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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004
2.1 Digital 360? Panoramic Camera (M2)
The digital panoramic camera EYESCAN will be preliminary
used as a measurement system to create high-resolution 360?
panoramic images for photogrammetry and computer vision
(Scheibe, 2001, Klette, 2001). The sensor principle is based on a
CCD line, which is mounted on a turntable parallel to the
rotation direction. Moving the turntable generates the second
image direction. To reach highest resolution and a large field of
view a CCD-line with more then 10,000 pixels is used. This
CCD is a RGB triplet and allows acquiring true colour images.
A high SNR electronic design allows a short capture time for a
360? scan.
EYESCAN is designed for rugged everyday field use as well as
for the laboratory measurement. Combined with a robust and
powerful portable PC it becomes easy to capture seamless
digital panoramic pictures. The sensor system consists of the
camera head, the optical part (optics, depth dependencies) and
the high precision turntable with DC-gear-system motor.
Number of Pixel 3*10200 (RGB)
Radiometric 14 bit / 8 bit per channel
dynamic/resolution
Shutter speed 4ms up to infinite
Data rate 15 Mbytes / s
Data volume 360? (optics | 3GBytes
f-60mm)
Acquisition time 4 min
Power supply 12 V
Table 1. Technical parameter of the digital panoramic camera
Table 1 summarise the principle features of the camera: The
camera head is connected to the PC with a bidirectional fibre
link for data transmission and camera control. The camera head
is mounted on a tilt unit for vertical tilt of x30? with 15° stops.
Axis of tilt and rotation are in the needlepoint.
The preprocessing of the data consists of data correction
(PRNU, DSNU, offsets) and a (non linear) radiometric
normalisation to cast the data from 16 to 8 bit. All this
procedures can be run in real time or off line. Additional
software parts are responsible for real-time visualisation of
image data, a fast preview for scene selection and a quick look
during data recording.
2.2 The Laser Scanner 3D-LS
In the experiments M2 images were supported by the 3D-LS
depth data. This imaging laser scanner carries out the depth
measurement by side-tone ranging (Wehr, 1999). This means,
the optical signal emitted from a semiconductor laser is
modulated by high frequency signals. As the laser emits light
continuously such laser system are called continuous wave (cw)
laser system. The phase difference between the transmitted and
received signal is proportional to the two-way slant range.
Using high modulation frequencies, e.g. 314 MHz, resolutions
down to the tenth of a millimetre are possible.
Besides depth information these scanners sample for each
measurement point the backscattered laser light with a 13 bit
resolution. Therefore, the user obtains 3D surface images. The
functioning of the laser scanner is explained in (Wehr, 1999).
The technical parameter are compiled in Table 2
507
Laser power 0.5 mW
Optical wavelength 670 nm
Inst. field of view (IFOV) | 0.1?
Field of view (FOV) 30°x 30°
- 2-dimensional line (standard)
- vertical line scan
- free programmable pattern
Pixels per image max. 32768 x 32768 pixels
Range <= 10m
Ranging accuracy 0.1 mm (for diffuse reflecting
targets, p=60%, 1 m distance)
2 kHz (using on side tone)
600 Hz (using two side tones)
Table 2. Technical parameter of 3D-LS
Scanning pattern
Measurement rate
2.3 Applanix POS-AV 510
The attitude measurement is the key problem of this combined
approach. For demonstration we use the airborne attitude
measurement system POS AV 510 from Applanix, which is
designed for those applications that require both excellent
absolute accuracy and relative accuracy. An example of this
would be a high altitude, high resolution digital line scanner.
The absolute measurement accuracy after post processing is
5-30 cm in position, 66=8¢=0.005° for pitch or roll and
Sw=0.008° for heading.
For an object distance D the angle dependent spatial accuracy d
is therefore
d= D-2. (5 inrad).
For an object distance D=10m the spatial accuracy is d=1mm
and appropriate for verification of a mobile mapping appli-
cation. :
For a future mobile mapping system a simpler attitude measure-
ment, which is also less expensive is necessary. For this purpose
we expect in the next few years new gyro development and
improved post processing algorithms.
2.4 POSLAS-PANCAM
Figure | shows the mechanical integration of the three sensor
systems. In the following POSLAS-PANCAM will be
abbreviated to PLP-CAM. This construction allows a precise
relation between 3D-LS and panoramic data which is the main
requirement for data fusion. The 3D-LS data are related to the
POS data as the lever arms were minimised with regard to the
laser scanner and are well defined by the construction.
Figure 1. PLP-CAM
