The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part BL Beijing 2008 
improved filtering accuracy. It is expected that automation of 
this method will make the examination process more efficient. 
Up to now, examination of the filtering has had to be done by 
an expert as it involves making reference to contour lines and 
orthophotos. With the new quality control method, a non 
expert will be able to examine the filtering because there are 
clear criteria for the interpretation of abnormalities in the 
filtering. 
Automation will also lead to the elimination of oversight in the 
examination process, and thus is expected to improve the 
efficiency of the work. 
As this new quality control method does not require 
orthophotos, it will have a positive effect on shortening the 
work period. However, orthophotos are not absolutely 
unnecessary. A monochrome shaded map has some areas 
where the topography is unclear, the reference to the 
orthophotos is necessary when filtering such areas. 
A problem remaining to be solved is the need to examine more 
than one map. The authors have tried the method of presenting 
a layered display of ground data in black and white on a color- 
shaded map. However, this method has been abandoned as it 
was not possible to interpret topography or point clouds on the 
background. In future, it is hoped that a QC/QA map will be 
developed on which both the ground data and micro topography 
can be represented on a single sheet. 
REFERENCES 
Vu,T.Thuy,2004.Filtering Airborne Laser Scanner Data. 
Photogrammetric Engineering and Remote Sensing, 70(11), pp. 
1267-1274. 
Sasaki, H., 2007. The Development of ELSAMAP (Elevation 
and Slope Angle Map) for Geographical Features Interpretation. 
APA, 93, pp.8-16. 
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