RESEARCH ARTICLE
3D geome ic su ey o cul u al he i age by UAV in
inaccessible coas al o shallow aqua ic en i onmen s
Ma iluz Gil-Docampo
1
| Sim
on Peña-Villasenín
1,2
| Ana M. S. Be encou
2
|
Juan O iz-Sanz
1
| Sa a Pe aleda-Vázquez
1
1
Ag o o es y Enginee ing Depa men ,
Uni e si y o San iago de Compos ela, Highe
Poly echnic School o Enginee ing, Lugo, Spain
2
Landscapes, He i age and Te i o y
Labo a o y (Lab2PT); His o y Depa men ,
Uni e si y o Minho, B aga, Po ugal
Co espondence
Sim
on Peña-Villasenín, Ag o o es y
Enginee ing Depa men , Uni e si y o
San iago de Compos ela, Highe Poly echnic
School o Enginee ing, Lugo, Spain.
Email: [email p o ec ed]
Funding in o ma ion
Xun a de Galicia
Abs ac
Cul u al he i age in coas al o shallow aqua ic en i onmen s is o en loca ed in a eas
whe e access is di icul o whe e accu a e su ey and documen a ion may no
always be possible wi h e es ial o aqua ic equipmen . The combina ion o pho o-
g amme y and unmanned ae ial ehicles (UAVs) gene a es a ange o possibili ies
ac oss mul iple sec o s, including his o y, e hnog aphy and cul u al he i age s udies.
Addi ionally, hese me hods can be used o p ospec new a chaeological si es. This
a icle p esen s h ee case s udies ha use UAV echniques and S uc u e om
Mo ion and Mul i iew S e eo (S M-MVS) pho og amme y o conduc opog aphic
and geome ic egis a ions o a chaeological, his o ical and e hnog aphic si es (some
o which a e classi ied as cul u al he i age si es). These examples a e loca ed in
coas al o shallow aqua ic en i onmen s ha a e di icul o su ey wi h adi ional
me hods. The esul s show ha i is possible o ca y ou de ailed geome ic egis a-
ion and he i age p ospec ion o e la ge coas al o shallow aqua ic en i onmen s
using a low-cos UAV. Fu he mo e, he esul s o his wo k show g ea ad an ages
in e ms o cos and quali y, e en in cases whe e he seabed is below a shallow wa e
column. O he pa icula i ies o S M-MVS applica ion in aqua ic en i onmen s a e
discussed. F om an in e disciplina y pe spec i e, his me hodology will o e new
possibili ies o he s udy, es o a ion and conse a ion o a chaeological, his o ical
and e hnog aphic monumen s.
KEYWORDS
3D modelling, ae ial p ospec ing, close- ange pho og amme y, cul u al he i age
1|INTRODUCTION
A ho ough examina ion o he isual, spa ial and opog aphic eco ds
is c i ical o ensu ing he accu a e s udy, conse a ion and
dissemina ion o cul u al he i age a chi ed wi hin coas al o shallow
aqua ic en i onmen s. The adi ional me hodologies used o hese
examina ions ha e been pa ially eplaced in ecen decades by la ge
da a acquisi ion echniques such as e es ial lase scanning (TLS)
(B umana e al., 2014; Gua nie i e al., 2013) o S uc u e om Mo ion
and Mul i iew S e eo (S M-MVS) pho og amme y (O iz-Sanz
e al., 2013; San aga i e al., 2013). These echnologies allow o he
gene a ion o a high- esolu ion, 3D pho o ealis ic depic ion o a
Recei ed: 28 Oc obe 2022 Re ised: 10 Ap il 2023 Accep ed: 22 Ap il 2023
DOI: 10.1002/a p.1901
This is an open access a icle unde he e ms o he C ea i e Commons A ibu ion-NonComme cial-NoDe i s License, which pe mi s use and dis ibu ion in any
medium, p o ided he o iginal wo k is p ope ly ci ed, he use is non-comme cial and no modi ica ions o adap a ions a e made.
© 2023 The Au ho s. A chaeological P ospec ion published by John Wiley & Sons L d.
A chaeological P ospec ion. 2023;1–16. wileyonlinelib a y.com/jou nal/a p 1
loca ion o ea u e and p o ide mo e comple e and igo ous geome ic
documen a ion o he i age emains han can o he wise be ob ained
by adi ional echniques. Addi ionally, hese me hods a ou g ea e
objec i i y in he scien i ic- echnical s udy and a e a mo e a ac i e
o m o dissemina ing cul u al he i age o he gene al public while also
p o iding o mo e agile and e icien su eying (Aica di e al., 2018;
Dong e al., 2020). Al hough bo h TLS and S M-MVS pho og amme y
a e he p ima y echniques used o 3D he i age egis a ion, S M-
MVS has become mo e commonly used han TLS due o i s low cos
and easibili y and shows g ea po en ial in a a ie y o asks ela ed
o he geome ic egis a ion o cul u al he i age si es (Peña-Villasenín
e al., 2017,2020). Pho og amme y has a long his o y and has unde -
gone impo an ad ancemen s wi h he in oduc ion o S M-MVS
app oaches (Remondino & El-Hakim, 2006; Sna ely e al., 2006;
Wes oby e al., 2012). These me hodologies a e e en mo e ele an in
s udies o ock a due o hei nonin asi e na u e and he possibili y
o applying 3D ende ing pos ea men s, which allow documen ing
hese he i age elemen s in an objec i e way (Gil-Docampo
e al., 2019; Peña-Villasenín e al., 2019; San os-Es e ez e al., 2020).
1.1 |S M-MVS pho og amme y
The S M-MVS p ocess is di ided in o h ee main phases. Fi s , an
in e nal and ex e nal o ien a ion o he images is pe o med. Du ing
his s ep, came a posi ion and scene geome y a e econs uc ed
simul aneously h ough he au oma ic iden i ica ion o ma ching ea-
u es by he scale in a ian ea u e ans o m (SIFT) me hod
(Chand an e al., 1997; Lowe, 1999; Lowe, 2004). These ea u es
enable ini ial es ima ions o came a posi ions and objec coo dina es,
which a e hen i e a i ely e ined using nonlinea leas -squa es mini-
miza ion. The spa se bundle-adjus men sys em ‘Bundle ’(Sna ely
e al., 2008) is used o his ask. Second, an enhanced-densi y poin
cloud and a 3D mesh can be de i ed using he clus e ing iew o mul-
i iew s e eo (CMVS) algo i hm and he pa ch-based mul i iew s e eo
(PMVS2) algo i hm (Fu ukawa e al., 2010; Fu ukawa & Ponce, 2010).
Once he densi ied poin cloud is ob ained, i can be used o gene a e
3D models, digi al ele a ion models (DEMs), nadi al and side iew
o homosaics and planime ic ec o iza ions o he s udy elemen s.
Rega ding pho og aphic cap u e, nume ous s udies and documen a-
ion om pho og amme ic so wa e de elope s p o ide s anda dized
guidance on he spa ial dis ibu ions o pho og aphic cap u e o
S M-MVS pho og amme y (Agüe a-Vega e al., 2017; Ma ínez
e al., 2013; Pepe & Cos an ino, 2020; Remondino e al., 2011;
Remondino & El-Hakim, 2006).
1.2 |Documen ing aqua ic cul u al he i age wi h
UAVs and S M-MVS
I is o en di icul o access he i age si es in coas al o shallow aqua ic
en i onmen s. Pho og amme y has shown g ea po en ial o egis-
e ing a a ie y o cul u al he i age elemen s. Howe e , in inaccessible
coas al o shallow aqua ic en i onmen s, i s applica ion is di icul , and
he a chaeological p ospec ion and geome ic and opog aphic egis-
a ion may be complica ed by issues o accessibili y. The e o e, geo-
me ic image egis a ion is no always possible despi e access o
e es ial o aqua ic equipmen , which esul s in an incomple e s udy.
Simul aneous wi h he e olu ion o pho og amme y, he e was
an expansion in he ci il applica ions o unmanned ae ial ehicles
(UAVs). I s abili y o ca y a wide a ie y o senso s allows mul iple
applica ions, such as acqui ing images a low al i udes o 3D model-
ling o he i age si es o ob aining a geome ic o opog aphic e ain
eco d (Heincke e al., 2019; Themis ocleous, 2020). The ease o use
and quali y o he esul s ob ained cu en ly make UAVs a common
ool in cul u al he i age esea ch. S M-MVS pho og amme y and
UAVs gene a e a ange o possibili ies ha , in many cases, emain o
be explo ed. UAVs can be used o aking pho og aphs in inaccessible
a eas o o ae ial p ospec ion o e la ge e ains. The combina ion o
S M-MVS pho og amme y and UAVs can educe he p oblems asso-
cia ed wi h p ospec ing and egis e ing cul u al ea u es a chi ed in
inaccessible coas al o shallow aqua ic en i onmen s.
The de elopmen and op imiza ion o wo k p o ocols wi h S M-
MVS pho og amme y can ha e a conside able social and scien i ic
impac because hese echniques imp o e he quan i y and quali y o
he i age eco ds in inaccessible a eas. The main objec i e o his s udy
is o show how he in eg a ion o UAVs and S M-MVS pho og amme-
y is capable o p ospec ing and geome ically documen ing a ious
examples o his o ic, e hnog aphic and ock a si es loca ed in places
ha a e di icul o access, such as shallow aqua ic en i onmen s,
in e idal zones o coas al a eas. The case s udies in ol e h ee a eas
o in e es : (1) he emains o sal la s and associa ed ide mills;
(2) he a chaeological emains o a Roman b idge wi h e idence o
ishe y ac i i ies and wei s; and (3) coas al ock a .
2|MATERIALS AND METHODS
This sec ion desc ibes he case s udies and he main me hodologies
and equipmen used o he ield su ey, p ocessing wo k, and he
expo ing and publishing o he esul s.
2.1 |S udy cases
All case s udies a e loca ed in he no hwes e n Ibe ian Peninsula
(Figu e 1). The chosen loca ions encompass se e al common he i age
ypologies loca ed in coas al, in e idal o shallow aqua ic en i onmen s.
The main cha ac e is ics o he h ee case s udies a e p esen ed below.
2.1.1 | Case 1. Tide mill and Ull
o saline, Vilaboa,
Spain
Case 1 (Figu e 2a) was a sal mining a ea wi h a ide mill and a long
his o y o occupa ion. I is loca ed in he inne mos a ea o he Vigo
2GIL-DOCAMPO ET AL.
10990763, 0, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/a p.1901 by Uni e sidade de San iago de Compos ela, Wiley Online Lib a y on [20/06/2023]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License
Ría (a ype o io d) in Pon e ed a, Spain. Loca ed in he in e idal
zone o he Ull
o ma shes, a loca ion a ou able o his ype o s uc-
u e, he emains o a ide mill a e p ese ed, as well as he cu en ly
named Ull
o saline. The sal la s we e buil in 1637 du ing he eign
o Felipe IV (Méndez e al., 2000) and we e abandoned in he 18 h
cen u y when some o hem we e con e ed o ag a ian p oduc ion.
Remains o his complex, including a dike wi h a no h–sou h o ien a-
ion ha isola es he sal la s om he sea (Calo-Lou ido, 1997), a e
s ill p esen on he landscape. The ide mill was buil in he 19 h cen-
u y o ake ad an age o he idal o ces caused by he sal dam.
Cu en ly, only he ounda ions o he dike on which he complex
was buil emain, bu hese es iges a e impo an due o he ew
a ailable examples o hese ea u es. The cul u al complex, oge he
wi h he ma sh, which is a na u al habi a o bi ds, cons i u es a
egion o incalculable ecological and cul u al alue. The a ea was
eco e ed as a walking a ea in 2006. The wo ks a e included in he
‘Salinas do Ull
o’p ojec , which p omo es coope a ion o he ans e
o scien i ic knowledge ega ding cul u al landscapes. The in en is o
enhance he alue o he Vilaboa Sal landscapes as a he i age asse ,
al hough he p ojec i sel was concei ed as a way o le e age cul-
u al esou ces o p omo e sus ainable and quali y ou ism. Fu he -
mo e, he p ojec is in ended o ein o ce he ma i ime iden i y and
social cohesion o he coas al communi ies. Among he mos impo -
an ac ions aken o p ese e he alue o his he i age si e is o
de elop a g aphic and geome ic eco d o he ea u e and moni o
i s conse a ion s a us. Fo his pu pose, UAVs conduc ed su eys o
he in e idal zone and he sal la s, and a gene al 3D eco d o he
ide mill was de eloped.
2.1.2 | Case 2. Po oma ín Fishe ies, Po oma ín,
Spain
Fishe ies may be small dikes o dams buil ac oss he cou se o a
i e . They may be V- o W-shaped and a e posi ioned whe e
people ish o channel wa e o ish. Fishe ies a e a adi ional
hyd aulic cons uc ion, a e some imes complex wi h wei s, and a e
gene ally loca ed in a shallow place o a ocky ou c op whe e i is
possible o ish o lamp ey, salmon and o he ish species. Minho
ishe ies we e documen ed in he 12 h cen u y, bu some o hem
p obably da e back o Roman imes (Suá ez, 2017). They a e ound
in all Galician i e s, especially he Minho Ri e , and ha e mul iple
a chi ec u al a ian s. In 1908, he e we e app oxima ely 700 o
hese ishe ies h oughou only 25 km o he Low Minho Ri e basin
(Cas o Fe nández & L
opez Facal, 2019; Domínguez, 2011;
Suá ez, 2017).
The a chi ec u al de ails o his ype o cons uc ion a e an essen-
ial elemen o he his o y o his i e . An e hnog aphic s udy was
ca ied ou o documen hese ea u es, which included a high-
esolu ion geome ic egis a ion o 3.2 km o he Minho Ri e nea
he old own o Po oma ín, which was looded a e he cons uc ion
o he Belesa Rese oi in 1963 (Figu e 2b). In addi ion o mul iple
ishe ies in he a ea, he e a e di e en hyd aulic cons uc ions (a mill
and powe plan ) and he emains o an ancien Roman b idge (Ga cía
e al., 2013; Suá ez, 2017). In his case, UAV su eys o he cou se o
he i e will be pe o med du ing he ime o he lowes low o
eco d he la ges possible a ea. This is in addi ion o ob aining 3D
eco ds and de ailed plans o he s a e o conse a ion o he exis ing
he i age s uc u es along a 3.2-km s e ch ha con ains ishe ies,
wei s o a chaeological emains.
2.1.3 | Case 3. Fo nelos eng a ing. Viana do
Cas elo, Po ugal
Case 3 was a ock a eng a ing loca ed in he pa ish o Ca eço,
Viana do Cas elo, Po ugal, in an a ea along he A lan ic coas line.
The eng a ing was ound on he pocke beach o Fo nelos, on a
coas al cli ha is di icul o access (Figu e 2c). The i s ‘ske ch’o
he ca ings was pe o med by Lanhas (1969), bu he i s acing
FIGURE 1 (a) Ibe ian Peninsula. (b) Galicia and NW Po ugal. [Colou igu e can be iewed a wileyonlinelib a y.com]
GIL-DOCAMPO ET AL.3
10990763, 0, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/a p.1901 by Uni e sidade de San iago de Compos ela, Wiley Online Lib a y on [20/06/2023]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License
o he ca ings was no made un il he 1980s, which we e consid-
e ed o ha e an a ini y wi h he schema ic and semi-na u alis ic
pain ings (Bap is a, 1986; Bap is a & Magalh˜aes, 1985); in e p e a-
ions we e also made by B adley and Fáb egas-Valca ce (1998) and
B adley and Valca ce (1999). New eco ds we e subsequen ly made
(Be encou , Abad-Vidal, & Rod igues, 2017; Be encou , Sil a,
e al., 2017), which di ided he mo i s in o h ee di e en panels.
These panels desc ibed a ious equines, ho semen, a dog and an
an h opomo ph. Conside ing hese mo i s and he in e ac ion
be ween he eng a ing and he ea u es o he ou c op, i is likely
ha he images ell a eal o my hical na a i e. P e ious esea che s
also de ended he in e p e a ion ha he space chosen o he ca -
ing o hese images, he o ien a ion o he mo i s, he opog aphy o
he ou c op and i s colou a ion c ea e an imp essi e scenic e ec
o he audience (Be encou , San os Es e ez, e al., 2017;
Be encou , Sil a, e al., 2017). Based on his new in e p e a ion,
and because he eng a ings a e inc easingly e oded by wind and
wa e ac ion and a e in dange o disappea ing, i became necessa y
o conduc a 3D su ey wi h UAVs and S M-MVS pho og amme y
o he en i e sou h ace o he ou c op o be e unde s and he
ela ionship be ween he mo i s and hei physical cha ac e is ics.
The place was classi ied as P ope y o Public In e es in he O icial
Gaze e o Po ugal by Dec ee No. 26-A/92, DR, 1s se ies-B,
No. 126 on 1 June 1992, and cu en ly, he loca ion is pa o a hik-
ing ou e, PR7, and is he esponsibili y o he Municipali y o Viana
do Cas elo.
FIGURE 2 (a) Case 1. Ull
o saline. (b) Case
2. Po oma ín ishe ies. (c) Case 3. Fo nelos
eng a ing. [Colou igu e can be iewed a
wileyonlinelib a y.com]
4GIL-DOCAMPO ET AL.
10990763, 0, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/a p.1901 by Uni e sidade de San iago de Compos ela, Wiley Online Lib a y on [20/06/2023]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License
2.2 |Field wo k
The s anda d ield wo k o 3D modelling o he i age elemen s using
bo h ae ial and e es ial pho og amme y consis s o wo basic asks.
Fi s , an o ien a ion and/o scaling sys em is es ablished; and second,
he pho og aphy is planned and execu ed. In ega d o se ing up a
scaling sys em, he e a e wo main me hods. Scaling o he scene can
be accomplished h ough e e ence measu emen s o by es ablishing
a ne wo k o g ound con ol poin s (GCPs) wi h known coo dina es,
which also allows he model o be o ien ed along he XYZ axes. In he
case o scaling by e e ence, his o ien a ion mus also be done om a
e e ence such as a plumb line o le el o he Z axis o be p ope ly
o ien ed, and a compass is needed o o ien he XY axes (O iz-Sanz
e al., 2010). In inaccessible coas al o i e a eas, i is no always pos-
sible o es ablish hese necessa y e e ences, which en ails one o he
main di icul ies in he geome ic egis a ion o cul u al he i age
loca ed in his ype o a ea.
In all cases, a DJI Phan om IV eal- ime kinema ic (RTK) UAV wi h
a maximum ake-o mass (MTOM) o 1.39 kg, a 20-Mpx RGB senso
and a p ecise posi ioning module, which ensu es cen ime ic accu acy
in image posi ioning, we e used. Fo ligh planning, he GS RTK so -
wa e ha DJI p o ides wi h he Phan om IV RTK has been used. The
ecommended longi udinal and e ical o e laps o 80% and 70%,
espec i ely, we e applied. Fo he measu emen o he GCPs, a
S onex S900T GPS RTK was used. Some o he measu ed poin s we e
used as check poin s (CPs) o independen geome ic con ol
(Table 1). Al hough he echniques and equipmen used a e common
in all he s udy cases, some pa icula s a e p esen ed below.
2.2.1 | Field wo k in Case 1
This s udy a ea co e s an a ea o 28 ha. Fo he ca og aphic and
opog aphic su ey, a s anda d pho og amme ic ligh was ca ied
ou a a heigh o 100 m, which ensu es a g ound sampling dis ance
(GSD) o 2.75 cm. Figu e 3a,b shows pho os om hese ligh s. On
he o he hand, o he su ey o linea cul u al ea u es, such as he
walls o he ide mill dam, oblique ligh s we e made along bo h sides
TABLE 1 Field equipmen cos s.
Field equipmen Cos ($) Case
Phan om 4 RTK 5000 All cases
S onex GPS S900T 5000 Cases 1 and 2
S onex TS R2 W PLUS 3500 Case 2
FIGURE 3 (a) Saline nadi al pho o. (b) Tide mill nadi al pho o. (c) Tide mill oblique pho o. [Colou igu e can be iewed a wileyonlinelib a y.
com]
GIL-DOCAMPO ET AL.5
10990763, 0, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/a p.1901 by Uni e sidade de San iago de Compos ela, Wiley Online Lib a y on [20/06/2023]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License
o he elemen o model in de ail he e ical walls and cons uc ion
elemen s. Fo his, he came a was con igu ed in au oma ic shoo ing
mode e e y 3 s wi h manual pilo ing and main ained a cons an speed
o be ween 2 and 3 m/s, hus ob aining su icien o e lap. In
Figu e 3c, an example o an oblique image is shown. Rega ding he
measu emen o GCPs, no e ha bo h he sides o he s udy a ea and
he sal mine dam a e easily accessible on oo , so i was possible o
es ablish a ne wo k o GCPs wi h su icien co e age.
2.2.2 | Field wo k in Case 2
The s udy occupies an a ea o 170 ha. As in he p e ious case, a
s anda d pho og amme ic ligh a a heigh o 120 m, which ensu es
a GSD o 3.3 cm, was ca ied ou o ca og aphic and opog aphic
su eys (Figu e 4a). Fo he su ey o linea cul u al ea u es, as in
he p e ious case, manual oblique ligh s we e conduc ed wi h an
imaging in e al o 3 s. Because o he ampli ude o he s udy a ea
and he la ge numbe o su ey elemen s ha we e o en no acces-
sible, i was necessa y o ca y ou ligh s beyond isual line o sigh
(BVLOS). Fi s , o loca e he buildings (Figu e 4d), and second, o
ob ain enough images o allow a de ailed geome ic eco d o speci ic
buildings such as ishe ies o mills (Figu e 4b,c,e). To do his, se e al
passes we e planned a di e en heigh s a ound he elemen s o
in e es . In his case, i was di icul o es ablish he GCP ne wo k
due o he p esence o la ge, inaccessible a eas. To ein o ce he
geo e e encing o he cons uc ion elemen s, a S onex R2W Plus
o al s a ion (TS) was used o collec lase measu emen s, which
FIGURE 4 (a) Nadi al pho o. (b–e)
Oblique pho os. [Colou igu e can be
iewed a wileyonlinelib a y.com]
6GIL-DOCAMPO ET AL.
10990763, 0, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/a p.1901 by Uni e sidade de San iago de Compos ela, Wiley Online Lib a y on [20/06/2023]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License
made i possible o measu e he coo dina es o a ious poin s along
hese inaccessible ea u es. The es o he GCPs we e measu ed
wi h he S onex S900T GPS.
2.2.3 | Field wo k in Case 3
The hi d case s udy ela es o he use o a UAV o pho og aph a
eco ded ou c op o elabo a e i s pho og amme y. Figu e 5a shows a
gene al pho o o he ou c op, and Figu e 5b shows a de ailed pho o
o he eng a ed panels. The ligh was ca ied ou in manual mode
wi hou planning o au onomous ligh , and a pho og aphic a ange-
men was applied ha was simila o hose used wi h e es ial cam-
e as o en used in his ype o wo k (Gil-Docampo e al., 2019).
2.3 |P ocessing, expo and publica ion
Fo 3D model p ocessing, Agiso Me ashape (Agiso LLC, Russia)
pho og amme ic so wa e was used, whe eas he enhancemen and
ende ing o he eng a ing we e made possible wi h MeshLab (Visual
Compu ing Lab, ISTI - CNR, Pisa, I aly). In all cases, he h ee main
s eps o he S M-MVS p ocess we e ca ied ou . Fi s , he in e nal and
ex e nal o ien a ions o he images we e de e mined. Second, an
enhanced-densi y poin cloud was ob ained. Bo h p ocessing phases
we e ca ied ou a high quali y so ha he so wa e could use he
o iginal image esolu ion o he p ocess. This echnique gua an ees
he bes p ecision o he pho og amme ic adjus men o he came as
and he econs uc ion o he poin cloud. In bo h cases, he zeni hal
and oblique images we e p ocessed in indi idual chunks. Then, 3D
models, DEMs, nadi al and side- iew o homosaics, and planime ic
ec o iza ions we e me ged.
The la es e sions o Agiso Me ashape inco po a e a new
mesh gene a ion mode based on dep h maps ins ead o p ocessing
om he poin cloud (Ve hoe en e al., 2021). This mode was used
FIGURE 5 (a) Gene al pho o o he ou c op.
(b) De ailed pho o o he eng a ed panels. [Colou
igu e can be iewed a wileyonlinelib a y.com]
TABLE 2 P ocessing cos s.
So wa e Cos ($)
Agiso Me ashape 4000
MeshLab F ee
Wo ks a ion In el(R) Co e (TM) i9-9960X CPU @
3.10 GHz NVIDIA GeFo ce RTX 2080 Ti
4000
GIL-DOCAMPO ET AL.7
10990763, 0, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/a p.1901 by Uni e sidade de San iago de Compos ela, Wiley Online Lib a y on [20/06/2023]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License
FIGURE 6 Case 1 (a) Loca ion o he pho og aphic sho s. (b) Loca ion o g ound con ol poin s (GCPs). [Colou igu e can be iewed a
wileyonlinelib a y.com]
FIGURE 7 O hopho o o he sal
wa e inle and ou le a ea. [Colou igu e
can be iewed a wileyonlinelib a y.com]
8GIL-DOCAMPO ET AL.
10990763, 0, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/a p.1901 by Uni e sidade de San iago de Compos ela, Wiley Online Lib a y on [20/06/2023]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License
o p ocess oblique images and minimize he noise in a eas wi h
wa e . The same app oach was used in Case 3, which consis s only
o oblique pho os, o ob ain a be e de ini ion om he eng a ing.
Table 2shows he cos o he so wa e and ha dwa e used o p o-
cess he h ee cases.
To publish he esul s on he Ske chFab pla o m (which ac ually
limi s model uploads o 100 MB wi h he ee subsc ip ion), he size
o he mesh mus be educed. Subsequen ly, and in all cases, he mesh
was expo ed in Wa e on (obj) o ma , and he ex u e ile was
expo ed in JPG o ma and uploaded o he online pla o m in
comp essed ZIP o ma . On he Ske chFab pla o m, an enhancemen
ende was con igu ed o imp o e he isualiza ion o he esul s.
3|RESULTS
The esul s gene a ed in he h ee case s udies a e shown below.
3.1 |Case 1. Tide mill and Ull
o saline.
In Case 1, a o al o 3440 images we e ob ained, including 846 nadi al
and 2594 oblique pho os. In his case, 76 poin s we e measu ed, o
which 67 we e used as GCPs and 9 as CPs. The wo k las ed 8 h and
was conduc ed by wo people. Figu e 6shows he loca ion o he
pho og aphic sho s (Figu e 6a) and he GCPs (Figu e 6b).
FIGURE 8 Con ou s (20 cm) in a eas
wi h he p esence o wa e on
o hopho os and digi al ele a ion models
(DEMs). (a) A ea wi h good esul s.
(b) A ea wi h ec i iable e o s. (c) A ea
wi h in alid esul s. [Colou igu e can be
iewed a wileyonlinelib a y.com]
GIL-DOCAMPO ET AL.9
10990763, 0, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/a p.1901 by Uni e sidade de San iago de Compos ela, Wiley Online Lib a y on [20/06/2023]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License
pho og amme y. In e na ional Jou nal o A chi ec u al He i age,7,54–
67. h ps://doi.o g/10.1080/15583058.2011.606595
Heincke, B., Jackisch, R., Saa enoja, A., Salmi inne, H., Rapp, S.,
Zimme mann, R., Pi ijä i, M., Ves Sö ensen, E., Gloaguen, R., Ek, L.,
Be gs öm, J., Ka inen, A., Salehi, S., Mad iz, Y., & Middle on, M.
(2019). De eloping mul i-senso d ones o geological mapping and
mine al explo a ion: Se up and i s esul s om he MULSEDRO p o-
jec . Geological Su ey o Denma k and G eenland Bulle in,43,
e2019430302. h ps://doi.o g/10.34194/GEUSB-201943-03-02
Lanhas, F. (1969). As g a u as upes es de Mon edo . Re is a de E nog a-
ia,13(2), 367–386.
Lowe, D. G. (1999). Objec ecogni ion om local scale-in a ian ea u es.
Icc ,99(2), 1150–1157.
Lowe, G. (2004). SIFT - The scale in a ian ea u e ans o m. In e na ional
Jou nal,2,91–110.
Ma ínez, S., O iz, J., Gil, M. L., & Rego, M. T. (2013). Reco ding complex
s uc u es using close ange pho og amme y: The ca hed al o San i-
ago de Compos ela. The Pho og amme ic Reco d,28(144), 375–395.
h ps://doi.o g/10.1111/pho .12040
Méndez, G., Rey, D., Be nabeu, A. M., Manso, F., & Vilas, F. (2000). Recu -
sos mine ales ma inos en las ías gallegas y en la pla a o ma con inen-
al adyacen e. Jou nal o Ibe ian Geology,26,67–97.
O iz-Sanz, J., Gil-Docampo, M. L., Ma ínez-Rod íguez, S., Rego-
Sanma ín, M. T., & Meijide-Cameselle, G. (2013). Th ee-dimensional
modelling o a chaeological si es using close- ange au oma ic co ela-
ion pho og amme y and low-al i ude image y. A chaeological P ospec-
ion,20(3), 205–217. h ps://doi.o g/10.1002/a p.1457
O iz-Sanz, J., Gil-Docampo, M. L., Ma ínez-Rod íguez, S., Sanma ín-
Rego, M. T., & Meijide-Cameselle, G. (2010). A simple me hodology o
eco ding pe oglyphs using low-cos digi al image co ela ion pho o-
g amme y and consume -g ade digi al came as. Jou nal o A chaeologi-
cal Science,37(12), 3158–3169. h ps://doi.o g/10.1016/j.jas.2010.
07.017
Peña-Villasenín, S., Gil-Docampo, M., & O iz-Sanz, J. (2017). 3-D model-
ling o his o ic acades using SFM pho og amme y me ic documen a-
ion o di e en building ypes o a his o ic cen e. In e na ional
Jou nal o A chi ec u al He i age,11(2017), 871–890. h ps://doi.o g/
10.1080/15583058.2017.1317884
Peña-Villasenín, S., Gil-Docampo, M., & O iz-Sanz, J. (2019). P o essional
S M and TLS s a simple S M pho og amme y o 3D modelling o
ock a and adiance scaling shading in eng a ing de ec ion. Jou nal o
Cul u al He i age,37, 238–246.
Peña-Villasenín, S., Gil-Docampo, M., & O iz-Sanz, J. (2020). Desk op s
cloud compu ing so wa e o 3D measu emen o building açades:
The monas e y o San Ma ín Pina io. Measu emen ,149, 106984.
h ps://doi.o g/10.1016/j.measu emen .2019.106984
Pepe, M., & Cos an ino, D. (2020). Techniques, ools, pla o ms and algo-
i hms in close ange pho og amme y in building 3D model and 2D
ep esen a ion o objec s and complex a chi ec u es. Compu e -Aided
Design and Applica ions,18,42–65.
Remondino, F., Ba azze i, L., Nex, F., Scaioni, M., & Sa azzi, D. (2011).
UAV pho og amme y o mapping and 3d modeling–Cu en s a us
and u u e pe spec i es. The In e na ional A chi es o he Pho og amme-
y, Remo e Sensing and Spa ial In o ma ion Sciences,38(1), C22.
Remondino, F., & El-Hakim, S. (2006). Image-based 3D modelling: A
e iew. The Pho og amme ic Reco d,21(115), 269–291. h ps://doi.
o g/10.1111/j.1477-9730.2006.00383.x
San aga i, C., Inze illo, L., & Di Paola, F. (2013). Image-based modeling
echniques o a chi ec u al he i age 3D digi aliza ion: Limi s and
po en iali ies. ISPRS - In e na ional A chi es o he Pho og amme y,
Remo e Sensing and Spa ial In o ma ion Sciences, XL-5/W2
(Sep embe ), 555–560. h ps://doi.o g/10.5194/isp sa chi es-XL-5-
W2-555-2013
San os-Es e ez, M., Teje izo-Ga cía, C., & Toucido, F. A. (2020). El ab igo
con pin u a esquemá ica de Pala de Cab as (Ou ense). Encuen os y
desencuen os en e dos adiciones. Complu um,31(1), 7–24.
Sna ely, N., Sei z, S., & Szeliski, R. (2006). Pho o ou ism: Explo ing pho o
collec ions in 3D. SIGGRAPH Con e ence P oceedings, 835--846.
h ps://doi.o g/10.1145/1141911.1141964
Sna ely, N., Sei z, S. M., & Szeliski, R. (2008). Modeling he wo ld om
in e ne pho o collec ions. In e na ional Jou nal o Compu e Vision,
80(2), 189–210. h ps://doi.o g/10.1007/s11263-007-0107-3
Suá ez, M. C. (2017). Cons uci
ons popula es das se as ou ensás. Rai-
game: Re is a de A e, Cul u a e T adici
ons Popula es,41,86–101.
Themis ocleous, K. (2020). The use o UAVs o cul u al he i age and
a chaeology. In Remo e sensing o a chaeology and cul u al landscapes
(pp. 241–269). Sp inge .
Ve hoe en, G., San ne , M., & T inks, I. (2021). F om 2D ( o 3D) o 2.5 D:
No all g idded digi al su aces a e c ea ed equally. In 28 h CIPA Sym-
posium “G ea Lea ning & Digi al Emo ion”(Vol. 8, pp. 171-178).
h ps://doi.o g/10.5194/isp s-annals-VIII-M-1-2021-171-2021
Wes oby, M. J., B asing on, J., Glasse , N. F., Hamb ey, M. J., &
Reynolds, J. M. (2012). S uc u e- om-mo ion pho og amme y: A
low-cos , e ec i e ool o geoscience applica ions. Geomo phology,
179, 300–314. h ps://doi.o g/10.1016/j.geomo ph.2012.08.021
How o ci e his a icle: Gil-Docampo, M., Peña-Villasenín, S.,
Be encou , A. M. S., O iz-Sanz, J., & Pe aleda-Vázquez, S.
(2023). 3D geome ic su ey o cul u al he i age by UAV in
inaccessible coas al o shallow aqua ic en i onmen s.
A chaeological P ospec ion,1–16. h ps://doi.o g/10.1002/a p.
1901
16 GIL-DOCAMPO ET AL.
10990763, 0, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/a p.1901 by Uni e sidade de San iago de Compos ela, Wiley Online Lib a y on [20/06/2023]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License
