International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B1. Istanbul 2004 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
model of the 3-DA S-1. Figure 3 shows an evaluation of the Table 1. Lens distortion data 
modulation transfer function for this lens. : = 
Pixel Angle Dist. 
4150 1.023 -0.001 
KF af ratio 8.852 f/ 46 4350 2.047 0.001 
MF IX! a — 7.5 15.0 300 $0.8 Lp/m = = 
see = : p 4550 3.070 0.004 
vo ft es 4750 4.088 0.001 
* " i. - ü * ii 4. De t a 
uel. . | "Lu. à T 4950 5.108 0.006 
a, te——— ol i 5150 | 6120 0.003 
Sj ^ bet FON S530 [715 0.008 
])se bo o v GEM fund e us ™ 5550 8.136 0.004 
sa b ETC ER MET TAROT 5750 9.136 0.003 
40 | | | | M 5950 10.132 0.005 
RT i i i ; i 6150 11.118 0.001 
20 : P. 6350 12.100 0.000 
18 1 1 1 t 6550 13.074 -0.002 
B ld i d omes 6750 14.040 -0.004 
"a s s NS dct Ba 6950 14.999 | -0.004 
imr ciicin ‘odie {ami 
7150 15.949 -0.005 
; ; 7350 16.891 -0.004 
Figure 3. MTF for 100mm lens 7550 17.824 70.004 
7750 18.749 0.001 
The3-DAS system software runs under Windows XP. The 8000 19.885 0.002 
scanner electronics, designed by Geosystem, is in firmware and 
Table 2. Lens distortion data 
thus upwardly mobile with technical developments and future 
requirements. The transfer of image data from the sensor 
electronics to the computer is by the Camera Link standard, at 
12 bits, to a PCI -X 64 bit line grabber. The camera link also 
provides a control channel and the downloading of new 
firmware. Tests show that data from all 9 lines can be 
simultaneously recorded to disk at 800 lines per second. A 
suitable computer with adequate mass storage for a typical 3-4 
hour should host the system. The geometry of the convergence 
has the central camera looking at nadir, the forward looking 
camera inclined at 26 degrees, and the after looking camera 
inclined at 16 degrees. This provides two channels with 
conventional base-height configuration, and a third channel to 
provide additional, redundant parallax, but also to provide fill - 
in in case momentary turbulence degrades the nadir channel. 
Measured lens distortion data are shown in Tables | and 2. The 
angles are decimal degrees and the distortion is in millimeters. 
Figure 4 shows a block diagram of the system. 
  
  
DAS Camera 
  
  
  
  
  
  
  
  
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“4 
  
i 
ix wancmm | | 
eie enun B 
i i 
Figure 4. System block diagram 
Intei 
  
Early computations indicated that existing stabilized platforms 
  
  
  
  
  
  
  
Pixel Angle Dist. designed for use with film cameras were not accurate enough 
150 -18.750 | -0.002 for use with aerial three line scanners. This prompted us to 
350 -17.825 0.002 design a new stabilized platform, ASP-1. Our platform is a 
550 -16.893 0.001 very simple kinematic design where the pitch and roll actuators 
750 -15.950 0.003 tilt the camera adapter plate as commanded by the IMU 
950 -15.000 0.002 module. Initial evaluation for this platform indicate an 
1150 -14.040 | 0.004 accuracy of 0.02 degrees for pitch and roll, and 0.05 degrees for 
1350 -13.074 | 0.000 yaw. À unique feature of this new platform is the capability 
1550 "12.100 0.000 (for frame cameras) to provide forward motion compensation, 
1750 11.118 0.000 FMC. We consider the ASP-1 to be an integral module of the 
1950 “10.130 | -0.003 3-DAS-1. Compatible IMU-GPS systemswould be the 
Applanix 410 or 510. Integration is also being made with the 
  
  
  
  
  
  
  
  
  
  
  
  
2150 -9.136 -0.003 Trackair Flieht M S 
2350 3157 1.006 rackair Flight Management System. 
2550 aes D006 An overview of software for the 3-DAS-1 is summarized in the 
E ro- zv: following lists. 
2950 -5.107 -0.005 
3150 -4.092 -0.008 DAS scanning software: 
3350 -3.071 -0.005 *  Compresses and displays grabbed image in real-time 
3550 -2.046 0.000 mode, allows to switch cameras while running. 
3750 -1.024 -0.001 * Builds histograms for every camera image in real- 
  
  
  
  
  
3950 0.000 0.000 time mode. 
  
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