INVESTIGATIONS INTO THE ACCURACY OF THE UAV SYSTEM DJI MATRICE 300
RTK WITH THE SENSORS ZENMUSE P1 AND L1 IN THE HAMBURG TEST FIELD
T. Ke s en 1 *, J. Wol 1, M. Linds aed 1
1 Ha enCi y Uni e si y Hambu g, Pho og amme y & Lase Scanning Lab, Henning-Vosche au-Pla z 1, 20457 Hambu g, Ge many -
(Thomas.Ke s en, Joshua.Wol , Ma en.Linds aed )@hcu-hambu g.de
Commission I, WG 10
KEY WORDS: accu acy, bundle block adjus men , g ound con ol poin s, e e ence da a, RTK-GNSS, es ield, UAV/UAS.
ABSTRACT:
The de elopmen o inc easingly powe ul Unmanned Ae ial Vehicles (UAV) is p og essing con inuously, so ha hese sys ems
equipped wi h high- esolu ion senso s can be used o a a ie y o di e en applica ions. Wi h he Ma ice 300 RTK, Da-Jiang
Inno a ions Science and Technology Co. L d (DJI) has launched a sys em ha can use he high- esolu ion came a Zenmuse P1 o
he lase scanne Zenmuse L1 as a eco ding senso , among o he senso s. In o de o in es iga e he geome ic quali y o hese wo
senso s, Ha enCi y Uni e si y Hambu g, in coope a ion wi h LGV Hambu g, NLWKN in No den and he Ge man A chaeological
Ins i u e in Bonn, lew o e he 3D es ield in he Inselpa k in Hambu g-Wilhelmsbu g on 5 Augus 2021 wi h he P1 came a and
he L1 lase scanne . Using he Ma ice 300 RTK as ca ie pla o m, he es ield was eco ded in a ious con igu a ions a al i udes
be ween 50 m and 90 m abo e g ound. P io o he UAV ligh campaign, 44 ma ked g ound con ol poin s (GCP) we e signalised in
he es ield, which had al eady been su eyed by LGV in 2020 using geode ic measu emen me hods o achie e a coo dina e
accu acy o ±5 mm o each GCP. The esul s o ae ial iangula ions as well as 3D poin clouds gene a ed om image da a and lase
scanning a e compa ed wi h e e ence da a in o de o demons a e he accu acy po en ial o hese measu emen sys ems in his
pape .
* Co esponding au ho
1. INTRODUCTION
Unmanned ae ial ehicles (UAVs) a e inc easingly used in
a ious disciplines o lexible su eys o small o medium-
sized su ey a eas. The use o UAV sys ems equipped wi h
Real-Time Kinema ic (RTK) GNSS inc eases he a ac i eness
o hese sys ems o many asks, as hey o e a posi ioning
accu acy o 2-3 cm in he na ional coo dina e sys em wi h hese
senso s (Ge ke and P zybilla, 2016; P zybilla e al., 2020;
Ke s en and Linds aed , 2022). As a consequence, a signi ican
educ ion o con ol poin s is possible, making he use o RTK-
GNSS based pla o ms mo e lexible and e icien o many
applica ions. In ecen yea s, UAV sys ems wi h RTK-GNSS
ha e inc easingly es ablished hemsel es as wo kho ses o
applica ions in UAV pho og amme y. Wi h he DJI Ma ice
300 RTK, a sys em is now a ailable ha has high posi ioning
accu acy and can be equipped wi h a high- esolu ion came a o
lase scanne , among o he senso s. This makes i possible o
eco d a wide a ie y o objec s such as u ban scenes, coas al
zones, ag icul u al a eas o o es a eas.
Resul s on he geome ic quali y o ae ial iangula ions o
di e en UAV based came a sys ems ha e al eady been
published (P zybilla e al. 2019; Ke s en e al. 2020). Ge ke and
P zybilla (2016) p esen ed i s esul s on he in luence o on-
boa d RTK-GNSS and c oss- ligh s o a UAV sys em, while
P zybilla e al. (2020) published i s esul s o RTK-based
UAV pho og amme y using ou DJI Phan om 4 RTK sys ems
lown in c oss- ligh s a di e en al i ude on he si e o he
Zolle n collie y UAV es ield in Do mund. Fu he accu acy
es s ha e been ca ied ou by Zhao e al. (2020) and Zhao
(2021). In ecen yea s, unmanned ae ial sys ems wi h RTK-
GNSS a e s a e-o - he-a in UAV pho og amme ic
applica ions.
In o de o in es iga e he geome ic accu acy po en ial o hese
wo senso s P1 and L1 on-boa d he UAV sys em Ma ice 300
RTK, Ha enCi y Uni e si y Hambu g, in coope a ion wi h he
S a e O ice o Geoin o ma ion and Su eying (LGV)
Hambu g, he Lowe Saxony S a e O ice o Wa e
Managemen , Coas al and Na u e Conse a ion (NLWKN) in
No den, Ge many and he Ge man A chaeological Ins i u e
(DAI) in Bonn, ca ied ou ae ial ligh s o e he 3D es ield in
he Inselpa k o Hambu g-Wilhelmsbu g on Augus 5 h, 2021.
The UAV ligh s we e conduc ed in a ious ligh
con igu a ions and a ligh al i udes be ween 50 m and 90 m
abo e g ound. Fo accu acy in es iga ions, he image
o ien a ions and came a calib a ions o he di e en UAV
image ligh s we e calcula ed by ae ial iangula ion using he
so wa e Agiso Me ashape. The accu acies o ae ial
iangula ion we e analysed using di e en g ound con ol and
check poin con igu a ions. The accu acy po en ial o he lase
scanne was analysed using geode ic check poin s and e e ence
da a (p o iles and selec ed a eas) o a e es ial lase scanne .
Addi ionally he lase poin clouds we e compa ed wi h image-
based poin clouds o P1 and wi h o icial da a o ai bo ne lase
scanning p o ided by LGV.
The ollowing ques ions, among o he s, a e answe ed:
 Wha accu acies (ae ial iangula ion and e ain models)
a e achie ed by he UAV ligh s o he wo eco ding
sys ems in hese in es iga ions?
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, Volume XLIII-B1-2022
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 Which ae ial ligh con igu a ions p o ide he bes esul s
compa ed o e e ence?
 Is i possible o educe he numbe o GCP wi h
co esponding lowe accu acy equi emen s o p ojec s
when using accu a e RTK-GNSS obse a ions o UAV
ligh s?
2. THE UAV TEST FIELD IN WILHELMSBURG
INSELPARK
In he Inselpa k in Hambu g's Wilhelmsbu g dis ic , which
hos ed he In e na ional Ga den Show in 2013, he LGV
Hambu g se up a es ield o UAV sys ems consis ing o 45
g ound con ol poin s (GCP) on an a ea o 150 m × 300 m. The
GCP coo dina es we e de e mined using a ious geode ic
measu emen me hods and he heigh s we e addi ionally
de e mined by le elling. The LGV speci ies a coo dina e
accu acy o ± 5 mm o each GCP coo dina e. As can be seen in
Figu e 1, he GCP a e e enly dis ibu ed o e his
app oxima ely 4.5 ha a ea o he Inselpa k. P io o he su ey
on Augus 5 h, 2021, 44 GCP we e signalised on g ass, asphal
and sand using a ge boa ds made o wa e p oo plas ic wi h
dimensions o 50 cm × 50 cm (Fig. 1, igh ).
Figu e 1: G ound con ol poin dis ibu ion in he UAV es
ield Inselpa k Hambu g-Wilhelmsbu g (le ) and a ge s on
di e en su aces ( igh ) - g ass, asphal , sand and s one.
3. THE UAV SYSTEM USED
The DJI Ma ice 300 RTK (Figu e 2) is a 6.3 kg quadcop e
om he Chinese manu ac u e DJI Technology, which can be
ope a ed a al i udes o up o 5000 m wi h a maximum ligh
ime o 55 minu es. Equipped wi h he Au oma ic Dependen
Su eillance - B oadcas (ADS-B) an i-collision sys em, he
UAV can achie e a posi ioning accu acy o 1.0-1.5 cm + 1 ppm
using RTK-GNSS. In con as o many compa able sys ems, he
M300 RTK does no ha e a ixed senso , ins ead he pla o m
can be equipped wi h a ious senso s such as he came a DJI
Zenmuse P1 o he (ai bo ne) lase scanne DJI Zenmuse L1 o
ae ial ligh s. The M300 RTK is powe ed by wo TB60
ba e ies. Fo longe missions, he ba e ies can be eplaced one
a e he o he du ing ope a ion a e landing wi hou
disconnec ing he senso sys em om he powe supply.
3.1 The DJI Zenmuse P1 Came a
The DJI Zenmuse P1 came a (Figu e 3 le ) is o e ed by DJI
o he Ma ice 300 RTK. This is a 45 megapixel (pixel size 4.4
μm) digi al came a equipped wi h a ull- ame (35.9 mm × 24
mm) CMOS senso ha can be ope a ed wi h a ious lenses
o e ed wi h di e en ocal leng hs. In he con ex o hese
in es iga ions, a lens wi h a ocal leng h o 35 mm was used,
which has a ield o iew (FOV) o 63.5° and can ake pho os in
an ape u e ange (F-S ops) o F2.8 o F16.
Figu e 2: Top - DJI Ma ice 300 RTK wi h Zenmuse P1
came a (le ) and L1 lase scanne ( igh ), bo om - Zenmuse P1
came a (le ) and L1 lase scanne ( igh ).
3.2 The DJI Zenmuse L1 Ai bo ne Lase Scanne
In addi ion o he P1 came a, he Ma ice 300 RTK can
op ionally be used wi h he DJI Zenmuse L1 ai bo ne lase
scanning senso (Figu e 3 igh ), which is he i s lase scanne
om DJI. This scanne , which is equipped wi h a LiDAR
module om he manu ac u e Li ox, has a ange o 450 m
wi h a FOV o 70° (LIVOX 2022). In ligh planning, a choice
can be made be ween single- e u n o mul iple- e u n mode. In
addi ion, wo di e en scanning modes a e a ailable, which
esul in di e en poin pa e ns o speci ic equi emen s o
objec s o be scanned, and which enable scanning o up o
240,000 poin s pe second. Howe e , he L1 senso also
manages up o h ee e u ns pe lase sho , so ha he poin a e
can be up o 480,000 poin s pe second when scanning
ege a ion, o example, wi h wo o h ee e u ns (Singh,
2020). These wo scanning modes a e e e ed o by DJI as
epe i i e and non- epe i i e (Fig. 4). Acco ding o he
manu ac u e , he L1 senso achie es a sys em accu acy o 10
cm in a i ude and 5 cm in al i ude a a lying heigh o 50 m
abo e g ound. Un o una ely, i is no clea om he
manu ac u e 's echnical speci ica ion whe he he sys em
accu acy e e s o posi ioning o 3D poin de e mina ion. The
p ecision o he dis ance measu emen (RMS 1σ) o he lase
scanne is speci ied as 3 cm a a dis ance o 100 m (DJI 2022).
Figu e 3: Non- epe i i e ci cula scanning (le ) and epe i i e
line scanning ( igh ) wi h he L1 lase scanne (LIVOX 2022).
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, Volume XLIII-B1-2022
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3.3 Ae ial ligh con igu a ions
Fi s , he es ield was eco ded by wo image ligh s wi h he
Ma ice 300 RTK/Zenmuse P1 sys em (Table 1). These wo
ligh s ook place a an al i ude o 70 m and 90 m abo e g ound.
Du ing he i s ligh , a combina ion o nadi and oblique
images (backwa ds and sideways) was aken, while du ing he
second ligh a he highe al i ude only nadi images we e
aken. This esul ed in a G ound Sampling Dis ance (GSD) o
8.8 mm o he nadi images and 10.2 mm (image cen e) o
he oblique images (oblique) a an angle o 60° o he i s
ligh , while he second nadi ligh had a GSD o 11.3 mm. Fo
bo h ligh s, he exposu e ime was se o 1/1000 sec, while he
F-S op a ied be ween 4 and 7.1 and he ligh sensi i i y o he
senso be ween ISO 400 and 640 o an op imal exposed image.
Pa ame e Ae ial ligh 1 Ae ial ligh 2
Flying heigh 70 m 90 m
Reco ding angle Nadi and Oblique Nadi
GSD (cen e) 8.8 mm / 10.2 mm 11.3 mm
O e lapping 80 % / 80 % 80 % / 80 %
Flying ime 39 min 25 s 9 min 18 s
Pho os 2215 408
Table 1. Ae ial ligh s wi h he Zenmuse P1 came a.
Subsequen ly, h ee ligh s o e he es ield we e ca ied ou
wi h he Zenmuse L1 lase scanne (Table 2). The di e en
scanning modes we e compa ed and he in luence o inc easing
he ligh al i ude om 50 m o 90 m was in es iga ed. The s ip
o e lap was se o 60% o all ligh s. In addi ion, mul iple
e u n echo mode was used on all ligh s o in es iga e he
abili y o lase scanning o pene a e ege a ion. A e he s a
o he UAV ligh , he lase scanne and he ine ial
measu emen uni we e calib a ed in he ai by a eco ding
p ocedu e implemen ed by he manu ac u e be o e he ac ual
da a acquisi ion s a ed. Du ing he ligh and scanning
ope a ion, he 3D poin cloud was al eady colou ed in eal ime
by he RGB alues o he Zenmuse X4S came a (20
megapixels) in eg a ed in he lase scanne and displayed on he
DJI En e p ise sma emo e con ol, which has an ul a-b igh
5.5-inch 1080p display o con olling he UAV sys em du ing
ligh .
Pa ame e Fligh 3 Fligh 4 Fligh 5
Flying heigh 50 m 90 m 50 m
Poin densi y 399 p s/m² 209 p s/m² 445 p s/m²
Scanning mode epe i i e epe i i e non- epe i i .
Echo mode mul iple- e u n
O e lapping 60 % 60 % 60 %
Flying ime 13 min 4 s 8 min 19 s 13 min 4 s
Table 2. Ae ial ligh s wi h he Zenmuse L1 lase scanne .
4. DATA EVALUATION AND RESULTS
The eco ded ae ial image blocks we e e alua ed in he
so wa e Agiso Me ashape V1.7 using he signalised 44 GCP.
The ae ial iangula ions o bo h image ligh con igu a ions
we e calcula ed wi h di e en GCP con igu a ions in o de o
assess he quali y o he esul s based on di e en a ian s
simila o (Ke s en e al., 2020). In Agiso Me ashape, he
image poin measu emen s we e pe o med au oma ically and
he GCP measu emen s semi-au oma ically. In he subsequen
bundle block adjus men s, he so wa e calcula ed he image
o ien a ion and came a calib a ion pa ame e s o each GCP
e sion. In he nex s ep, 3D poin clouds we e gene a ed by
dense image ma ching o he pho o blocks o UAV ligh s 1
and 2 using he o ien a ion pa ame e s o he e sion wi h all 44
GCP.
The da a om he Zenmuse L1 lase scanne can (cu en ly)
only be analysed wi h he DJI Te a so wa e. The impo ed
poin clouds o he h ee ligh s we e each op imised by s ip
adjus men and inally expo ed in LAS o ma in he UTM
coo dina e sys em (EPSG 4647) and wi h ellipsoidal heigh s,
jus like he poin clouds gene a ed in he pho os. The highes
quali y le el was selec ed o he da a p ocessing.
The quali y o he 3D poin clouds gene a ed om he acqui ed
da a o he i e UAV ligh s was in es iga ed using 44 checks
poin s (ChP) and by compa ing di e en p o iles and e e ence
su aces acqui ed wi h a FARO Focus3D X330 e es ial lase
scanne . The e e ence da a we e scanned a ound he building,
which is isible in Figs. 8 and 10, in 29 scans ( esolu ion 1/5
and quali y 3x). When egis e ing he scans in he FARO®
SCENE so wa e, an a e age poin e o o 4.2 mm was
achie ed. Compa able geome ic accu acy in es iga ions o
image-based 3D poin clouds ha e al eady been ca ied ou o
a ious UAV sys ems in he es ield a he Zolle n collie y in
Do mund (P zybilla e al., 2019).
4.1 Compa ison o he Resul s o he Ae ial T iangula ion
Fo de ailed accu acy in es iga ions, di e en GCP e sions
wi h di e en numbe s o spa ially well dis ibu ed g ound
con ol poin s (all GCPs, 12, 5 and 1 GCP) we e calcula ed in
bundle block adjus men s, whe eby all GCP no aken in o
accoun we e hen used as check poin s. In all bundle
adjus men s, he posi ioning coo dina es o he ex e io
o ien a ion showed an RMSE (Roo Mean Squa e E o ) in he
ange o 11 o 16 mm, while he de ia ions o he heigh
coo dina es we e calcula ed a app ox. 11 mm. The a e aged
s anda d de ia ions o he RTK-GNSS measu emen s o he
image posi ions o bo h image ligh s we e 15 mm in a i ude
and 29 mm in heigh . Howe e , he indi idual alues o he
RTK-GNSS measu emen s pe image posi ion we e in oduced
in o he bundle adjus men as a p io i s anda d de ia ion.
The esul s o UAV image ligh 1 wi h nadi and oblique
images (2215 pho os) a e summa ised in Figu e 5. The GCP
ha e been measu ed on a e age in 155 pho os. The a p io i
s anda d de ia ion o each con ol poin coo dina e was se o 5
mm in each adjus men e sion. In he bundle adjus men
wi hou GCP o wi h a single con ol poin , he de ia ions a he
43 and 44 checks poin s a e o X = 15 mm and Y = 11 mm,
whe eby he de ia ions a he heigh Z a e highe by a ac o o
2.8 wi h up o 42 mm ( igh wo columns in Fig. 5). E en in he
adjus men wi h all GCP, he RMSE o he check poin s is 19
mm in he heigh coo dina e, while he XY coo dina es a e a
a e age de ia ions o 10 mm and 5 mm espec i ely. The ewe
GCP a e used in he adjus men , he signi ican ly highe he
RMSE alues in he heigh coo dina e become. Due o he e y
high edundancy caused by obse a ions in 2215 ae ial images,
a signi ican ly be e esul was expec ed, which was hen
achie ed wi h image ligh 2 (Fig. 6). Causes o he la ge
heigh de ia ions in he GCP and ChP could be he geome y o
he ligh con igu a ion, he na ow FOV o he lens as well as
he eco ding p ocedu e wi h he pi o ing o he came a on he
le e a m (gimbal) and he associa ed change in ocusing o
oblique images compa ed o nadi images, which hus also
in luences he came a calib a ion. DJI de ines he ec o o he
le e a m om he GNSS an enna cen e o he p ojec ion
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, Volume XLIII-B1-2022
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341
cen e o he came a, which should ha e only mino co ec ion
e ec s on he esul .
The ep ojec ion e o , a geome ic e o co esponding o he
dis ance in he image be ween a p ojec ed and a measu ed
image poin , was 0.4 pixels o image ligh 1 and 0.3 pixels o
image ligh 2. The image poin measu emen accu acy o he
signalised GCP was de e mined o be 0.2 pixels o bo h image
blocks.
The esul s o UAV ligh 2 including only 408 nadi images a e
summa ised in Figu e 6. Each GCP was measu ed on a e age in
23 pho os. As an a p io i s anda d de ia ion, 5 mm was chosen
o all h ee coo dina es o he GCP in he adjus men s, which
co esponds o he accu acy achie ed by he geode ic GCP
de e mina ion. This assump ion o he s anda d de ia ion was
con i med by he adjus men using all GCP (Fig. 6 le column).
E en wi h dec easing numbe o con ol poin s, he de ia ions
(RMSE) a he check poin s emain a 10 mm o be e . I can
also be seen ha using only a single GCP s abilises he esul o
he adjus men in he posi ion and heigh o he check poin s
( igh columns in Fig. 6). F om his i is concluded ha despi e
he accu a e RTK-GNSS measu emen s o he image posi ions
du ing he ae ial ligh , a leas one GCP should be placed in he
objec a ea o achie e an accep able esul o he ae ial
iangula ion, especially a al i ude. The impo ance and
in luence o g ound con ol poin s o ae ial pho o iangula ion,
especially o ae ial ligh s wi hou RTK-GNSS, is shown by
(Linds aed and Ke s en, 2018) o a ious p ojec s.
Uni
[
m
]
F1-P1 F2-P1 F3-L1 F4-L1 F5-L1
Max. de . + -0
,
019 0
,
013 0
,
039 0
,
041 0
,
035
Max. de - -0,063 -0,029 -0,032 -0,036 -0,030
A . de -0,039 -0,000 -0,000 -0,002 0,006
S d. de . 0,008 0,008 0,015 0,019 0,015
Table 3. De ia ions (Z) o 3D poin clouds a 44 check poin s
o ligh 1-5 and P1 and L1.
4.2 Poin -based compa ison
Fo poin -by-poin compa isons, he sho es dis ance (in
e ical di ec ion) be ween he check poin s (ChP) and he
dense poin cloud is calcula ed. Due o he high poin densi y
(see Tab. 4) and he la a ge signs, i is assumed ha he Z-
coo dina e a ound he cen e o he a ge sign is he same. The
dis ibu ion o GCP o he s udy a ea is shown in Fig. 1. Tab. 3
summa ises he mean, maximum (posi i e) and minimum
(nega i e) de ia ions (Z in m) in he de i ed poin clouds o he
di e en UAV ligh s o 44 check poin s. The dense poin cloud
Figu e 5. Resul s o bundle block adjus men s wi h di e en con ol and check poin e sions
o UAV ligh 1 using Zenmuse P1 came a.
Figu e 6. Resul s o bundle block adjus men s wi h di e en con ol and check poin e sions
o UAV ligh 2 using Zenmuse P1 came a.
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, Volume XLIII-B1-2022
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342
was c ea ed in Me ashape wi h he esolu ion "medium" om
he image da a o ligh s 1 and 2, while he poin clouds o
ligh s 3-5 we e acqui ed di ec ly om he lase scanne and
p ocessed in he DJI Te a so wa e.
The esul s show ha he ae ial ligh wi h he combina ion o
nadi and oblique images has a sys ema ic heigh o se o 39
mm, which also occu s in he ae ial iangula ion esul s due o
he de ia ions (RMSE) a he check poin s in he same ange.
This esul is also documen ed in Figu e 7 (le ) by he ed
colou ing o he check poin s. In con as , only small local
sys ema ic e ec s a e isible in Fig. 7 ( igh ), which, howe e ,
esul in small de ia ions a he check poin s. The smalles
de ia ions a he check poin s we e achie ed wi h he nadi
images ( ligh 2), as he maximum nega i e de ia ion anges
om -29 mm o a maximum posi i e de ia ion o 13 mm and
hus has a span o 42 mm (Tab. 3). Fo he h ee da a se s o he
lase scanne , an equal le el o accu acy is achie ed in each
da a se , which di e s only sligh ly om he good esul o
image ligh 2.
Figu e 7. Colou -coded de ia ions in al i ude a he check
poin s - ae ial ligh 1 ( op) and ligh 2 (bo om) each wi h he
Zenmuse P1 came a.
4.3 Line-based compa ison
In he line-by-line compa isons be ween p o iles om he poin
clouds o he i e UAV ligh s and e e ence da a, objec a eas
wi h heigh di e ences we e selec ed in he s udy a ea scanned
wi h he e es ial scanne (Fig. 8), such as s ai s (p o iles 1-3)
and a house açade wi h oo s uc u e (p o ile 4). The quali y
o he poin clouds was isually analysed he e using p o iles 2
(s ai s) and 4 (house wall) as examples (Fig. 9). In he isual
compa ison be ween he gene a ed p o iles and he e e ence
da a o he e es ial scanne , he measu emen noise in he
poin clouds o he L1 lase scanne can be seen on he one
hand and he qui e good ep oduc ion o he s ai s in he poin
clouds o he UAV image ligh s on he o he hand (Fig. 9 le ).
The compa ison o he esul s shows a e y simila esul o
p o iles 1 and 3 as o p o ile 2. As expec ed, he poin cloud o
image ligh 1 showed a e y good i o he house wall below
he oo o e hang due o he oblique images in p o ile 4 (Fig. 9
igh ), while he o he poin clouds a e smoo hed in he a ea o
he oo o e hang. Especially in p o ile 4, he ad an age o
oblique images can be demons a ed i e ical s uc u es in
dense poin clouds should be measu ed. Fo he compa ison o
he p o iles, ai bo ne lase scanning da a om 2020 was also
used, which was acqui ed on behal o he LGV Hambu g using
a RIEGL VQ-780II lase scanne wi h a poin spacing o
app ox. 10 cm as he esul . In his da a se , he s ai s a e also
sligh ly smoo hed, bu due o he small numbe o poin s and
p esumably good il e ing including smoo hing, measu emen
noise is no ob iously isible.
Figu e 8. Selec ed p o iles o compa ison wi h e e ence da a
o e es ial scanne .
Figu e 9. Compa ison o p o ile 2 c ea ed om di e en poin
clouds wi h e e ence da a om e es ial lase scanning.
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, Volume XLIII-B1-2022
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343

4.4 A ea-based compa isons
Fo he a eal compa isons wi h he a ailable e e ence da a, he
di e en poin clouds om he i e UAV ligh s in h ee
selec ed es a eas we e analysed. The es a eas o he a eal 3D
compa isons a e shown in Fig. 10. The selec ed a eas ep esen
su aces wi h a ying su ace s uc u es: A ea 1 (pa ing s ones,
conc e e and sand), A ea 2 (smoo h pa ing s ones) and A ea 3
(wood, sand and lawn). Fo he es a eas (a eas 1 and 2), poin
clouds om e es ial lase scanning wi h he FARO Focus3D
X330 a e a ailable as e e ence da a (Fig. 11 and 12), while o
a ea 3, compa isons we e only made be ween he poin clouds
om image ligh 2 (nadi images) as he bes da a se o he
image-based poin clouds wi h he h ee di e en poin clouds
o lase scanning (Fig. 13). In addi ion, a compa ison was also
made wi h he ai bo ne lase scanning da a om he Riegl
scanne (Fig. 14).
Figu e 10. O e iew o es a eas in he Wilhelmsbu g
Inselpa k (ou lined in ed): A ea 1 (pa ing s ones, conc e e and
sand), A ea 2 (smoo h pa ing s ones) and A ea 3 (wood, sand
and lawn).
Tables 4 and 5 summa ise he de ia ions (in Z) be ween he 3D
poin clouds o all i e ligh s and he TLS e e ence da a o
a ea 1 and 2, which we e calcula ed in CloudCompa e, as we e
he p e ious compa isons.
The ollowing esul s can be summa ized:
 Fligh 4 wi h he lase scanne L1 has he lowes numbe
o poin s pe m2 due o i s ligh al i ude o 90 m abo e
g ound and, oge he wi h ligh 5, he highes maximum
de ia ions o he la ges span as he amoun o he sum o
maximum nega i e and posi i e de ia ion.
 Fligh 2 wi h he Zenmuse P1 came a has he bes esul s
in e ms o maximum de ia ion, span, a e age de ia ion
and s anda d de ia ion. Howe e , he numbe o poin s
pe m2 o bo h a eas is lowe han o he o he ligh s,
also due o he ligh al i ude. Only ligh 4 wi h lase
scanne L1 lown a 90 m abo e g ound has a lowe
numbe o poin s pe m2.
 The di e ences be ween he wo lase scanne ligh s 3
and 5 a e e y small, so ha one can conclude om hese
esul s ha he e is no di e ence in he esul o he wo
scan modes epe i i e and non- epe i i e in he a ailable
da a se s.
 The image-based 3D poin clouds o ligh s 1 and 2
p o ide be e esul s han he poin clouds o he ligh s
wi h he lase scanne . Wi h he combina ion o nadi and
oblique images combined wi h he signi ican ly highe
numbe o pho os, he highes poin densi y pe m2 is
achie ed.
 Especially in a ea 2 wi h he smoo h pa ing s ones, he
image-based poin clouds achie e signi ican ly be e
esul s han hose o he lase scanne .
 Wi h s anda d de ia ions o 5 mm o 40 mm om he
e e ence, good esul s we e achie ed o he di e en
gene a ed poin clouds (P1 and L1) in he poin -by-poin
and a ea-by-a ea compa isons.
Tes a ea 1 F1-P1 F2-P1 F3-L1 F4-L1 F5-L1
Max. de .
+
0
.
243
0
.
208
0
.
296
0
.
500
0
.
302
Max. de . - -0.252 -0.209 -0.283 -0.255 -0.251
S
p
an 0.495 0.417 0.579 0.755 0.553
A . de 0.056 0.020 0.025 0.029 0.013
S d. de . 0.029 0.029 0.028 0.038 0.029
Poin s
/
m
2 745.5 578.4 656.4 325.8 681.2
Table 4. De ia ions (Z) o 3D poin clouds o P1 and L1 a
es a ea 1 o ligh 1-5 (Uni [m]).
Tes a ea 2 F1-P1 F2-P1 F3-L1 F4-L1 F5-L1
Max. de .
+
0
.
153
0
.
016
0
.
099
0
.
115
0
.
124
Max. de . - -0
,
047 -0
,
034 -0
,
220 -0
,
224 -0
,
244
S
p
an 0.200 0.050 0.319 0.339 0.368
A . de 0.037 0.003 -0.036 -0.022 -0.012
S d. de . 0.005 0.005 0.017 0.030 0.012
Poin s/
m
2 644.6 501.3 589.9 314.5 629.0
Table 5. De ia ions (Z) o 3D poin clouds o P1 and L1 a
es a ea 2 o ligh 1-5 (Uni [m]).
The ollowing Fig. 11-14 isualises he colou -coded de ia ions
o he 3D compa ison calcula ed in CloudCompa e be ween he
es da a se o he espec i e 3D poin cloud and he e e ence
o compa a i e da a. The colou -coded scale shows he
de ia ions in he ange o ±2.5 cm in g een, while he posi i e
maximum wi h +25 cm is shown in ed and he nega i e
minimum wi h -25 cm in blue. The colou -coded isualisa ion
o he de ia ions makes i easie o ecognise sys ema ics
e ec s in he esul .
In he le -hand g aphs o Figu es 11 and 12, sys ema ic
de ia ions (yellow colou ing) o he TLS e e ence da a can be
seen in he poin cloud gene a ed by pho os o ligh 1 o es
a ea 1 and 2. In con as , o he poin clouds o ligh 2, as
al eady isible in p o ile 2 (Fig. 9 le ), de ia ions can only be
seen a he edges o he s ai s. The de ia ions a he edges o he
s ai s a e somewha mo e p onounced in he poin cloud o
ligh 3 wi h he lase scanne (see cen e in Fig. 11 igh ). In
he su ace o he es a ea, he di e ences o he e e ence da a
a e somewha la ge , whe eby e ec s om he s ip adjus men
a e p obably also isible he e. Fig. 12 shows an example o he
measu emen noise o he senso o ligh 5 (L1) wi h a sligh
sys ema ic e ec a al i ude (yellow colou ing).
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, Volume XLIII-B1-2022
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344
Since no e e ence da a we e a ailable o es a ea 3,
compa isons we e only made be ween he poin clouds o ligh
2 (nadi images) as he bes da a se o image-based poin
clouds and he h ee di e en poin clouds om he L1 lase
scanne (Fig. 13). The colou ep esen a ion o he de ia ions
be ween he poin clouds o ligh 2 and he lase scanne poin
clouds also shows sligh sys ema ic e ec s in heigh (yellow
colou ing in Fig. 13 le , eddish colou ing in he le pa o
Fig. 13 cen e and blue colou ing in he le pa o Fig. 13
igh ). O e all, he heigh di e ences be ween he poin clouds
a e wi hin he speci ied accu acy ange o he Zenmuse L1
senso (see chap e 3.2).
Fo a isual compa ison o he UAV-based poin clouds, poin
clouds acqui ed by ai bo ne lase scanning (ALS) wi h he
RIEGL VQ-780II lase scanne could also be used. The da a
was p o ided by LGV Hambu g om an ALS su ey in Ma ch
2020. These ALS da a canno se e as a e e ence due o he
low poin densi y o 23 poin s pe m² and he p esumably
poo e heigh accu acy, bu hey e eal sys ema ic e ec s in he
UAV-based poin clouds. Fig. 14 isualises he esul s o he
3D compa isons. He e i is again clea ha he poin clouds o
ligh 1 a e sys ema ically oo high o e all, while he poin
clouds o ligh 2 and o he ligh s wi h he L1 i oge he
su p isingly well. The e, he di e ences a e, among o he
hings, due o he di e en eco ding da e, he ege a ion
g ow h and he di e en accu acy anges.
5. CONCLUSION AND OUTLOOK
This pape summa ises he i s esul s o he accu acy
in es iga ions o he UAV sys em DJI Ma ice 300 RTK wi h
he senso s Zenmuse P1 and L1 in he Hambu g es ield
Figu e 11. Compa ison o poin clouds o TLS ( e e ence) o UAV ligh s 1, 2 and 3 on es a ea 1.
Figu e 12. Compa ison o poin clouds o TLS ( e e ence) o UAV ligh s 1, 2 and 5 on es a ea 2.
Figu e 13. Compa ison o poin clouds o ligh 2 (P1) o poin clouds o ligh s 3, 4 and 5 (each L1) on es a ea 3.
Figu e 14. Compa ison o poin clouds o ai bo ne lase scanning wi h he RIEGL VQ-780II o poin clouds o UAV ligh s 1,
2 and 5 on es a ea 3.
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, Volume XLIII-B1-2022
XXIV ISPRS Cong ess (2022 edi ion), 6–11 June 2022, Nice, F ance
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345
Inselpa k. Fligh planning and con ol was e y easy using he
DJI Pilo app, which is e y use - iendly and allows au oma ed
ligh s. Compa ed o he DJI Phan om 4 P o, he ligh ime is
wice as long due o he wo ba e ies on he ai c a pla o m. A
sys em shu down is no necessa y when changing he ba e ies
because bo h ba e ies can be changed one a e he o he . Due
o he swi ched-on powe supply, he pa ame e s o he in e io
o ien a ion p esumably also emain s able o he came a.
The esul s o he ae ial iangula ions show ha o UAV
p ojec s wi h somewha lowe accu acy equi emen s o checks
poin s (XYZ = 3-5 cm), e.g. opog aphic applica ions, i is
possible o compu e he bundle block adjus men e en wi hou
GCP coo dina es, since he s anda d de ia ions o he ex e io
o ien a ion pa ame e XYZ can nowadays each 1-2 cm in XY
and 2-3 cm in heigh Z by RTK-GNSS measu emen s. Fo
easons o eliabili y, a leas one bu p e e ably i e GCP
should be used a he co ne and in he cen e o objec space.
Fo he esul s o ae ial iangula ion, an accu acy o one GSD
was expec ed, bu his was only achie ed in ae ial ligh 2 when
he pho o block was o ien ed using a leas i e GCP. The ae ial
iangula ion o he nadi images ( ligh 2) achie ed o e all
signi ican ly be e esul s a he check poin s han he ligh 1
wi h he combina ion o nadi and oblique images, whe e he
heigh componen showed de ia ions o up o 42 mm o all
bundle block adjus men s. This combina ion o image sho s
du ing he ae ial ligh (nadi -backwa d-sideways) p o ides
e y good co e age o he e ain su ace, bu he je ky
mo emen s o he came a and he ongoing e ocusing o he
lens due o he changing shoo ing pe spec i es p obably p o ide
uns able came a geome y. Howe e , his assump ion s ill has
o be e i ied wi h he help o he image da a by spli ing he
ae ial image con igu a ion o ligh 1 in o h ee blocks (nadi
images, oblique images backwa ds and oblique images
sideways) so ha h ee sepa a e came a calib a ions can be
calcula ed.
The examina ions o he 3D poin clouds showed a clea esul :
Ae ial ligh 2 wi h nadi images p oduced he bes esul s in
compa ison wi h he o he ligh s, while wi h he image da a o
ligh 1 a sys ema ic heigh shi occu ed in he check poin s, in
he p o iles and also in he a ea-by-a ea compa ison using
e e ence da a, which was no o be expec ed in his way. The
h ee poin clouds o he Zenmuse L1 lase scanne showed
e y simila esul s, which a e e en sligh ly be e han he
accu acy speci ica ions o he manu ac u e . A signi ican
di e ence in he quali y o he poin clouds could no be ound
in he wo scanning modes in he p esen s udy. In es iga ions
in o he pe o mance o he lase scanne o applica ions in he
de ec ion o ege a ion such as ees and bushes ha e no ye
been ca ied ou wi h his da a se s.
ACKNOWLEDGEMENTS
We would like o hank Dipl.-Ing. Holge Di ks (NLWKN in
No den) o p o iding he Ma ice 300 RTK wi h he Zenmuse
P1 came a and o lying o e he es ield. We would also like
o hank Dipl.-Ing. Ch is ian Ha l-Rei e (DAI in Bonn) o
p o iding he Zenmuse L1 lase scanne and o his suppo
du ing he UAV ligh s. The es si e a Inselpa k Hambu g-
Wilhelmsbu g was se up, signalised and made a ailable by he
s a o he S a e O ice o Geoin o ma ion and Su eying
Hambu g unde he di ec ion o M.Sc. Ma in Helms, o which
we would like o exp ess ou since e hanks.
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This con ibu ion has been pee - e iewed.
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