230
P. Drap et al.
14.2 Photogrammetry: Dense Map
To model the environment by photogrammetry in an unsupervised way it is first
necessary to automatically orient a set of unordered images. This orientation phase,
which is crucial in photogrammetry, as computer vision, has seen the past three
years a great boom. The problem was first solved in the case of ordered series of
photographs, for example, made a circle around an object and recently in the case
of photographs unordered (Barazzetti et al. 2010; Shunyi et al. 2007). Once all the
photographs are oriented several methods are proposed for producing a dense cloud
of 3D points to represent the area photographed.
Two major families of methods exist. Those that use solid models as the voxels
(Furukawa and Ponce 2010; Zeng Gang et al. 2005) are based on the discretization
of space into cells and the goal is to discriminate between full and empty cells to
define the boundary between them. The advantage of this method is to use lots of
photographs taken from arbitrary viewpoints. In contrast the delicacy of the final
model depends on the resolution of the voxel grid can be RAM consuming. On the
other hand methods using meshes could adapt their resolution to better reconstruct
the details of the scene (Morris and Kanade 2000).
Also the work of Furukawa and Ponce on the dense map generation (Agarwal et al.
2010; Furukawa and Ponce 2010) have also resulted in open source publications.
We use this work, merged with our own photogrammetric software in order to use
calibrated camera and some constraints on the bundle adjustment, for several months
and some examples are presented in this paper.
These developments were coupled with a software bundle adjustment of operating
on an unordered set of photographs are based on an implementation of SIFT on GPU
due to Changchang Wu, University of Washington (http://cs.unc.edu/ccwu/siftgpu)
and implantation of developments PhotoTourism (Agarwal et al. 2010; Snavely et al.
2010). The bundle adjustment used is based on the Sparse Bundle Adjustment of
Lourakis (Lourakis and Argyros 2009) and a version of the bundle adjustment of a
set of unordered photographs is available in open source: Bundler software (Snavely
et al. 2010).
On the other hand, since 2007 IGN (Institut Géographique National, in France) has
decided to publish in open source the APERO MICMAC software, dedicated to the
automatic orientation of an unordered set of photographs and the calculation of the
automatic mapping on a set of photographs oriented. (http://www.micmac.ign.fr)
(Pierrot-Deseilligny and Cléry 2011). Their approach is more rigorous from a
photogrammetric point of view and allows using calibrated camera.
14.3 Acoustic Survey
The acoustic survey is mainly useful to produce a 3D model of the complete
submarine site with a good precision in an absolute coordinate system.
To perform this survey an acoustic scanner 3D is used which can produce multiple
3D points with a same couple (x, y) coordinates, in opposite of standards bathymetric
echo sounder.
P. Drap et al.
14.2 Photogrammetry: Dense Map
To model the environment by photogrammetry in an unsupervised way it is first
necessary to automatically orient a set of unordered images. This orientation phase,
which is crucial in photogrammetry, as computer vision, has seen the past three
years a great boom. The problem was first solved in the case of ordered series of
photographs, for example, made a circle around an object and recently in the case
of photographs unordered (Barazzetti et al. 2010; Shunyi et al. 2007). Once all the
photographs are oriented several methods are proposed for producing a dense cloud
of 3D points to represent the area photographed.
Two major families of methods exist. Those that use solid models as the voxels
(Furukawa and Ponce 2010; Zeng Gang et al. 2005) are based on the discretization
of space into cells and the goal is to discriminate between full and empty cells to
define the boundary between them. The advantage of this method is to use lots of
photographs taken from arbitrary viewpoints. In contrast the delicacy of the final
model depends on the resolution of the voxel grid can be RAM consuming. On the
other hand methods using meshes could adapt their resolution to better reconstruct
the details of the scene (Morris and Kanade 2000).
Also the work of Furukawa and Ponce on the dense map generation (Agarwal et al.
2010; Furukawa and Ponce 2010) have also resulted in open source publications.
We use this work, merged with our own photogrammetric software in order to use
calibrated camera and some constraints on the bundle adjustment, for several months
and some examples are presented in this paper.
These developments were coupled with a software bundle adjustment of operating
on an unordered set of photographs are based on an implementation of SIFT on GPU
due to Changchang Wu, University of Washington (http://cs.unc.edu/ccwu/siftgpu)
and implantation of developments PhotoTourism (Agarwal et al. 2010; Snavely et al.
2010). The bundle adjustment used is based on the Sparse Bundle Adjustment of
Lourakis (Lourakis and Argyros 2009) and a version of the bundle adjustment of a
set of unordered photographs is available in open source: Bundler software (Snavely
et al. 2010).
On the other hand, since 2007 IGN (Institut Géographique National, in France) has
decided to publish in open source the APERO MICMAC software, dedicated to the
automatic orientation of an unordered set of photographs and the calculation of the
automatic mapping on a set of photographs oriented. (http://www.micmac.ign.fr)
(Pierrot-Deseilligny and Cléry 2011). Their approach is more rigorous from a
photogrammetric point of view and allows using calibrated camera.
14.3 Acoustic Survey
The acoustic survey is mainly useful to produce a 3D model of the complete
submarine site with a good precision in an absolute coordinate system.
To perform this survey an acoustic scanner 3D is used which can produce multiple
3D points with a same couple (x, y) coordinates, in opposite of standards bathymetric
echo sounder.