322,899 research outputs found
A comparison of various geometrical feature for damage assessment in VHR urban imagery
No full textUrban areas require scene interpretation tools with particular attention to geometric
features. Indeed, spatial analysis must be coupled to spectral characterization of ur-
ban materials if reliable and suitable land use or change detection maps needs to be
extracted. This is particularly true for Very High spatial resolution (VHR) imagery,
increasingly available both in the optical and the microwave regions of the electro-
magnetic spectrum.
In past work on spaceborne characterization of urban areas the most common geomet-
rical clues to scene interpretation in urban areas have always been segments, or edges.
They were used for instance for land use discrimination [1] or improved change detec-
tion techniques [2]. More complex geometrical features have been traditionally used
for aerial image interpretation, with a long experience due to the longer availability
of finer spatial resolution data. In the near future the availability of VHR data from
spaceborne platforms requires somehow a convergence of the two methodologies.
In this work, we try and analyze the possibility to exploit higher level geometrical
features, easily available in urban areas from VHR spaceborne imagery, to extract
information which not only improve change detection, but somehow allows a better
damage characterization than currently available. The methodology tries and exploits
the same clues to image interpretation that human interpreters usually look for in an
image. Examples are regular geometrical patterns (like rectangular shapes), pairs of
corresponding and parallel segments, corners with sufficient similarity. All of them
will be extracted and considered in the examples proposed in the final paper to improve
the possibility to detect or assess change due to destructive events in urban areas.
The algorithms developed in recent years by the group for geometrical scene analyysis [3] segment extraction [4] and junction detection [5] will be therefore revised
and jointly applied to improve the knowledge of pre-and post-event scenes in areas
affected by earthquakes, with particular stress on Quickbird data for the 2003 Bam
(Iran) event.
RE F E RE NCE S
1. J. Wang and P.J. Howarth: “Structural measures for linear feature pattern recog-
nition from satellite imagery,” Canadian Journal of Remote Sensing, vol. 17, pp.
294–303, 1991.
2. F. Dell’Acqua, P. Gamba, G. Lisini: “Change Detection of Multi-Temporal SAR
Data in Urban Areas Combining Feature-Based and Pixel-Based Techniques”,
IEEE Trans. on Geoscience and Remote Sensing, vol. 44, n.10, pp. 2820-2827,
Oct. 2006.
3. G. Lisini, F. Dell’Acqua, P. Gamba, W. Thompkinson: “Image interpreta-
tion through problem segmentation for very high resolution data”, Proc. of
IGARSS’05, Seoul (Korea), July 2005, pp. 534-5637.
4. F. Dell’Acqua, P. Gamba, G. Lisini: “Road map extraction by multiple detectors
in fine spatial resolution SAR data”, Canadian Journal of Remote Sensing, Vol.
29, n. 4, pp. 481-490, Aug. 2003.
5. F. Dell’Acqua, P. Gamba, G. Lisini, “Co-registration of multi-angle fine spatial
resolution SAR images”, IEEE Geoscience and Remote Sensing Letters, Vol. 1,
n. 4, pp. 237-241, Oct. 2004
Stability of flows associated to gradient vector fields and convergence of iterated transport maps
No full textIn this paper we address the problem of stability of flows
associated to a sequence of vector fields under minimal regularity requirements
on the limit vector field, that is supposed to be a gradient. We apply this
stability result to show the convergence of iterated compositions of optimal
transport maps arising in the implicit time discretization (with respect to the
Wasserstein distance) of nonlinear evolution equations of a diffusion type.
Finally, we use these convergence results to study the gradient flow of a
particular class of polyconvex functionals recently considered by Gangbo, Evans
ans Savin. We solve some open problems raised in their paper and obtain
existence and uniqueness of solutions under weaker regularity requirements and
with no upper bound on the jacobian determinant of the initial datum
On a class of modified Wasserstein distances induced by concave mobility functions defined on bounded intervals
No full textWe study a new class of distances between Radon measures similar to those studied in J. Dolbeault, B. Nazaret, G. Savaré, "A new class of transport distances between measures",Calc. Var. Partial Differential Equations, 34 (2009), pp. 193--231. These distances (more correctly pseudo-distances because can assume the value ) are defined generalizing the dynamical formulation of the Wasserstein distance by means of a concave mobility function. We are mainly interested in the physical interesting case (not considered in D.-N.-S.) of a concave mobility function defined in a bounded interval. We state the basic properties of the space of measures endowed with this pseudo-distance. Finally, we study in detail two cases: the set of measures defined in with finite moments and the set of measuresdefined in a bounded convex set. In the two cases we give sufficient conditions for the convergence of sequences with respect to the distance and we prove a property of boundedness
Gradient flows for non-smooth interaction potentials
No full text26.01.15 KB. OK to add accepted version to spiral, subject to 12 months embarg
Mean-field optimal control as Gamma-limit of finite agent controls
No full textThis paper focuses on the role of a government of a large population of interacting agents as a meanfield optimal control problem derived from deterministic finite agent dynamics. The control problems are constrained by a Partial Differential Equation of continuity-type without diffusion, governing the dynamics of the probability distribution of the agent population. We derive existence of optimal controls in a measure-theoretical setting as natural limits of finite agent optimal controls without any assumption on the regularity of control competitors. In particular, we prove the consistency of mean-field optimal controls with corresponding underlying finite agent ones. The results follow from a Γ -convergence argument constructed over the mean-field limit, which stems from leveraging the superposition principle
"Theoretical study of the photoelectron spectrum of Cesium" in: “Fundamental Processes in Atomic Collision Physics
No full text
Lagrangian, Eulerian and Kantorovich formulations of multi-agent optimal control problems: Equivalence and Gamma-convergence
No full textThis paper is devoted to the study of multi-agent deterministic optimal control problems. We initially provide a thorough analysis of the Lagrangian, Eulerian and Kantorovich formulations of the problems, as well as of their relaxations. Then we exhibit some equivalence results among the various representations and compare the respective value functions. To do it, we combine techniques and ideas from optimal transportation, control theory, Young measures and evolution equations in Banach spaces. We further exploit the connections among Lagrangian and Eulerian descriptions to derive consistency results as the number of particles/agents tends to infinity. To that purpose we prove an empirical version of the Superposition Principle and obtain suitable Gamma-convergence results for the controlled systems
Adrenarche in patients with central precocious puberty: Influence on growth parameters before and during GnRH-Analog therapy
No full textObjective: the aims of this study were to evaluate the relationship between
adrenarche and central precocious puberty (CPP) and the influence of the
adrenarche upon skeletal maturation and growth parameters of patients with
CPP during GnRH-A therapy.
Patients and methods: 40 patients (37 F, 3M) with CPP were studied before
and during 2-4 years of GnRH-A therapy. Mean age at onset of CPP and at
the start of GnRH-A therapy were 6.35±1.78 yrs and 7.7±1.6 yrs, respectively.
The plasma DHEA-S levels at a concentration > 0.60 mcg/ml were used as a
hormonal marker of adrenarche.
Results: Before GnRH-A therapy 30 out of 40 patients aged 7.33±1.7 yrs had
a preadrenarcheal DHEA-S levels that were similar to those of prepubertal
age-matched controls, the remaining 10 patients older than 7 yrs (8.27±0.84
yrs) showed adrenarcheal DHEA-S levels that were similar to those of normal
pubertal children. Before therapy the adrenarcheal children didn’t show significant
differences in growth parameters and bone age (BA) compared with
preadrenarcheal patients, in the former the BMI SDS tended to be higher than
in the latter but not significantly (1.92±1.84 vs 1.35±1.81). During gonadal
suppression, the improvement in predicted adult height and in CA /BA ratio
induced by GnRH-A therapy was not significantly different in adrenarcheal
and preadrenarcheal patients.
Conclusion: The results of this study show that adrenarche was present only
in patients with onset of CPP after 7 years of age. This finding may suggest
that the onset of CPP was independent of activation of adrenal androgens in
young patients. The adrenarcheal children didn‘t show growth parameters and
bone age maturation different from those without adrenarche. Moreover, the
increased adrenal DHEA-S production at the diagnosis of CPP didn‘t restrain
the beneficial effects of GnRH-A therapy on bone age and predicted adult
height of our CPP patients
- …
