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3D shape recovery from the stereo data was also
investigated using the DI3D
TM
software. We
considered three main issues which may affect the
stereo software to obtain 3D shapes of bats such as:
1) lack of texture on bats’ bodies; 2) occlusion of
body parts; 3) motion blur. Our experiments so far
have shed some light on these concerns. Firstly, it
was found that the texture of bats could be revealed
under proper illumination. Fig.7(b) shows a bat
head’s fine texture when the bat flew through the
working range of the sensor on which the IR light
was concentrated. With the texture visible to the
cameras, the stereo software was able to recover part
of the 3D geometry of the bat head as shown in
Fig.7(a). Secondly, motion blur did take its toll on
3D shape recovery. For instance, the bat’s head in
Fig.7(a) was smoothed with some fine shape details
missing. Thirdly, the effect of occlusion was
evident. For instance, the bat’s ears were squeezed
onto the head in Fig.7. Despite these defects, the
results show that it is possible to recover 3D shapes
of bats using stereovision methods.
5 CONCLUSIONS
This paper reports an application of using a 500 fps
stereovision sensor to capture 3D external
morphology of bats in flight. We discussed the data
acquisition scenarios and evaluated the performance
of the sensor accordingly. Stereo data were acquired
from four species of live bats, and the preliminary
analysis of the data confirmed that it is feasible to
obtain 3D shape information of bats in flight for the
chosen species using the stereovision method at
500fps. A number of issues were revealed in 3D
shape recovery related to motion blur and occlusion,
which helps identify the problems we will be
working on and revise the expectation of quality of
3D measurements we can draw from the stereo data.
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