255
Fig 2. Taking a stereo image
to
al
1e The image data that are obtained by taking a pair of
te images(a stereo image:Fig.2) with the high-resolution CCD
al camera are stored on two optical disks, one for the right and
ot the other for the left. The PI-1000 measures accurately 3D
of objects by using the digital image information obtained from
i these optical disks.
Or
ái 2.2 High-resolution CCD Camera (PC-1000)
à The high-resolution CCD camera consists of a camera unit,
ür a control unit and a personal computer. This CCD camera
employs the linear CCD scanning method. The specifications
of the CCD camera are shown in Table 1. And Fig. 3
illustrates the inner configuration of the CCD camera. Its
characteristics are as follow:
D The resolution here is equal to that of a 35mm film camera,
ng ie., 16.77million pixels with pixel size being 7 Æ& m (a
nd square).
3D Q Scanning accuracy held to a fraction of a pixel by
employing 1 4m linear encoder of high precision(Fig.4).
By means of employing a linear slide, which has high
straight line accuracy for driving the lens, the fluctuation of
the principal point is kept down to 3 4 m or less, and the focal
adjustment (which was formally impossible) is finally made
Tablel. Specifications
Image acquisition|Linear CCD scanning
method method
Number of pixels 4096 X 4096 pixels
Pixel size 7X74m
Image zone size 28.7 X 28.7 mm
Image acquisition {4sec or more
time
Gray scale resolution |8bits
Lens f35mm F2.8
Scanning accuracy + 3 UM or less
Fluctuation of|X 3 um or less
principal point
Adjustment of focal point |Manual and automatic focus
Exposure control By aperture ‘and CCD
integration time
Viewfinder Exterior LCD and optical
viewfinder
Image storage media DAT (128 images / tape)
Power supply DC power supply
Dimensions 160X150 X 250mm
Weight 4kg (camera unit only)
Lens unit
Focal
Adjustment
= €—> Scanning
FH
CCD stage
7 CCD
Lens stage
Fig.3 Inner configuration of CCD camera
possible. Also, by means of a micrometer with a 2.5 4 m scale for focal adjustment, measurement is conducted with
high precision. The deviations from scanning accuracy and
fluctuations of the principal point both owing to
temperature are merely 1 4 m/20 C, making the characteristics Q and © of the aforementioned highly reliable.
@ As the camera is provided with an image processing LSI, which has been developed by our company,
magnification, reduction, rotation, perspective projection, etc., of the image can all be conducted by the camera
itself. Further, the image can be confirmed on the monitor in real time. Fig.5 shows a block diagram illustrating the
electric system.
f >
Accuracy
2-31
max
je
-
10 20
Feed amount from
origin of scanning(mm)
=10
(um)
o]
of ET
Fig.4 CCD scanning accuracy
5 A
CCD
focus
aperture
Fig.5 Block diagram of electric system
25 IAPRS, Vol. 30, Part 5W1, ISPRS Intercommission Workshop “From Pixels to Sequences’, Zurich, March 22-24 1995
