International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004 
maps as shown in Figure 2 to the farmers, the risk of declaring 
wrong areas can be reduced 
  
   
  
Figure 2. Problematic area, the black outlines represents 
cadastral plots, the white outline the real land use situation. 
In several EU member countries. the LPIS 1s implemented in a 
GIS environment using the digitized boundaries of the 
references as one source and orthophotos as a second one. 
Farmers either will receive maps printed by the LPIS or will get 
Internet access to the system. Therefore proper information is 
made available to investigate the cultivated areas. The Land 
Parcel Identification System in each EU member country has to 
be in production by January 1, 2005. 
1.2 Net Area Determination 
Farmers get financial aid for so-called Net Areas. The Net Area 
is defined as the area, which can be used as arable or forage 
land. Trees, buildings, wasteland etc. inside a reference area 
have to be subtracted. 
      
E s ad 4 
Fa 
Figure 3. Net Areas 
  
The image on the left side with the white outline in Figure 3 
shows the cadastral parcel, the image on the right side the 
parcels Net Area. The information about the Net Area is 
important to a farmer for his declarations. Therefore, this area 
has to be determined and updated. 
2. REVIEWING IMAGE SYSTEMS FOR LPIS 
A great variety of imaging systems, starting from conventional 
aerial cameras to digital airborne sensors and satellite sensor 
systems are available nowadays. For using the imagery in an 
LPIS the ground coverage of imaging systems has to be 
considered, not at least because of economical reasons. 
2.1 Requirements on Orthophotos 
The Joint Research Center, a ‘Directorate General of the 
European Commission (JRC, 2003) defined technical 
requirements and recommendations for the accuracy, geometry, 
radiometry and temporal resolution for orthophotos, to be 
implemented in the LPIS (Léo, O., Lemoine, G., 2001). 
e Absolute one-dimensional RMSE = 2.5m 
(refers to EC regulation 1393/00 (EUR-Lex 2000) 
The orthophoto accuracy should guarantee at least an 
516 
accuracy. equivalent to cartography at scale 
1: 10,000) 
e Pixel size smaller than Im 
e  Panchromatic images (minimum requirement) 
e. Must not be older than five years 
Panchromatic images are of course not a good choice for image 
classification purposes: therefore we will concentrate on 
color/multispectral images in this study. 
2.2 Conventional Aerial Photography 
The JRC also defined technical requirements and 
recommendations for aerial images to be implemented in an 
LPIS: 
e Recommended image scale is 1:40,000 
e The images should be scanned with a pixel size of 20 
um or better. 
(Léo, O.. Lemoine, G., 2001) 
This recommended image scale yields a ground coverage of 9,2 
by 9.2 km? The corresponding flying heights for wide angle 
and normal angel camera are listed in Table 1. 
  
  
  
  
  
  
  
Camera Type Focal length Flying height 
[mm] [m] 
Wide Angle 153 6,120 
Normal Angle 305 12,200 
  
Table 1. Flying heights for standard cameras and image scale 
1:40,000 
2.3 Digital Imaging Sensor Systems 
The advantage of these systems, compared to conventional 
aerial photography, is the option to record simultaneously 
different spectral bands and to deliver the data directly in a 
digital format. The required 1-meter pixel resolution for images 
implemented in a LPIS is directly linked to the aircraft's flying 
height and the ground coverage follows immediately by taking 
the number of sensor elements into account. 
  
  
  
  
  
  
  
  
  
  
  
  
  
Sensor System FOV | No.of | No.of 
[deg.] | pixels per | spectral 
scan line | bands 
ATM (Wide Angle) £3 
2 = SY. FL € ] 
(SenSyTech Inc., 2002) S39 640 ! 
HyMap / ; 
Sont favs DIE 60 si^ 100 - 
Intergated Spectronics Pty. 512 200 
Ltd. (Kramer, 2002) py 
CASI 2 = : 
Ts $12 288 
(ITRES Research Ltd., 2002) | ^ r R 
ADS 40 s 2 
; © : 12.000 5 
(Leica Geosystems, 2002) 81 3 
HRSC AX 29 12172 s 
(DLR, 2002) vult mtr : 
8,000 x 
DMC / ums 
(Z/1 Imaging, 2002) 74 > > 
er a = frame 
  
  
Table 2. Airborne sensor systems 
Table 2 shows a selection of commercially used airborne sensor 
systems. Obviously, the systems cither cover a large area on the 
ground or they record a large number of spectral bands. The 
ground coverage is an important economical factor, whereas the 
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