Full text: XVIIIth Congress (Part B2)

  
  
  
  
  
. o, [pixels?] N. of iterations Max error 
Test 
Slope 0 1.38 107? 10 110? 
Slope 0.005 1.58 102 10 1102 
Slope 0.03 1.15 102 10 21072 
  
  
  
  
  
Table 2: bundles adjustment results. 
The determination of the ground point coordinates in the 
simulations lead to the following results 
(AZ = Z (estimated by the plotter) —Z (a priori known)): 
  
  
  
  
  
  
  
  
  
Test Max error | mean AZ mean formal 
AZ 0, Std Dev of Z 
Slope 0 0.0 0.0 : «107? 
Slope 0.005 0.296 -0.004 0.0029 0.006 
Slope 0.03 0.042 -0.003 0.0004 0.006 
  
  
  
Table 3: plotting results. 
5.2 Tests on real objects 
In these tests only approximate orientation parameters 
and object shape are known. 
Three images of a cilindrical object with radius of 
approximately 30 cm are taken by a CCD camera, as 
shown in the following scheme. 
E Y Y 7 7 
\ ‘ ‘ i : 
bd 
Figure 4: taking scheme 
The digital images are obtained with a frame grabber with 
no special care for clock alignment and a resolution of 
640x480 pixels. 
Least square matching results are satisfactory, with a 
standard deviation of the adjustment among 107$ and 5 
1073, and standard deviation of the image coordinates x 
and y less than 0.110 e 0.085 pixel respectively. 
Images orientation is performed setting a conventional 
reference system fixing all the orientation parameters of 
the first image and the Xo coordinate of the third. The 
procedure is performed with a standard deviation of 
0.102 [pixel] and 10 iterations. 
In this test a "ground truth" is not avilable to check the 
real precision of the procedure. To evaluate the results, 
besides a first qualitative judgment of the plot of the 
obtained points as shown in the image below, a 
parametric model of the surface has been built. 
422 
  
Figure 5: obtained surface. 
Assuming that the plotted points belong to a cylindrical 
surface it is possible to esimate in a least square 
procedure the five parameters that describe the cylinder's 
size and its position in space. 
It is now possible to estimate the distance of each point 
from the surface. This value can be considered the error 
of the determination of that point. For the points in the 
tests this error has a mean of 0.147 mm and a standard 
deviation of 5.056 mm, the number of points is 518. 
6. CONCLUSIONS 
The system that has been described can be considered a 
prototype of a complete digital photogrammetric system. 
Several test of different digital photogrammetric 
techniques, not described in this paper, have been 
carried out to select those suitable for real applications. 
The development of the user interface is carried out 
thinking of a real production enviroment, giving the user a 
simple, consistent and standard interface, as well as 
default values for most of the required parameters. 
The simulated tests show the functionality of the system; 
the real test shows the precision of the overall procedure 
that, taking into account the quality of the images, can be 
considered satisfactory. A further step in the 
development of the system will be the integration of the 
digital sensor calibration techniques, currently under 
study at our laboratory. 
7. SELECTED BIBLIOGRAPHY 
1. Papers about researchs developed in the same 
department and related to the present work: 
Benciolini, B. 1990. The Observation Equations of Digital 
Phototgrammetry. ^ Proceedings of the ISPRS 
Intercommission WG 3/6 Tutorial: Mathematical Aspects 
of Data Analysis, Rhodes, Greece. 
Benciolini, B., Sguerso, D., 1996. Digital image matching 
in photogrammetry. Bollettino di Geodesia e Scienze 
Affini, anno LV, n. 2, pp.178-190. 
Zateli, P., 1994. Progetto, realizzazione e 
sperimentazione di un sistema fotogrammetrico digitale. 
Bollettino della SIFET, n. 3, pp. 135-154. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996 
nS 
—— pease Mm NN — 
IN "TS 73 “WW 
PP 
Q) Mm 
Q) hmmm OD) YY 
O £73 
mo oO
	        
Waiting...

Note to user

Dear user,

In response to current developments in the web technology used by the Goobi viewer, the software no longer supports your browser.

Please use one of the following browsers to display this page correctly.

Thank you.