ul 2004 
atching 
ifferent 
ult. in 
"rtunity 
  
  
and 
pacing 
fferent 
GPS 
inually 
ure 7) 
"menos 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
  
Figure 8 and Table 1 show the comparisons between each 
automatic DTM (correlated points) and a manually measured 
one. In both the b) and c) cases, using seed DTMs does not 
improve substantially image matching results. Similar 
conclusions were obtained for the other test areas. 
In our case of study. indeed, it was possible solving DTM 
mistakes only by a post editing process. In particular, in the 
neighbourhood of structures, top-and-base breaklines were 
introduced; instead, in some sandy arcas, manual editing was 
conducted point by point. 
274024 274026 274028 274030 274032 274034 274036 274038 
AO + 
seh ++ 
  
    
     
3269594 + ; 
  
3269592 
3269590 - 
  
  
3269588 | x 
  
  
  
  
3269586 
3269584 | # 
32695824 
  
3269580 
  
3269578 | + + 
dt. 
3269576 
  
  
  
  
  
  
  
  
  
  
  
3269574 
2) + 06% + 562% + 259% + 179% 
274024 274026 274028 274030 274032 274034 274036 274038 
    
    
* * 
EROR CER T . 
32695964 + + .-Ft RT 
+ + + s 
.+ + + 
+ + 
32695044 
| fod 
3269592 
3269590 * 
| 
3269588 
3269586 
3269584 | + 
3269582 - 
3269580 
3200578] +} 
T 7 
3269574 | T oed 
b) 4 03% + 558% + 239% + 20% 
al 
    
  
274024 274026 274028 274030 274032 274034 274036 274038 
Mp > + 
+de + 
3269596 + 4 * 
3269594 ' 
3269590 
3269588 
3269586 
3269584 
3269582 
3269580 
3269578- 4 
3269576 
3269574 
e 4 + 
oF 09% 4 569% + 247% + 175% 
+ La 
  
- -2 to -0.3 4» -0.3 t0 0.3. 4 0.3 to 0.6 + 0.6 to 3.5 
  
  
  
Figure 8. Test area: classed plot of residuals (m) between 
automatic and manual DTMs. Black dots represent seed points. 
  
  
  
  
  
a) b) C) 
Minimum -1.89 -0.54 -0.94 
Maximum 3.04 3.00 2.53 
Mean 0.34 0.36 0.33 
Standard deviation 0.39 0.37 0.35 
  
  
  
  
  
  
Table 1. Test area: statistical summary of residuals between 
automatic and manual DTMs (values in m). 
Finally, we compared the elevation data coming from kinematic 
GPS survey with those deriving from photogrammetric DTM. 
As in above reported tests, +30 cm was considered the 
maximum tolerable value for the differences between GPS and 
photogrammetric elevation data. That limit comes from 
considering the image scale, the mean stereoscopic base of 
about 40 m and the pixel size. 
Observing figure 9, showing a portion of the comparison, it can 
be noted that the higher inconsistencies are localized around 
West temenos wall. This trend is explainable considering that 
this area is covered only by two images with a little stereoscopic 
base (about 10 m): in such condition we could accept up to +1m 
differences. Such a problem stresses that small format low- 
height photogrammetric systems do not allow for an accurate 
control of the base and of the flight height. 
As for the rest, however, differences are acceptable except for 
really localized problems coming from structures or shadows. 
The DTMs study has therefore showed the effectiveness of ATE 
module in producing digital surfaces; it must observed that the 
automatic procedure can give problems when the aim is the 
contour representation, because image matching extracts points 
without an interpretation of object morphology.