Conclusion - 3D Computer Vision: Efficient Methods and Applications - page 356

photoclinometry are well established with respect to the extraction of regional or
global topographic data of various solar system bodies. Global lunar digital eleva-
tion models (DEMs) obtained based on laser altimetry and stereophotogrammetry
have become available recently. To construct local DEMs of the lunar surface of
high lateral resolution, we have applied the proposed intensity-based methods to the
three-dimensional reconstruction of lunar craters, low wrinkle ridges and faults, and
domes, mainly based on telescopic lunar images acquired with CCD cameras but
also utilising recent images by the SMART-1 and Chandrayaan-1 spacecraft. In this
context we have given an introduction to the reflectance behaviour of planetary re-
golith surfaces. The presented digital elevation maps of lunar craters are of higher
resolution than the available topographic maps, while the extracted basic features
(e.g. crater depth) are consistent with the existing data. A direct comparison has
shown that for the examined lunar domes, the height values obtained with the pro-
posed intensity-based methods based on telescopic CCD imagery are comparable to
those inferred from recent topographic spacecraft data.
In light of the described progress in the field of three-dimensional computer vi-
sion methods and their extensive evaluation in several strongly different real-world
application scenarios, future research directions emerge.
For example, the proposed frameworks for three-dimensional reconstruction of
metallic surfaces should be extended to a determination of the (generally spatially
non-uniform) reflectance properties in parallel with the three-dimensional surface
reconstruction. Furthermore, it will be necessary to take into account interreflections
for increasing the three-dimensional reconstruction accuracy.
In the domain of safe human-robot interaction, the presented methods for action
recognition based on the extracted three-dimensional reconstruction results should
be developed further to increase the contextual and situational knowledge of the
safety system.
The encouraging results obtained with the proposed integrated frameworks for
three-dimensional surface reconstruction furthermore suggest that photometric im-
age information should be utilised in combination with classical triangulation-based
photogrammetric evaluation techniques for the purpose of regional or global topo-
graphic mapping of planetary bodies in the context of future mapping activities.
Possible examples are the construction of detailed topographic maps of the planet
Mercury based on image data from the MESSENGER spacecraft or of asteroids us-
ing images acquired by the Dawn spacecraft. For the Moon, it will be possible to
significantly increase the resolution of existing topographic maps by incorporating
photometric image information.