INFORMATION 
OPTICAL DETECTION IN TOPOGRAPHICAL MAPS 
DIGITAL ACTUALISATION PROCESS 
Prof.Dr.Eng. Niculae Ráducanu 
Eng. Dan Räducanu 
Romanian Society of Photog.& R.S. 
Bucharest, Romania 
ISPRS Commission IV (WG IV/3) 
ABSTRACT : 
Àn optical method for planimetric elements changes detection needful in digital 
actualisation of topographical 
maps, the paper aims to present. 
The optical correlation 2D principle stays as basis of photogrammetric information 
processing method, using Fourier transformation holograms from aerial or cosmic photo- 
gramms , 
KEY WORDS : Optical Detection, 
One of the principal charge of the topo- 
geodetic assurance is the topographical 
maps actualisation. Though is a problem 
as old as mapping is, in contemporany 
conditions with automatically topogra- 
phical maps processing by using aerial 
and cosmical records, this process 
acquires new aspects using automatic 
processing data systems, geodetic data 
basis and the digital topogeodetic model 
of the land, as well. 
Actualisation maps process of two princi- 
pal operations is composed : changes 
arised on the land from the map detec- 
tion - on the hand, and map correction on 
the other hand, It is demonstrated by 
experience that approximately 40 % of 
the work time is used for changes detec- 
tion and the last 60 % for the actuali- 
sation in fact. 
Changes detection used method consists 
in photogram transformation from central 
projection in to the orthogonal one at 
the map scale,or data transformation 
(from geodetic data basis) into photo- 
grams and comparing with the actual one. 
Transformation can be made by rectifica- 
tion, orthophoto rectification or by 
image digital processing. 
More simple and rapid methods can be 
used for changes detection and maps 
actualisation due to appearance of geo- 
detic data basis, permitting automatic 
maps realisation. 
An optical method of planimetric 
elements changes applying bidimensional 
optical correlation method based on 
Fourier transformation holograms of the 
photograms, the paper aims to present. 
1. DETECTION OF AREAS AND 
PLANIMETRIC ELEMENTS TO 
BE ACTUALISED 
Optical bidimensional correlators of 
information can be succesful applied in 
corresponding images selection, fact 
showed by recent studies regarding 
optical methods for information proce- 
ssing. It does not ask an exterior 
correlation compute because of simulta- 
neously, by illumination optics, 
corelation compute physical realisation. 
514 
lap Revision, Photogram - Hologram 2D Correlator. 
Optical correlation advantages can be 
finalised by using the coherent light, 
transformation properties of lens and 
holographical methods for Fourier 
transformation of the photogramms 
recording. 
There is two optical methods used in 
images correlation : the correlation 
image-image and the correlation image- 
fitting filter (hologram). Image-fitting 
filter correlators are used in corespon- 
ding images detection, optical filtering 
and parallaxes measurement. 
1.1. Image-fitting filter correlator 
  
By using this correlator is realised the 
optical transmision of a point from the 
Fl photogram through his transformation 
on the second F2 photogram of the new fly 
and the correlation sign in the external 
focal plane is computed and presented. 
The optical assemblage for the bidimen- 
sional working in the Fig.l is presented, 
Signal Beam 3 
    
  
  
  
  
Fig.l. Holographical models restitution 
in the bidimensional correlator. 
The Fl photogram in the first focal plane 
is placed, and the hologram of the F2 
photogram Fourier transformation (from 
the actual fly) in the subsequent focal 
plane of the first lens. 
To detect corresponding images, the F1 
image with an laser collimated fascicle 
of 100 mv power is lighted. 
After that the Fl photozram Fourier 
transformation arised in the first lens 
focal plane and is multiplied by the F2 
photogram sp cial filter representation.