126 research outputs found
Computing the Component-Labeling and the Adjacency Tree of a Binary Digital Image in Near Logarithmic-Time
Connected component labeling (CCL) of binary images is
one of the fundamental operations in real time applications. The adjacency
tree (AdjT) of the connected components offers a region-based
representation where each node represents a region which is surrounded
by another region of the opposite color. In this paper, a fully parallel
algorithm for computing the CCL and AdjT of a binary digital image
is described and implemented, without the need of using any geometric
information. The time complexity order for an image of m × n pixels
under the assumption that a processing element exists for each pixel is
near O(log(m+ n)). Results for a multicore processor show a very good
scalability until the so-called memory bandwidth bottleneck is reached.
The inherent parallelism of our approach points to the direction that
even better results will be obtained in other less classical computing
architectures.Ministerio de Economía y Competitividad MTM2016-81030-PMinisterio de Economía y Competitividad TEC2012-37868-C04-0
Generating Second Order (Co)homological Information within AT-Model Context
In this paper we design a new family of relations between
(co)homology classes, working with coefficients in a field and starting
from an AT-model (Algebraic Topological Model) AT(C) of a finite cell
complex C These relations are induced by elementary relations of type
“to be in the (co)boundary of” between cells. This high-order connectivity
information is embedded into a graph-based representation model,
called Second Order AT-Region-Incidence Graph (or AT-RIG) of C. This
graph, having as nodes the different homology classes of C, is in turn,
computed from two generalized abstract cell complexes, called primal
and dual AT-segmentations of C. The respective cells of these two complexes
are connected regions (set of cells) of the original cell complex C,
which are specified by the integral operator of AT(C). In this work in
progress, we successfully use this model (a) in experiments for discriminating
topologically different 3D digital objects, having the same Euler
characteristic and (b) in designing a parallel algorithm for computing
potentially significant (co)homological information of 3D digital objects.Ministerio de Economía y Competitividad MTM2016-81030-PMinisterio de Economía y Competitividad TEC2012-37868-C04-0
Homological Region Adjacency Tree for a 3D Binary Digital Image via HSF Model
Given a 3D binary digital image I, we define and compute
an edge-weighted tree, called Homological Region Tree (or Hom-Tree,
for short). It coincides, as unweighted graph, with the classical Region
Adjacency Tree of black 6-connected components (CCs) and white 26-
connected components of I. In addition, we define the weight of an edge
(R, S) as the number of tunnels that the CCs R and S “share”. The
Hom-Tree structure is still an isotopic invariant of I. Thus, it provides
information about how the different homology groups interact between
them, while preserving the duality of black and white CCs.
An experimentation with a set of synthetic images showing different
shapes and different complexity of connected component nesting is performed
for numerically validating the method.Ministerio de Economía y Competitividad MTM2016-81030-
A parallel Homological Spanning Forest framework for 2D topological image analysis
In [14], a topologically consistent framework to support parallel topological analysis and recognition for2 D digital objects was introduced. Based on this theoretical work, we focus on the problem of findingefficient algorithmic solutions for topological interrogation of a 2 D digital object of interest D of a pre- segmented digital image I , using 4-adjacency between pixels of D . In order to maximize the degree ofparallelization of the topological processes, we use as many elementary unit processing as pixels theimage I has. The mathematical model underlying this framework is an appropriate extension of the clas- sical concept of abstract cell complex: a primal–dual abstract cell complex (pACC for short). This versatiledata structure encompasses the notion of Homological Spanning Forest fostered in [14,15]. Starting froma symmetric pACC associated with I , the modus operandi is to construct via combinatorial operationsanother asymmetric one presenting the maximal number of non-null primal elementary interactions be- tween the cells of D . The fundamental topological tools have been transformed so as to promote anefficient parallel implementation in any parallel-oriented architecture (GPUs, multi-threaded computers,SIMD kernels and so on). A software prototype modeling such a parallel framework is built.Ministerio de Educación y Ciencia TEC2012-37868-C04-02/0
Toward Parallel Computation of Dense Homotopy Skeletons for nD Digital Objects
An appropriate generalization of the classical notion of
abstract cell complex, called primal-dual abstract cell complex (pACC
for short) is the combinatorial notion used here for modeling and analyzing
the topology of nD digital objects and images. Let D ⊂ I be a set of
n-xels (ROI) and I be a n-dimensional digital image.We design a theoretical
parallel algorithm for constructing a topologically meaningful asymmetric
pACC HSF(D), called Homological Spanning Forest of D (HSF
of D, for short) starting from a canonical symmetric pACC associated
to I and based on the application of elementary homotopy operations
to activate the pACC processing units. From this HSF-graph representation
of D, it is possible to derive complete homology and homotopy
information of it. The preprocessing procedure of computing HSF(I) is
thoroughly discussed. In this way, a significant advance in understanding
how the efficient HSF framework for parallel topological computation of
2D digital images developed in [2] can be generalized to higher dimension
is made.Ministerio de Economía y Competitividad TEC2016-77785-PMinisterio de Economía y Competitividad MTM2016-81030-
Labeling Color 2D Digital Images in Theoretical Near Logarithmic Time
A design of a parallel algorithm for labeling color flat zones
(precisely, 4-connected components) of a gray-level or color 2D digital
image is given. The technique is based in the construction of a particular
Homological Spanning Forest (HSF) structure for encoding topological
information of any image.HSFis a pair of rooted trees connecting the image
elements at inter-pixel level without redundancy. In order to achieve a correct
color zone labeling, our proposal here is to correctly building a sub-
HSF structure for each image connected component, modifying an initial
HSF of the whole image. For validating the correctness of our algorithm,
an implementation in OCTAVE/MATLAB is written and its results are
checked. Several kinds of images are tested to compute the number of iterations
in which the theoretical computing time differs from the logarithm
of the width plus the height of an image. Finally, real images are to be computed
faster than random images using our approach.Ministerio de Economía y Competitividad TEC2016-77785-PMinisterio de Economía y Competitividad MTM2016-81030-
A Parallel Implementation for Computing the Region-Adjacency-Tree of a Segmentation of a 2D Digital Image
A design and implementation of a parallel algorithm for computing
the Region-Adjacency Tree of a given segmentation of a 2D digital
image is given. The technique is based on a suitable distributed use of
the algorithm for computing a Homological Spanning Forest (HSF) structure
for each connected region of the segmentation and a classical geometric
algorithm for determining inclusion between regions. The results
show that this technique scales very well when executed in a multicore
processor.Ministerio de Ciencia e Innovación TEC2012-37868-C04-02Universidad de Sevilla 2014/75
An eLearning Standard Approach for Supporting PBL in Computer Engineering
Problem-based learning (PBL) has proved to be a highly successful pedagogical model in many fields, although it is not that common in computer engineering. PBL goes beyond the typical teaching methodology by promoting student interaction. This paper presents a PBL trial applied to a course in a computer engineering degree at the University of Seville, Spain. To promote the reusability and interoperability of the PBL trial, a design-driven approach was used, based on the Internet protocol Multimedia Subsystems (IMS) Learning Design (LD) standard. This paper presents the outcomes of using this method to innovate teaching practices in a blended learning environment. Design and implementation results, as well as users' opinions, are presented and analyzed.Ministerio de Educación y Ciencia TIN2006-15617-C03-03Junta de Andalucía P06-TIC-0229
Using virtual potential fields for electric wheelchair guidance
TetraNauta is an electric wheelchair guidance system intended for people with heavy motion impairments (such as persons with tetraplegia). It is specially useful when impairments also affect wheelchair steering as it is able to automatically guide wheelchairs between different points in a known environment (a hospital, a school, etc), conditioned with track marks painted on the floor. It also provides a semiautomatic navigation mode, where control is shared between user and navigation system. It is intended for learning wheelchair manipulation and as an aid in places where navigation is difficult or dangerous (i.e. for crossing narrow corridors)
Robotics software frameworks for multi-agent robotic systems development
Robotics is an area of research in which the paradigm of Multi-Agent Systems (MAS) can prove to be highly
useful. Multi-Agent Systems come in the form of cooperative robots in a team, sensor networks based on
mobile robots, and robots in Intelligent Environments, to name but a few. However, the development
of Multi-Agent Robotic Systems (MARS) still presents major challenges. Over the past decade, a high
number of Robotics Software Frameworks (RSFs) have appeared which propose some solutions to the
most recurrent problems in robotics. Some of these frameworks, such as ROS, YARP, OROCOS, ORCA,
Open-RTM, and Open-RDK, possess certain characteristics and provide the basic infrastructure necessary
for the development of MARS. The contribution of this work is the identification of such characteristics
as well as the analysis of these frameworks in comparison with the general-purpose Multi-Agent System
Frameworks (MASFs), such as JADE and Mobile-C.Ministerio de Ciencia e Innovación TEC2009-10639-C04-02Junta de Andalucía P06-TIC-2298Junta de Andalucía P08-TIC-0386
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