Title:
An interactive local flattening
operator to support digital investigations on artwork surfaces
Authors: N. Pietroni, M. Corsini, P. Cignoni, R.Scopigno
Publication venue: IEEE Trans. on Visualization and Computer Graphics
(Proc. IEEE Visualization 2011)
ABSTRACT
Analyzing either high-frequency shape detail or any other
2D fields (scalar or vector) embedded over a 3D geometry is a complex
task, since
detaching
the detail from the overall shape can be tricky. An
alternative approach is to move to the 2D space, resolving shape reasoning
to
easier image processing techniques. In this paper we propose a novel
framework for the analysis of 2D information distributed
over
3D geometry, based on a locally smooth parametrization technique
that allows us to treat local 3D data in terms of image
content.
The proposed approach has been implemented as a sketch-based
system that allows to design with a few gestures a
set of (possibly overlapping) parameterizations of rectangular portions
of the surface. We demonstrate that, due to the locality of
the
parametrization, the distortion is under an acceptable threshold,
while discontinuities can be avoided since the parametrized geometry
is
always homeomorphic to a disk. We show the effectiveness of the
proposed technique to solve specific Cultural Heritage (CH)
tasks:
the analysis of chisel marks over the surface of a unfinished
sculpture and the local comparison of multiple photographs mapped
over
the surface of an artwork. We believe that our framework and the
corresponding tool are the first steps toward a computer-based
shape
reasoning system, able to support CH scholars with a medium they
are more used to.
Chisel marks
characterization Our local flattening
operator may been conceived as a new digital
tool to make measurements and comparisons in a radically new way
over the digital representation of the artworks
Some images presented in the paper
Pietà di Palestrina
one pixel = 0.25 mm (right click to download full resolution
version)
one
pixel
= 0.25 mm (right click
to download full resolution version)
San Matteo
one pixel = 0.25 mm (right click to download full resolution
version)
one
pixel
= 0.25 mm (right click
to download full resolution version)
Measurable
evaluation
of the restoration results A second example of the
capabilities of the proposed framework is
the visual comparison of the appearance of an artwork before and after
some critical events like a restoration
David
Correlate
marks with curvature The proposed framework
allows to compare in a common parametric
space different shape characteristics, possibly also at different level
of
scale. In this sense, another application is to compare the main surface
curvature direction, evaluated on a low resolution and smoothed
representation,
with the orientation of the residual traces.