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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004 
LIDAR heights over the test area is about +0.20m which is 
slightly larger than the published height standard deviation of 
the system (+0.15m). Regarding the planimetric accuracy, the 
computed offsets in the scanning direction over the test area 
show two main outcomes. First, the planimetric uncertainty is 
larger (almost double) at the end of the swath than at the 
middle. So in general, the planimetric accuracy seems to vary 
based on the location along the swath width. At the end of the 
swath width the average offset was about 0.60m, while at the 
middle it was about 0.30m. The second outcome is that the 
whole strip seems to be shifted in the easting direction since all 
the computed offsets have the same direction. 
Both accuracies, relative and absolute, show two types of 
variation. The first variation form is the short period random 
variation which has a high frequency with time. This random 
variation seems to represent the actual precision of the LIDAR 
system. The other variation form is the long period variation or 
“a trend”. This trend has a much lower frequency and seems to 
be as a result of the error in the positioning system. If this trend 
is modeled and the data is adjusted accordingly, the accuracy of 
data will be improved. Testing more samples that cover 
different parts with a longer period of time is needed to verify 
these conclusions. 
ACKMOWLEDGEMENT 
The authors would like to acknowledge the support for this 
research from the following organizations: the Army Research 
Office and the Topographic Engineering Center. 
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