S which are 
€ mounting 
intersection 
stereopairs 
elationships 
ent (m) 
   
the RMSE 
its average 
n more less 
ersection is 
l'able 3 and 
ition (N,H) 
bout 1/310 
) improved 
t (m) 
| horizontal 
curacy 
rtant to the 
r mapping 
n must be 
rk (Fraser, 
ion on the 
ent station 
ing three 
he height 
Le: they 
group of 
n this case, 
king more 
reased by 
h case of 
1100. 
1e/distance 
on to the 
seline will 
the largest 
| the other 
key factor 
e limited 
perimental 
een done. 
right 
station3 
left 
right right 
station2 | 
! / station 1 
/ / 
left 
  
camera object 
Figure 6 case II: solid spatial intersection 
Table6 The effect of baseline/convergence angle on 
the accuracy of single-stereopair adjustment (m) 
  
  
  
  
  
Baseline 1.107 2.762 7.141 
Convergence Angle 6 16 42 
N 0.0101 0.0071 0.0061 
E 0.0531 0.0252 0.0105 
H 0.0081 0.0032 0.0031 
  
  
  
  
  
  
5 CONCLUSIONS 
Using the low cost system designed in our case, since the 
baseline/distance ratio is very small, the relative accuracy of 
single-stereopair processing is then only about 1/200 to 1/400. 
But if better baseline/distance ratio and  mutli-stations 
adjustment are concerned, this relative accuracy can be 
increased to 1/700 to 1/1000. Because of the using of GPS for 
geo-referencing purpose, no control targets will be needed in 
practice and multi-image with strong configuration can be 
obtained conveniently, and through multi-stations simultaneous 
bundle adjustment higher accuracy and reliability can be 
achieved. It even enables the real-time mapping of complicated 
construction site. 
6 ACKNOWLEDEGMENT 
This research is supported by the Hong Kong Polytechnic 
University (351/616). The authors would like to thank Mr. 
Lawrence Lau for his assistance in GPS surveying and data 
processing. 
7 REFERENCES 
Fraser, C.S., (1997). Digital camera self-calibration, ISPRS 
Journal of Photogrammetry and Remote Sensing, 52(1), pp.149- 
159. 
Fraser, C.S., (1996). Network Design, Close Range Photogram- 
metry and Machine Vision, Whittles Publishing, pp.256-281. 
Karara, H.M., (1989). Non-Topographic Photogrammetry, 
American Society for Photogrammetry and Remote Sensing. 
Li Rongxing, (1997). Mobile Mapping: An Emerging 
Technology for Spatial Data Acquisition, Photogrammetry 
Engineering & Remote Sensing, 63(9), pp.1085-1092. 
Schwarz, K.P., (1995). Integrated Airborne Navigation Systems 
for Photogrammetry, The Wichmann Verlag,Photogrammetric 
week 95, Stuttgart, pp.139-153. 
Schwarz, K.P., and N. El-Sheimy, (1996). Kinematic Multi- 
Sensor Systems for Close Range Digital Imaging, International 
Archives of Photogrammetry and Remote Sensing. XXXY(B3), 
pp.774-785. 
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