Full text: XVIIIth Congress (Part B3)

     
we arrive at 
  
   
   
  
  
A comb 
  
   
   
   
      
     
  
     
   
  
  
  
  
  
     
  
   
    
  
  
  
    
     
   
    
     
    
      
     
    
   
    
(sidelap 
AED Ach 4f OM corner - 
xi (AT PA) ! (AT PU & A- N)). (5) SE 
Using a global term AN = 4- N for the improvement in Bi 
direction to the satellites one yields m 
16 + 
xl- QA" P1+QA" P(AN). (6) “i 
12 Fi 
The design matrix contains the direction cosines of each 
observed satellite (geometric information) and reflects 
ambiguities and cycle slips. 
To keep the number of additional ambiguity terms small, 
only those, which could not be fixed reliable in the GPS 
processing are improved. Therefore, coordinates with 
‘improved’ ambiguities can be computed from a ‘forced’ 
coordinate estimation done by the GPS processing 
software and improvements of the coordinate estimates 
  
  
  
  
  
1000 me — 
Figure 6: used satellites block Oesingen 
horizontal lines: continuously used satellites 
Figure 6 gives an overview about the used satellites in 
the block Oesingen. 10 flight strips have been used. The 
  
  
  
  
  
  
  
  
  
  
  
  
  
10 + 
  
  
  
lo d ; satellites 1, 3, 4, 6 and 7 could be used without cycle slip Figure € 
AN "from the combined bundle adjustment: over the whole flight time, satellite 9 was not used in the A wi 
first flight strip. The other satellites have been used only B: col 
S proved EE ed + Ey (7) in one flight strip. The satellite number in figure 6 does C: col 
not correspond to the numbers of the GPS-satellites, they 
For this GPS error model - some ambiguities already are only internal numbers. After a cycle slip the internal Figure 
solved, some still not reliable fixed, but forced to integers —— Satellite number is changed. The satellite 14 is not used adjustm 
- the corresponding design matrix is evaluated to be in the whole strip 8. In the traditional method of system 
incorporated into a combined bundle adjustment. The combined block adjustment this can cause an hand si 
new GPS model for remaining systematic GPS errors inhomogeneity of the solution, with the new approach photos 
can be handled by the software packages GEONAP and also this satellite can be used. configu 
BLUH. method 
14 ; var cn traditio! 
5. EMPIRICAL RESULTS NV) E distance in flight direction — samedi 
ied | P^ WM the olc 
The new approach was applied to the data set | | +9.5cm 
‘Oesingen’. In a first processing of the GPS data all | The res 
ambiguities and cycle slips are estimated and fixed, if the | | andas 
ambiguity resolution algorithms have succeeded using iil | The ho 
stochastic criterion's. One satellite was badly corrupted AE da A BS M J Bf both m 
by cycle slips and rejected completely from the GPS cul | WMA / genera 
processing. In total 18 ambiguities/cycle slips are present Br X is stabl 
for the complete block. However, 4 ambiguities could be | = control 
reliable fixed using the stochastic properties of the vd Mn ^ DX block v 
GEONAP processing software. pe 0 10000 20000 20000 40000 50000 60000 70000 80000 mam | is not § 
Te m combir 
Figure 7: Differences GPS-positions against projection becaus 
UU. nee Eg A "d dh centers determined by reference adjustment with BLUH ii ai 
+ PE ar Hep. CE uk rcd The differences between the interpolated GPS-positions Is reac 
co Ho ans ti este ull ie and the projection center coordinates determined by Improv 
sre datei ar i A tao bundle block adjustment without GPS-data are shown in : 
im ; ue figure 7. The offset of the GPS-antenna was not Beside 
DE GEE Fi recorded, but it can be seen in figure 7 as -1.2m in X and calibra 
et ee ES 0.15m in Y. In addition the typical changes depending introdu 
PA A e Ek upon the flight strips are obvious. A fitting of the compo 
3 o o differences individually for every flight strip by constant antenn 
i As a aE Tor a tr values (shift) yields to RMSX=+9.1cm, RMSY=+9.2cm flown i 
aT ar TE Eee and RMSZ-44.3cm. A linear regression (drift) reduces unkno 
D eq iem eee m à the differences only to RMSX=+9.1cm, RMSY=+9.1cm : 
3 E and RMSZ=+3.7cm. The differences are not only caused 
Design Vue by the GPS-positioning, the root mean square of the 
projection center accuracy determined by block The i 
Figure 5: block Oesingen with control and check points adjustment is RMSXo=+5.2cm, RMSYo=+5.7cm and depo 
140 photos, image scale 1 : 8000, f=153mm RMSZo=+2.8cm. ane. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996 
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