predicted positions are such that two targets will overlap or if a 
target will be obscured by the surface. The structure of the 
mesh can also be used to predict when the target will reappear 
and thereby resume lock on the target. This research is still in 
the formative stages, however, re-processing of the Fresnel lens 
image sequences has indicated that the technique reduces the 
frequency of loss of lock on targets during the tracking. 
5. CONCLUSIONS 
This paper has presented two cases of characterisation and 
tracking of membrane surfaces at NASA Langley Research 
Center. The effectiveness and versatility of photogrammetric 
techniques to provide precise and reliable information on 
dynamic surfaces has been demonstrated. Notwithstanding this, 
further improvement in the reliability of target tracking is 
possible using techniques such as the interpretation of a surface 
mesh. 
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