Step 7 transfer to GIS system 
Results are read back from the AED into an output 
file with fiducial marks, codefilled polygons and 
boundary lines that can now be transferred to an 
appropriate pixel input programme of the selected 
GIS system. 
At ITC, the first use of ADIOS will be to input data 
in the raster oriented,ITC developed, USEMAP 
geoinformation system. 
In that case USEMAP software will 
a) apply a geocorrection 
b) eliminate boundary line codes by attributing 
line gridcells to the appropriate landuse 
polygon 
c) resample to the regular gridcell size for the 
project area. 
5.4 Geocorrection 
In flat areas geocorrection will be based on digital 
rectification, defined by matching tiepoints on the 
photo with points on a map or from a list with known 
coordinates. Such data will be stored in a photo 
index file and after linking this file with the 
observed fiducial marks in the scanfile the 
geocorrection can be applied as part of the 
resampling procedure. If various overlays of the 
same photo have to be entered the same photoindex 
file can be used. 
In gently rolling hilly areas digital facet plotting 
can be used in a similar way to digital 
rectification. In mountaineous areas also correction 
based on digital monoplotting can be used, provided 
that a digital elevation model can be made 
available. 
It is also possible to vectorize the data first and 
then to apply the geocorrection on the vectorized 
data as has been done by LEBERL and CHRISMAN. 
5.5 Improvements and extensions of the current pilot 
system 
To enhance the quality of the "row" scanned data it 
is planned to improve the lighting system. 
Automatic gap-closure is currently under study and 
some form of vectorizing will be implemented soon. 
Possible approaches in this field have been 
described by PEUQUET (1981) and HARRIS et al. 
(1982). It is expected that in the near future 
topologically encoded vector data will be derived 
from the scanfile after processing in the 
rasterdomain only. 
6 DIGITIZING OF OVERLAYS VS INTERACTIVE DIGITIZING 
DURING INTERPRETATION 
Several USEMAP programmes have been designed to 
digitize during the actual interpretation (DE 
BRUIJN, 1983). 
Experience so far has shown that it is a good and 
efficient method for 
a) "point" data e.g. houses 
b) selective landuse data 
For complex landuse interpretations that cover a 
full photograph there is a preference to interpret 
first on an overlay and then to digitize that 
overlay in a separate step. 
One of the theoretical advantages of interactive 
digitizing during interpretation is that it should 
be possible to query the database e.g. to ask for a 
previous interpretation to assist in change 
detection. Due to lack of software development 
capacity this possibility has not been implemented 
so far at ITC. 
When ADIOS becomes available it may be assumed that 
most general landuse type digitizing will be carried 
out automatically. 
Apart from saving time and avoiding errors it has 
the big advantage that it does not interfere with 
traditional photointerpretation methods (the 
production of an interpretation overlay) and does 
not require digitizing training or the use of 
digitizer operators. 
For certain corrections or certain types of change 
detection interactive digitizing will remain a 
valuable technique, but clearly complementary to 
automatic digitizing. 
However, for "point" type date the production of a 
readable and reliable overlay is not without 
problems and there interactive digitizing seems for 
the time being the most efficient solution. 
7 FURTHER APPLICATIONS OF THE DIGITAL CAMERA 
The high number of greylevels that can be scanned 
with the Eikonix makes it possible to scan airphot.os 
with a fairly good image quality. A typical 55 x 55 
mm SFAP negative can be scanned with 37 lines/mm 
resolution, a 9 inch photo with 9 lines/mm. 
This creates several new possibilities: 
The photo can be scanned and then displayed (if 
necessary after geocorrection) as a background to 
the landuse data on an interactive workstation. This 
might be a good method for updating such data or for 
detection of errors. 
Displaying a scanned photo on a screen enables also 
interactive interpretation where interpretation 
results can be displayed immediately. This can be 
useful in situations where airphotos are used to 
count items, like in housing studies and recreation 
surveys. The marks on the screen avoid double 
counting and allow an easy check on forgotten cases. 
A step further is the production of digital 
rectifications or digital orthophotos. Using the 
geocorrection methods described earlier this is 
clearly feasible as has been demonstrated already by 
KONECNY in 1979, who used a photo scanner with a 0.1 
mm pixel size. Low cost, medium resolution output, 
acceptable for a number of applications can be 
generated by the new generation of laser printers 
with 300 dpi resolution enabling 15-20 points/cm 
printrasters to render appr. 20 greylevels. An 
output quality that is better than that of the 
photocopies that are now increasingly used as field 
material and for provisional basemaps. 
8 CONCLUSION 
Although the results of the pilot system are still 
limited at the moment this publication had to be 
finalized, they show clearly that the approach is 
successful and that an operational system can be 
developed in a rather short time, using the 
available experience with USEMAP geodata processing, 
image processing and photogrammetry in ITC. 
Developments in the computer industry where low-cost 
resolution graphic input and output devices are 
rapidly becoming available make it probable that 
such developments will have a considerable impact on 
the application of photo interpretation and its 
integration in modern geodata environments.