- multi-image photogrammetry is becoming the most accurate and cost effective method of documentation in underwater archeology
- a 3d point cloud is difficult to use directly for analysis and comparison of object shapes
- volumetric shape models can address some of this difficulties
- superquadric volumetric shape models can be automatically recovered from a point cloud
- superquadric models offer an abstraction level suitable for reasoning about a scene
- stereo and photogrammetry in 1960s George Bass
- 3D available only after the field work was already finished
- documentation performed mostly manually - imperfections
- 3D points with textures excellent for visualization, not for further analysis
- rigid grid of squares 2m x 2m, 34 diving hours
- 900 photos, 1h
- DSRL Nikon 300
- Roman shipwreck with sarcophagi cargo 2nd century
- Sutivan, Brač, Croatia
- 30 tons
- largest in west cost Adriatic (besides another a bit norhter)
- first discovered by PIK Mornar, 2008
- research 2010-2012
- photo Rok Kovačič, 3D Gregor berginc Xlab, 3dimenzija, PHOV
- 40m2, 35m depth
- 24 semi-manifactured stone blocks, 2 sarcophagi with lids, circular stone column, oil jar
- ship had to be 20-22 meters
- antique, wood artefacts dated to 2nd century
- Aegan basin and Asia Minor
- a1, a2, a3 - distances on axies
- e1, e2 - shape
- 6 additional for translation and rotation
- recovery and segmentation at the same time, procedure
- 3d points covered with small sq seeds
- each seed fitted to corresponding 3d set
- the sq models can the next iteration expand so that 3D points that are in the vicinity of the corresponding model and are compatible with the shape of the superquadric can be integrated into the model
- when superquadric models expand as allowed by the 3D points, they start to overlap
- a selection procedure is performed using the criterion of minimum description length so that in each iteration fewer superquadric models remain
- after a few iterations only as many superquadric models remain as are necessary by the parts structure in the 3D data
- recovered 3, 5, 6, 8, 9, 10, 11 and 13
- average error, error std deviation
- compared to manual point-to-point measurements
- multi-image photogrammetry will prevail
- sq offer a level of abstraction, important when you have to deal with that much data
- simple parametrization: very few parameters
- could be used for shape indexing and and searching for similar objects
- sq recover average shape of model