anbul 2004 International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004 
4. REFERENCES 
Fahmi Amhar, Josef Jansa, Christine Ries, 1998. The 
Generation of True Orthophotos Using a 3d Building Model in 
Conjunction with a Conventional DTM. IAPRS, Vol. 32, Part 4 
"GIS-Between Visions and Applications", Stuttgart, Germany. 
'c footprint 
he areas on 
raster data 
Jiann-Yeou Rau, Nai-Yu Chen, Liang-Chien Chen, 2000. 
Hidden Compensation and Shadow Enhancement for True 
Orthophoto Generation, Proceedings | of | ACRS2000. 
http://www.gisdevelopment.net/aars/acrs/2000/ts4/digi0003.sht 
ml 
lata into a 
Intersecting 
rage place 
polygons is 
mbiguously 
je through. 
es part of 
nage. 
of elevation 
m from the 
  
Fig. 5: "True ortho" image with hidden areas recovered from 
| orientation overlapping image. 
led for the 
ing because 3. CONCLUSION 
> number of 
lowever, in 
ger than the 
rcraft) is far 
akes just a 
generation. 
3.1 Benefits of the Proposed Method 
e Significantly smaller memory usage. There is no need 
to allocate large distance/identification code matrices. 
e Resolution independent. It explicitly generates hidden 
area features as vector data. 
e Further analysis (seanilines generation) and elevation 
model validation are easily accomplished based on 
the vector data. 
3.2 Implementation Advantages 
* Allows easy integration of hidden areas compensation 
techniques with existing software (Z/1 Imaging 
ImageStation OrthoPro software). It is just an 
additional step in a standard workflow. There is no 
need to modify existing raster operation. 
*  Hfficiently uses Intergraph GeoMedia Topology API 
for all complex geometry manipulations. 
33 Future Work 
e Update the current surface triangulation storage 
format to provide more accurate building model 
representation. 
* Optimize elevation model creation workflow to 
provide simple and precise way to digitize building 
roofs, bridges, etc. 
* Apply the same polygon-based hidden area detection 
technique for shadow zone detection and 
enhancement. 
* Adopt the true ortho technique for line scanner 
d blue imagery. 
  
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