become "lost" in areas of similar image appearance 
such as reasonably extensive areas of uniform grass 
coverage. Points in these difficult areas did not 
contribute to the model. 
The orthophoto was produced. A grid and title block 
were added and then the orthophoto was printed out 
on an HP Laser Jet printer. 
The test orthophoto map is shown below. 
DMAP Test Orthophoto 
  
  
  
  
  
  
  
Fig. 1 Test Orthophoto Map 
9. PROJECT RESULTS 
The results were very pleasing in that we had 
produced an orthophoto from video imagery using a 
personal computer digital photogrammetric system. 
The resolution of the image was a limiting factor. An 
estimate of the accuracy achieved was about +1m on 
the ground or 4 pixels on the image. 
The imagery was effected by troublesome vibration 
as well as irregular motion of the flight path. The 
vibration most certainly affected the level of accuracy 
achieved. 
The procedure for producing the orthophoto was 
straight forward although the correlation algorithm 
was sometimes limiting. 
162 
10. FUTURE DIRECTIONS 
There are three main steps to be taken in order to 
improve and refine the technique. 
Firstly, geometric restitution can be improved by 
applying accepted techniques such as camera 
calibration or adopting a procedure which minimises 
the need to calibrate. 
Secondly, software with a more sophisticated 
correlation algorithm needs to be used to improve the 
reliability of DEM generation. 
Thirdly, and perhaps most importantly, platform 
stability and positioning needs to be improved 
substantially in order to make the technique more 
efficient. This can be achieved by using a purpose 
built RPV controlled by commercially available 
avionics components previously described. 
11. CONCLUSIONS 
The project has shown that orthophotos can be 
produced from video imagery acquired from a 
remotely controlled aeroplane and using personal 
computer based software. 
It is clear that the future direction is in the adoption 
and use of avionics components. 
The low cost of the technique and its components 
would seem to indicate that possible applications 
such as project mapping for subdivision design, map 
revision, mapping for urban planning, environmental 
monitoring and GIS mapping are limitless. 
12. ACKNOWLEDGEMENTS 
The authors wish to thank the following people for 
their valuable assistance in making this project 
possible. 
James B Oliver of Protectol Pty Ltd for his 
enthusiastic willingness to modify a pristine model 
aircraft for our purpose and the RPV pilots, Noel 
Wilson and Ray Dixon. Joe Van der Maat, Pam 
Kogen and Fiona Bishop from QUT's Audio Visual 
Services Division and lan Hutson from QUT's Visual 
Arts Unit for the supply of the camera and the 
subsequent frame grabbing and video editing. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996 
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