
ma ke s, al hough Rose Island is loca ed in o he wise well-known
wa e s, ba hyme ic de ails showing he opog aphy o he qui e
une en unde wa e e ain a ound he island a e no publicly a ailable.
In addi ion o e osion moni o ing, BG U also ca ies ou he
documen a ion o he numbe , posi ion, ype and condi ion o
a cheological s uc u es isible a he bo om o he shallow wa e s
a ound Rose Island. Due o he shee size o he a ea and he g ea
e o in ol ed in deploying esea ch di e s, his had o be limi ed
o a ge ed a eas o sol e esea ch ques ions and p o ide addi ional
in o ma ion o a be e unde s anding o he si e and i s p o ec ion.
The o e all goal o all he desc ibed onsi e moni o ing
and documen a ion ac i i ies ca ied ou wi hin he amewo k
o Wo ld He i age moni o ing is a be e unde s anding o
he p ocesses ha h ea en Rose Island as an a chaeological
Cul u al He i age si e, because his is a p econdi ion o
de eloping cus omized p o ec i e measu es and mi iga ion
s a egies o he si e. The e o e BLFD included Rose Island
as a Pilo Si e in o he Na ional esea ch p ojec SuBoLakes
(Sus ainable Boa ing on Lakes in Ge many; www.subolakes.
de) unded by he Ge man Fede al En i onmen al Founda ion,
and he in e na ional esea ch p ojec TRIQUETRA (Toolbox
o assessing and mi iga ing Clima e Change isks and na u al
haza ds h ea ening cul u al he i age; www. ique a-p ojec .eu)
unded om he EU HE esea ch and inno a ion p og amme
unde GA No. 101094818 (Gchwind e alii, 2024).
SuBoLakes analyzed he e ec s o passenge and leisu e
shipping on he shallow wa e a eas by aking measu emen s
a a ious wa e dep hs nex o he I on Age ounda ion beams
no h eas o he island and de eloped ecommenda ions
o ac ion. In con as o ha he EU p ojec TRIQUETRA
ocusses on he impac o clima e change on cul u al
He i age si es in he Medi e anean and in Cen al Eu ope.
21 o ganiza ions om se en coun ies o m he conso ium
o he p ojec wi h Uni e si ies, Resea ch O ganiza ions,
Cul u al He i age Au ho i ies and p i a e companies being
ep esen ed. Toge he hey a ge eigh pilo si es in six
coun ies wi h de ailed in e disciplina y esea ch. Two o
he pilo si es a e pa o he UNESCO Wo ld He i age Si e
“P ehis o ic Pile Dwellings a ound he Alps”. The main goal o
he TRIQUETRA p ojec is o iden i y, quan i y and minimize
he isks o clima e change o cul u al he i age si es and o
de elop a oolbox o a isk assessmen and he de elopmen
o mi iga ion s a egies o o he Cul u al He i age si es.
In he scope o TRIQETRA, bo h he lack o a su icien ly
eliable and de ailed ba hyme ic map o he wa e s a ound
Rose island as well as he sea ch o an app oach o make he
de ec ion, he measu emen and he moni o ing o he condi ion
o he wooden emnan s a he lake loo mo e e icien and, i
possible, mo e p ecise, led o wo campaigns conduc ed by he
Ge man Ae ospace Cen e (DLR).
DATA AND METHODS
Sona based ba hyme ic su ey
A i s campaign ook place a Rose Island on o ally eigh
days in July and Augus 2023 and was a sona su ey o ga he
su icien and up- o-da e dep h in o ma ion in o de o being able
o gene a e an accu a e ba hyme ic map as a undamen al geoda a
se o he use in TRIQUETRA’s Decision Suppo Sys em (DSS)
and o he isualiza ion in he p ojec ’s WebGIS.
To ga he he dep h da a o he p oduc ion o a ba hyme ic
map, DLR used i s ul a-compac (54 cm in leng h), emo ely
con olled o au onomously ope a ing sona boa “La Plancha”
(Fig. 2). I is equipped wi h a Blue Robo ics Ping single-
beam sona (115 kHz), RTK GNSS and 868 MHz long ange
communica ion o emo e con ol and eleme y. C uising
speed when conduc ing ba hyme ic measu emen s is ypically
0.8 m/s, which gi es one measu emen e e y 8 cm along- ack
a a sampling a e o 10 Hz. The boa is capable o ope a ing
up o 4 hou s wi h a ull cha ge o i s 11.1 V Li hium ba e ies.
Fig. 2 - The ul a-compac ba hyme ic su ey ehicle “La Plancha”
o DLR
38 I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
S. PLATTNER & M. GSCHWIND
Bo h he UNESCO wo ld he i age p ope y and i s bu e
zone we e su eyed by aking sona measu emen s along eas -
wes ansec s wi h a ack- o- ack dis ance o 10 m and a o al
pa hleng h o ~60 km (Fig. 3). When na iga ing on hese acks,
he boa ope a ed ully au onomously.
Only e y shallow a eas close o he sho e o Rose Island
and in he icini y o he mainland had o be su eyed by
con olling he ehicle manually, hus a oiding collisions wi h
he sho eline, he g ound o ipa ian ege a ion.
Since he campaign ook place on mul iple days, he ela i e
day- o-day changes o he wa e le el had o be moni o ed
du ing he whole imespan in o de o being able o co ec he
da a o he a ying heigh o he wa e su ace la e . This was
done by using a pole on a je y whe e he dis ance om i s op
o he wa e su ace was measu ed.
In o de o educe he la ge amoun o dep h da a in a long-
ack di ec ion, an a e age o e 5 measu emen s was applied,
esul ing in a da a poin e e y 40 cm. These da apoin s we e
isualized wi h he ba hyme y so wa e Ree Mas e and
ou lie s we e emo ed manually.
All dep h alues we e co ec ed o he e ical dis ance
be ween he wa e su ace and he ansduce o he sona (4
cm) as well as o he daily luc ua ions o he wa e le el. As
a e e ence alue, he wa e le el o he i s day o he su ey
(583.9 m abo e sea le el, measu ed using RTK GNSS nea
Rose Island) was used. All dep h in o ma ion in he de i ed
ba hyme ic map e e o his le el.
Pho og amme ic su ey o pile dwelling emains
The second campaign a Rose Island was conduc ed
on mul iple days in May, June and July 2024 and was a
pho og amme ic su ey o ga he high- esolu ion images o he
lake bo om nea he no h eas e n ip o he island, whe e a high
densi y o imbe s exposed o he wa e can be ound. The goal
o he second campaign was o ind i au oma ically ga he ed,
close- ange, high- esolu ions images can be used o gain
be e in o ma ion abou he posi ion, ype, size and condi ion
o he wooden elics o i i is possible o ob ain his kind o
in o ma ion mo e e icien ly han i can be done by di e s.
Pho og amme ic echniques ha e been used o abou
six y yea s in unde wa e a chaeology (D ap, 2012), wi h a big
inc ease in popula i y wi h he ad en o easy o use so wa e
ools based on he S uc u e- om-Mo ion (S M) echnique like
Agiso Me ashape, Pix4DMappe o OpenD oneMap. Usually,
images used o c ea ing 3D models using such ools a e aken
by di e s o by emo ely ope a ed unde wa e ehicles (ROVs).
The ac ha la ge pa s o he a chaeological emains a Rose
Island lie a dep hs a ound 0.5 - 3 m, in conjunc ion wi h he clea
wa e s o Lake S a nbe g, allows o he use o a USV equipped
wi h a came a moun ed jus below he wa e su ace o his ask.
Such a ehicle can scan he bo om o he shallow wa e in a line-
by-line su ey pa e n simila o he p ocess how an ae ial d one
collec s pho os o a digi al ele a ion model (DEM). Simila wo k
was done by Ha che e alii (2020), by using a pla o m equipped
wi h i e synch onized came as, owed by a manned boa o he
pho og amme ic mapping o co al ee s in Flo ida.
The unmanned su ace ehicle (USV) LimnoVIS (130 cm in
leng h) was de eloped a DLR as a mul i-ins umen pla o m o
he au onomous o emo ely con olled collec ion o in-si u da a
used o he alida ion o op ical sa elli e da a and p ocessing
algo i hms (Pla ne e alii, 2023). Fo he pu pose o collec ing
images du ing he TRIQUETRA pho og amme ic su ey, i was
equipped wi h a sub-su ace, down-looking came a (Fig. 4).
The came a sys em consis s o a USB compu e ision came a
based on he Sony IMX 264 global shu e 5 MP senso wi h an
RGB Baye a ay and a Fujinon HF6XA-5M ixed ocus 6 mm
wide angle lens. I is ins alled in a wa e igh enclosu e co e ed by
a hemisphe ical dome po and p o ides a ho izon al ield o iew
(FOV) o 70°. Bo h came a and lens a e moun ed on a longi udinal
aluminum ail so ha he nodal poin o he lens can be aligned
wi h he cen e o he hemisphe ic dome po in o de o minimize
dis o ions due o e ac ion a he wa e /ai in e ace (She, 2019).
The global shu e p o ides o minimal image dis o ions
caused by he mo emen o he ehicle du ing exposu e. The
came a can be igge ed manually ia he emo e con ol o
au oma ically ia he onboa d ligh con olle o LimnoVIS
which also eco ds he RTK GNSS posi ion a he exac momen
when he shu e opens. Images a e sa ed on an SSD connec ed
Fig. 3 - The ba hyme ic su ey co e ed bo h he Wo ld He i age p op-
e y (g een) and i s bu e zone (blue). A ound 60 km o su ey
acks (o ange) we e eco ded au onomously. Only a eas close
o he sho e we e eco ded by s ee ing he USV manually. Back-
g ound: Ae ial image by DLR
39
I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
EXPLORING THE UNESCO WORLD HERITAGE PROPERTY IN THE SHALLOW WATERS AT ROSE ISLAND
USING UNMANNED SURFACE VEHICLES (USV)
o an embedded Linux compu e , which also connec s he
came a sys ems o he LimnoVIS onboa d LAN and p o ides an
image se e which can be accessed o e a wi eless connec ion
o quali y con ol by he ope a o du ing ope a ion.
Fo he su ey, an a ea o ~1150 m² close o he no heas e n
ip o Rose Island was selec ed (Fig. 5), showing a high densi y
o s uc u al emains o p ehis o ic pile dwellings.
Since i was planned o use he S M so wa e Agiso
Me ashape o he c ea ion o he 3D model, images we e aken
wi h an o e lap o 80 % along- ack and 60 % ac oss- ack
acco ding o he ecommenda ions in he so wa e manual. Fo
his ask, he ehicle had o ope a e au onomously and wi h high
p ecision on ansec s wi h a ack- o- ack dis ance o 30 cm,
which esul ed om he p e ailing wa e dep h o 1 m a he ime
o he campaign, he desi ed o e lap o 60 % ac oss- ack and he
came a’s FOV o 70°. The equi ed p ecision could be achie ed
by using RTK GNSS wi h a i ual base s a ion p o ided by he
Ba a ian SAPOS-HEPS co ec ion se ice ia he mobile da a
ne wo k, ensu ing a nominal loca ion accu acy o ~1 cm. A a
c uising speed o 0.5 m/s, he along- ack o e lap o 80 % could
be achie ed by aking one pho o e e y 400 ms. The images we e
eco ded on cloudy days in o de o p e en dis u bing caus ics
which a e caused by he di ec sunligh e ac ed by he wa es
a he wa e su ace. In o de o p e en mo ion blu ing, a
maximum exposu e ime o 5 ms (1/200 s) was used.
In his way app ox. 15.000 close-dis ance, o e lapping
e ical images we e collec ed in he a ea depic ed in Fig. 5.
In o de o ge be e isualiza ion esul s, he images we e
p ep ocessed p io o he applica ion o he S M echnique. The
p ep ocessing was done wi h he open sou ce so wa e GIMP
and i s Ba ch Image Manipula ion Plugin, whe e an au oma ic
his og am s e ching and a mild inc ease o b igh ness and
sa u a ion we e applied. Figu e 6 shows a compa ison be ween
an unp ocessed, aw image as eco ded by he came a and he
same image a e i has been p ep ocessed.
Wi h he images p epa ed his way, hey we e impo ed o
Agiso Me ashape (Ve sion 2.1.1) (agiso , 2024). Fo gene a ing
3D models wi h good p ecision, i is c ucial o p o ide as much
geome ical in o ma ion oge he wi h he images as possible,
Fig. 4 - USV LimnoVIS o DLR, equipped wi h downwa d acing unde -
wa e came a in a wa e igh housing
Fig. 5 - A ea o he pho og amme ic su ey wi h LimnoVIS a he no h-
eas e n ip o Rose Island. Backg ound: Ae ial image by DLR
Fig. 6 - Compa ison o aw ( op) and p ep ocessed (bo om) unde wa-
e images om LimnoVIS came a. The images show a de ail o
he Cel ic pile dwelling emnan s nea Rose Island
40 I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
S. PLATTNER & M. GSCHWIND
whe e he mos impo an is he exac loca ion whe e each image
was eco ded. In using LimnoVIS as he ope a ing pla o m, i was
possible o associa e he RTK GNSS posi ion (nominal accu acy
1 cm ho izon ally, 2-3 cm e ically) as well as pi ch, oll and
il o he ehicle (and he e o e o he came a) as addi ional
in o ma ion wi h each image. This in o ma ion was eco ded by
he ligh con olle o each image a he exac ime o exposu e
which was accomplished by using he shu e signal o he came a
o igge ing he ligh con olle ’s posi ion logging. Addi ionally,
he h ee-dimensional posi ion o se s o he came a ela i e o he
GNSS an enna ( he so-called le e a ms) we e speci ied.
Using he auxilia y in o ma ion men ioned abo e, he images
we e aligned in Agiso Me ashape, while he unknown pa ame e s
o he came a model we e i ed simul aneously. Figu e 7 shows
exempla ily he posi ion and o ien a ion o each image how i was
calcula ed and op imised by he alignmen p ocess in Me ashape.
Fig. 7 - O ien ed came as o e he 3D model. I egula i ies in he
posi ion and o ien a ion o he came as a e due o he wa es
du ing eco ding
Fig. 8 - Resul ing high esolu ion ba hyme ic map o he UNESCO Wo ld He i age p ope y and he su ounding bu e zone a Rose Island, Lake
S a nbe g. Backg ound: Ae ial image by DLR
41
I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
EXPLORING THE UNESCO WORLD HERITAGE PROPERTY IN THE SHALLOW WATERS AT ROSE ISLAND
USING UNMANNED SURFACE VEHICLES (USV)
Mino de ia ions om he ec angula su ey pa e n, he e ical
o ien a ion and posi ion o he came a and an angula de ia ion
om he boa ’s/came a’s longi udinal axis ela i e o he d i ing
di ec ion can be no iced in Fig. 7. These de ia ions a e caused by
he wa es du ing he imaging campaign and a e easily calcula ed
and accoun ed o du ing he S M p ocessing.
In o de o u he inc ease he geome ic p ecision o he o ien ed
came as, he known posi ions o h ee e osion ma ke s lying in he
su eyed a ea we e used as g ound con ol poin s (GCPs).
RESULTS AND DISCUSSION
Sona based ba hyme ic su ey
F om he p e-p ocessed sona da a, a ba hyme ic map
was gene a ed using he so wa e Ree Mas e ( e sion 2.0)
( ee mas e , 2023) and is shown in Figu e 8. I is he i s comple e,
accu a e map a his le el o de ail and co e s bo h he UNESCO
Wo ld He i age p ope y and he su ounding bu e zone (compa e
wi h Fig. 1). I shows a p onounced opog aphy wi h Rose Island
lying on he op o one o mul iple subme ged mo aine idges da ing
back o he Las Glacial Pe iod. A p onounced channel, con aining
mul iple and dis inc oughs and wi h a maximum dep h o a ound
14 m sepa a es he island and he o he mo aine idges om he
mainland. La ge pa s a ound he island, especially o he no h
eas , show maximum wa e dep hs o only 1 - 2 m. These a eas also
con ain he highes densi y o a chaeological emains.
The indica ed dep hs e e o a wa e le el o 583.9 m abo e
sea le el a Rose Island. No e ha du ing all su eys conduc ed in
he scope o his wo k, he lake le els measu ed wi h RTK GNSS
lay 30 cm on a e age below he co esponding alues o he only
o icial lake le el gauge a he ci y o S a nbe g in a dis ance o ~7
km om Rose Island. This sys ema ic o se be ween lake le els
measu ed by RTK GNSS and he gauge a S a nbe g could no
be explained since bo h he SAPOS-HEPS se ice as well as he
gauge e e o he Ge man main ele a ion ne wo k DHHN2016.
The dep hs measu ed by he sona (Blue Robo ics Ping) we e
alida ed agains a ape measu e a 62 poin s, co e ing he whole
ange o dep hs occu ing in he a ea om 0 o 14 m. Addi ionally,
he measu emen s we e compa ed o hose o a second sona (Deepe
Chi p+) The se up o he alida ion su ey is shown in Figu e 9.
Figu e 10 shows a plo o he measu emen s o bo h sona s
agains he eadings o he ape measu e. The da a o bo h sona s
show a e y good co espondence wi h he alues ead om he
ape measu e. Since he wa e empe a u e a ec s he speed o
sound bu was no known o e he whole wa e column, a less linea
co ela ion was expec ed. Howe e , a di e o BG U epo ed
a cons an wa e empe a u e om he su ace o he maximum
dep h o 14 m, which explains he pe ec ly linea connec ion
be ween sona measu emen s and ape measu e eadings. The da a
om he BR Ping sona showed an RMSE o 0.10 m, while hose
o he Deepe Chi p+ had an RSME o 0.12 m.
I u ned ou ha possible e o s in he dep h measu emen s
due o wa e-induced pi ch/ oll mo emen s o he ehicle could
be neglec ed as he sona beam wid h o 30 deg ees eliably
deli e ed he sho es dis ance o he bo om in almos all
condi ions. Mino ou lie s we e compensa ed by he a e aging
o i e measu emen s o one da a poin .
The de i ed ba hyme ic map was p o ided o he
TRIQUETRA p ojec pa ne s in he o m o ec o da a ( o
he isoba hs) and as a GeoTIFF as e ile wi h a ho izon al
geome ic esolu ion o 1 m and a dep h esolu ion o 1 cm.
I will be inco po a ed in he TRIQUETRA DSS as well as in
he p ojec ’s WebGIS.
Fig. 9 - Valida ion o wo sona s (Blue Robo ics Ping and Deepe
Chi p+) agains a ape measu e a 62 poin s a di e en dep hs
Fig. 10 - Valida ion o wo sona s (Blue Robo ics Ping and Deepe
Chi p+) agains a ape measu e a 62 poin s a di e en dep hs
42 I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
S. PLATTNER & M. GSCHWIND
Pho og amme ic su ey o pile dwelling emnan s
F om he p e-p ocessed and o ien ed images o he Cel ic pile
dwelling emnan s a he no h-eas e n ip o Rose Island (see Fig. 5),
a ex u ed 3D model wi h a pe -pixel esolu ion o 2 mm (1 mm in he
a ea wi h he highes densi y o elics) was gene a ed wi h AgiSo
Me aShape (Fig. 11). The model shows a de ailedness and p ecision
way beyond any al eady exis ing documen a ion o his a ea.
Du ing da a p ocessing, no co e age gaps caused by
na iga ional o wa e-induced angula de ia ions occu ed since
he planned o e lap o 80% along ack and 60% ac oss- ack le
some oom o such e o s. The accu a e posi ional in o ma ion
(nominal e o 1-2cm ho izon ally) p o ided by RTK GNSS
oge he wi h he pi ch and oll angles eco ded by he ehicle’s
IMU ensu ed a p ecise calcula ion o he came a posi ion and
o ien a ion in in he S M p ocess p io o he calcula ion o he
poin cloud, hus p o iding o a closed and accu a e 3D model.
The model can be examined in 3D isualiza ion so wa e ools,
e.g. he ee AgiSo Viewe . Using he iewe s’s measu emen
ool, any dis ance, e.g. he leng h o he imbe s o he dimension
o ea u es like no ches o cu ou s can be measu ed (Fig. 12, op).
I is also possible o ead he s a e o e osion/accumula ion a each
e osion ma ke con ained in he model (Fig. 12, bo om).
In addi ion, an o homosaic o he a ea was gene a ed (Fig.
13). Like he 3D model, he o homosaic is a ailable a a esolu ion
o 2 mm/pix o he whole a ea and 1 mm/pix espec i ely o he
a ea wi h he highes densi y o wooden emains.
Howe e , he a ea co e ed by pho og amme ic me hods in
his s udy makes up o only a small pa o he 125.000 m² la ge
UNESCO Wo ld He i age p ope y. The ba hyme ic campaign
o 2023 showed ha om he o al a ea, 31 % ha e a wa e
dep h o less han 1 m, 66 % less han 2 m and 89 % less han
3 m wi h espec o a e e ence wa e le el o 583.9 m AMSL.
Obse a ions om he pho og amme ic campaign sugges
ha he maximum wa e dep h whe e he S M me hod, based
on nea -su ace image y, is easible a Lake S a nbe g is a ound
3 m unde op imal condi ions (clea wa e du ing win e and
sp ing). Thus, wi h he p esen ed echnique, i is possible o
gene a e a 3D model o nea ly 90 % o he UNESCO Wo ld
He i age p ope y a Rose Island.
Howe e , when ans e ing he me hod o o he egions, he
expec ed u bidi y o he wa e has o be kep in mind as a limi ing
ac o o he dep h up o which a pho og amme ic su ey using a
Fig. 11 - De ail om he 1 mm/pix high esolu ion ex u ed 3D model o wooden pile dwelling emains a he no heas e n ip o Rose Island, whe e
he densi y o isible a chaeological s uc u es is highes
43
I alian Jou nal o Enginee ing Geology and En i onmen , Special Issue 1 (2025) www.ijege.uni oma1.i
EXPLORING THE UNESCO WORLD HERITAGE PROPERTY IN THE SHALLOW WATERS AT ROSE ISLAND
USING UNMANNED SURFACE VEHICLES (USV)
CONCLUSION
The esul s o he sona campaign o 2023 showed excellen
quali y, bo h wi h ega d o he dep h measu emen s as well as he
de i ed ba hyme ic map. The map i sel ep esen s a aluable
asse and an ex emely impo an piece o in o ma ion o all
u he in es iga ions in ela ion o he h ea s o clima e change
like i is done wi hin he p ojec TRIQUETRA bu also o any
o he wo k in he con ex o he p ese a ion and managemen
o Rose Island as pa o he UNESCO Wo ld He i age si e
“P ehis o ic Pile Dwellings a ound he Alps”. In addi ion o ha ,
i helps he Na u e P o ec ion Au ho i ies o plan and posi ion
buoys o u he p o ec he bay o Rose Island as he mos
impo an a ea o es ing wa e bi ds in Lake S a nbe g, which
is a Ramsa We land o In e na ional Impo ance. In espec o
he a chaeological emains, simula ions o he impac o sinking
wa e le els due o clima e change can be conduc ed in he u u e
and la ge scale e osions o accumula ions can be moni o ed by
conduc ion epea ed campaigns and compa ing hei esul s.
The pho og amme ic su ey and he gene a ion o
an unp eceden ed, high-p ecision and ex u ed 3D model
showed imp essi ely he alue o his me hod o unde wa e
a chaeology. The wooden emains a he no h-eas e n ip o
Rose Island we e documen ed in a mos de ailed and isually
appealing way like i was done ne e be o e. Moun ing a came a
on an unmanned su ace ehicle (USV) o ga he ing la ge
amoun s o unde wa e images in a ela i ely sho ime p o ed
o be an e ec i e and e icien app oach in o de o collec a
su icien numbe o images o modelling la ge a eas wi h he
S M echnique. The la e p o ed once again o be an e ec i e
ool o documen ing he posi ion, size and condi ion o elics in
he ield o unde wa e cul u al he i age explo a ion. Repea ed
campaigns, ex ended o la ge a eas may help o moni o he
deg ada ion o he wooden elics exposed o he wa e o e ime,
o de elop mi iga ion s a egies, and o make decisions ega ding
p o ec ion measu es, as a mos de ailed documen a ion, e. g., is a
p econdi ion be o e a chaeological s uc u es can be co e ed o
p o ec hem om e osion o o he h ea s.
Las bu no leas , he high- esolu ion 3D models o p ehis o ic
s uc u es, such as he lying imbe s om he Ea ly Cel ic pe iod,
o e ascina ing possibili ies o communica ing he in isible
Wo ld He i age o a b oade public, which is an impo an pilla o
he Wo ld He i age p o ec ion concep o Rose Island. Cu en ly
DLR is p epa ing a i s use o he da a o media ion as pa o
he upcoming special exhibi ion “Leben un e Wasse ” (Li e unde
Wa e ) o Museum S a nbe ge See, S a nbe g (Ge many). In
addi ion, he 3D model could be used as pa o an XR Expe ience
ha b ings he in isible Wo ld He i age o li e o isi o s o he
small museum on he island wi h he help o 3D glasses, o simply
as an imp essi e 3D model ha isi o s can explo e hemsel es ia
a sma phone o a web applica ion on hei mobile de ices.
USV is easible. Highe u bidi y will cause a lowe image con as
which in u n will lead o a lack o image- o-image ma ching
poin s which a e c ucial in he S M p ocess. Image ea u es
which don’ s and ou op ically om he backg ound, a gene al
lack o ea u es o epea ed pa e ns o simila ea u es (e.g.
egula ly shaped ipples in a sandy bo om) will also complica e
he iden i ica ion o ma ching poin s and he e o e lead o a lowe
quali y poin cloud and 3D model. A sys ema ic examina ion o
he e ec s o u bidi y o image con as in gene al wi h espec
o he usabili y o his me hod was no in he scope o his wo k.
Fig. 12 - Measu ing dis ances in he 3D using Agiso Me ashape.
Top: De ail o a cu ou in a sill ame. Bo om: Reading he
heigh o an e osion ma ke
Fig. 13 - O homosaic o he a ea co e ed by he S M su ey a a
esolu ion o 2mm/pix
