10,578 research outputs found
Symbol detection in online handwritten graphics using Faster R-CNN
Symbol detection techniques in online handwritten graphics (e.g. diagrams and
mathematical expressions) consist of methods specifically designed for a single
graphic type. In this work, we evaluate the Faster R-CNN object detection
algorithm as a general method for detection of symbols in handwritten graphics.
We evaluate different configurations of the Faster R-CNN method, and point out
issues relative to the handwritten nature of the data. Considering the online
recognition context, we evaluate efficiency and accuracy trade-offs of using
Deep Neural Networks of different complexities as feature extractors. We
evaluate the method on publicly available flowchart and mathematical expression
(CROHME-2016) datasets. Results show that Faster R-CNN can be effectively used
on both datasets, enabling the possibility of developing general methods for
symbol detection, and furthermore, general graphic understanding methods that
could be built on top of the algorithm.Comment: Submitted to DAS-201
From Rank Estimation to Rank Approximation: Rank Residual Constraint for Image Restoration
In this paper, we propose a novel approach to the rank minimization problem,
termed rank residual constraint (RRC) model. Different from existing low-rank
based approaches, such as the well-known nuclear norm minimization (NNM) and
the weighted nuclear norm minimization (WNNM), which estimate the underlying
low-rank matrix directly from the corrupted observations, we progressively
approximate the underlying low-rank matrix via minimizing the rank residual.
Through integrating the image nonlocal self-similarity (NSS) prior with the
proposed RRC model, we apply it to image restoration tasks, including image
denoising and image compression artifacts reduction. Towards this end, we first
obtain a good reference of the original image groups by using the image NSS
prior, and then the rank residual of the image groups between this reference
and the degraded image is minimized to achieve a better estimate to the desired
image. In this manner, both the reference and the estimated image are updated
gradually and jointly in each iteration. Based on the group-based sparse
representation model, we further provide a theoretical analysis on the
feasibility of the proposed RRC model. Experimental results demonstrate that
the proposed RRC model outperforms many state-of-the-art schemes in both the
objective and perceptual quality
Earthquake scenarios and seismic input for cultural heritage: applications to the cities of Rome and Florence
For historical buildings and monuments, i.e. when considering time intervals
of about a million year (we do not want to loose cultural heritage), the
applicability of standard estimates of seismic hazard is really questionable. A
viable alternative is represented by the use of the scenario earthquakes,
characterized at least in terms of magnitude, distance and faulting style, and
by the treatment of complex source processes. Scenario-based seismic hazard
maps are purely based on geophysical and seismotectonic features of a region
and take into account the occurrence frequency of earthquakes only for their
classification into exceptional (catastrophic), rare (disastrous), sporadic
(very strong), occasional (strong) and frequent. Therefore they may provide an
upper bound for the ground motion levels to be expected for most regions of the
world, more appropriate than probabilities of exceedance in view of the long
time scales required for the protection of historical buildings. The
neo-deterministic approach naturally supplies realistic time series of ground
motion, which represent also reliable estimates of ground displacement readily
applicable to seismic isolation techniques, useful to preserve historical
monuments and relevant man made structures. This methodology has been
successfully applied to many urban areas worldwide for the purpose of seismic
microzoning, to strategic buildings, lifelines and cultural heritage sites; we
will discuss its application to the cities of Rome and Florence
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