27,981 research outputs found
Single-shot layered reflectance separation using a polarized light field camera
We present a novel computational photography technique for single shot separation of diffuse/specular reflectance as well as novel angular domain separation of layered reflectance. Our solution consists of a two-way polarized light field (TPLF) camera which simultaneously captures two orthogonal states of polarization. A single photograph of a subject acquired with the TPLF camera under polarized illumination then enables standard separation of diffuse (depolarizing) and polarization preserving specular reflectance using light field sampling. We further demonstrate that the acquired data also enables novel angular separation of layered reflectance including separation of specular reflectance and single scattering in the polarization preserving component, and separation of shallow scattering from deep scattering in the depolarizing component. We apply our approach for efficient acquisition of facial reflectance including diffuse and specular normal maps, and novel separation of photometric normals into layered reflectance normals for layered facial renderings. We demonstrate our proposed single shot layered reflectance separation to be comparable to an existing multi-shot technique that relies on structured lighting while achieving separation results under a variety of illumination conditions
Exact Self-dual Soliton Solutions in a Gauged O(3) Sigma Model with Anomalous Magnetic Moment Interaction
It is shown that a gauged nonlinear sigma model with anomalous
magnetic moment interaction in dimensions is exactly integrable for
static, self-dual field configurations. The matter fields are exactly
equivalent to those of the usual ungauged nonlinear sigma model. These
static soliton solutions can be mapped into an Abelian purely magnetic vortex
solutions through a suitable reduction of the non-Abelian gauge group. A
relativistic Abelian model in dimensions is also presented where these
purely magnetic vortices can be realized.Comment: A discussion on case has been made. New references have been
added. To appear in Physics Letters B. RevTeX, 13 pages, no figur
Gauging by St\"uckelberg field-shifting symmetry
We embed second class constrained systems by a formalism that combines
concepts of the BFFT method and the unfixing gauge formalism. As a result, we
obtain a gauge-invariant system where the introduction of the Wess-Zumino (WZ)
field is essential. The initial phase-space variables are gauging with the
introduction of the WZ field, a procedure that resembles the St\"uckelberg
field- shifting formalism. In some cases, it is possible to eliminate the WZ
field and, therefore, obtain an invariant system written only as a function of
the original phase-space variables. We apply this formalism to important
physical models: the reduced-SU(2) Skyrme model and the two dimensional chiral
bosons field theory. In these systems, the gauge-invariant Hamiltonians are
derived in a very simple way when compared with other usual formalisms.Comment: revised version. To appear in Phys. Lett.
Distance, magnetic field and kinematics of a filamentary cloud LDN 1157
LDN 1157, is one of the several clouds situated in the cloud complex, LDN
1147/1158, represents a coma-shaped morphology with a well-collimated bipolar
outflow emanating from a Class 0 protostar, LDN 1157-mm. The main goals of this
work are (a) to map the inter-cloud magnetic field (ICMF) geometry of the
region surrounding LDN 1157 to investigate its relationship with the cloud
morphology, with the outflow direction and with the core magnetic field (CMF)
geometry inferred from the mm- and sub-mm polarization results from the
literature, and (b) to investigate the kinematic structure of the cloud. We
carried out R-band polarization observations of the stars projected on the
cloud to map the pc-scale magnetic field geometry and made spectroscopic
observations of the entire cloud in 12CO, C18O and N2H+ (J=1-0) lines to
investigate its kinematic structure. We obtained a distance of 3403 pc to
the LDN 1147/1158, complex based on the Gaia DR2 parallaxes and proper motion
values of the three YSOs associated with the complex. A single filament of
pc in length and pc in width is found to run all along the
coma-shaped cloud. Based on the relationships between the ICMF, CMF, filament
orientations, outflow direction, and the presence of an hour-glass morphology
of the magnetic field, it is likely that the magnetic field had played an
important role in the star formation process in LDN 1157. Combining the proper
motions of the YSOs and the radial velocity of LDN 1147/1158 and another
complex LDN 1172/1174 which is situated \dgr~east of it, we found that
both the complexes are moving collectively toward the Galactic plane. The
filamentary morphology of the east-west segment of LDN 1157 may have formed as
a result of mass lost by ablation due to the interaction of the moving cloud
with the ambient interstellar medium.Comment: 20 pages, Accepted in Astronomy & Astrophysics, Abstract has been
shortened due to word limit in arxi
- …