Figure 1. 3D Ortho vs 2D Or LoD1 city models are being regularly produc
ICGC as a by-product of the 1:1 000 top LoD2 city models from LiDAR point cloud
as intermediate information when develop efficiency applications such as photovoltaic s
Figure 2. Point cloud. LoD2 buildings. photovoltaic suitability
The ICGC acquired the oblique camera syste objective of adding a new urban sensor to
enables not only the creation of photorealist multi-view pixel-based algorithms, but also
current product portfolio. In such evolutio aims at increasing the productivity of the ob
by maximizing the number of application captured information, including 3D meshe
façade textures, NDVI orthoimagery and ste capture at 1:1000 scale.
Establishing robust production pipelines rel camera system requires an in-depth stud
capabilities. Therefore, this paper presents analysis of the oblique system based on med
cameras. The analysis focuses on differe system. On the one hand, the study
radiometric suitability of the RDC30 camera applications and stereo plotting at urban s
hand, the study of the automated aerial tria and oblique blocks which is challenged
images involved in the high-overlap flight su resolution variations along the oblique
performance of dense point matching ac viewing directions.
Figure 3. High overlap data capture configuration
Ortho. duced in urban areas at
topographic database. uds are also generated
oping specific energy ic suitability.
s. LoD2 building + stem in 2014 with the
to its portfolio, which listic 3D meshes using
so the evolution of the tion, ICGC’s analysis
oblique flight surveys ons derived from the
shes, point cloud and stereo-models for data
relying on the oblique tudy of the sensor’s
ts the current ICGC’s edium-format RCD30
ferent aspects of the y of geometric and
era for remote sensing scales; on the other
triangulation of Nadir d by the number of
surveys, the scale and ue images and the
across the different
re in maltese-cross
2. RCD30 OBLIQUE
From the whole set of models pres finally decided to acquire in 2014,
by Leica: a 60Mpixel multispec which consists of one Nadir and fo
towards the four cardinal points a The system can easily be upgrad
multi-directional motion compen deliver high quality images.
Three different block configuratio carry out the camera assessment:
T1:
Geometric study has been perf images collected with the RCD30
flying altitude AGL with 80 s block was flown in northeast – so
and a resulting GSD of 8 cm. Ab were taken from each camera.
T2:
For the radiometric assessmen the AISA Eagle II hyperspectra
configuration chosen, with a flyin knot of speed, produced 126-band
a resulting GSD of 1m. At the same was collected with the RCD30 Ob
endlap and 17 cm GSD. T3:
A block of 240 images collecte with 60 sidelap and enlap was a
evaluation. The resolution pattern of the image. The resulting GSD f
cm. For the acquisition process, the RCD
on a PAV gyro-stabilized suspe conditions during the flight tests we
3. AERIAL TRIAN
A sub-block of 866 images extract has been triangulated using the Tr
package Match-AT. Approximat were taken from each camera. For
of 16 control and check poin distributed over the block.
The simultaneous image capture w image overlap resulted in a ve
connections causing long processin Although the setting parameters o
highly restrictive to reduce the am much as possible, an average of
correlated including points connec process took 31 hours on a 64-
threads, local image storage. After distribution to approximately 100
adjustment took less than 10 minut The following input data was intr
approximately 87000 image point standard deviation
σ of 2 micron
microns manual points, GNSS c centres
σ = 3 cm for X, Y and
Nadir looking camera only; σ =
σ = 15 mdeg for kappa and grou
E TEST FLIGHTS
resent in the market, the ICGC 14, the RCD30 oblique featured
ectral medium format camera d four oblique cameras viewing
at an off-Nadir angle of 35º. aded to 80 Mpixels and has a
ensation on-board system to tions have been considered to
erformed with a block of 10095 30 Oblique camera from 770 m
sidelap and 70 endlap. The south-west direction, 36 strips
About 45 shots per flight line ent, a simultaneous flight with
tral sensor was planned. The ing height of 1650 m and 120
d AISA four strips images with me time, a block of 240 images
Oblique with 60 sidelap, 40 cted from 730 m flying altitude
s acquired for spatial resolution rn was located in different parts
for this configuration was 7.5 RCD30 Oblique was mounted
spension mount. The weather were excellent.
IANGULATION
acted from the T1 configuration Trimble Inpho v7.0.2 software
ately 11 images per flight line For accuracy assessment a total
oints were available, evenly e with 5 cameras and the high
very high degree of image sing times for image matching.
s of the matching module were amount of matched points as
of 700 points per image were necting up to 112 images. The
-bit server 16GB RAM, 16 fter thinning out the dense point
00 points per image, the block utes.
introduced into the adjustment: int coordinates with an a priori
rons automatic points and 3 S coordinates of the projection
d Z, IMU angle observations =
3 mdeg for omega and phi, round coordinates of 4 control
This contribution has been peer-reviewed. doi:10.5194isprsarchives-XLI-B3-99-2016
100
points σ =
4 cm for X, Y and Z. The considered shift and drift parameters
measurements, IMU misalignment and s parameters for each camera.
Self-calibration led to significantly impr Trimble Inpho software allows applying tw
self-calibration parameters: the 12 so-called Ebner, 1976 and the 44 so-called Grün
1979. Figure 4 shows the averaged r coordinates for the Nadir image derived fro
without self-calibration. The mayor systema compensated by applying self-calibration w
The set of 12 parameters did not result in sat accuracy.
Figure 4. Calculated distortion grid for From 12 independent check points, RMS ob
of 3.2 cm in X, 4.5 cm in Y and 6.6 cm i Figure 5 shows the graphical representat
control and check point residuals.
Figure 5. Horizontal left and vertical ground control points triangles and check p
This well characterized block-configuration preferred to generate preliminary dense
subsequent
textured meshes
using Smart3DContextCapture software package A
4. RADIOMETRIC CALIBR
