22,919 research outputs found
3DPortraitGAN: Learning One-Quarter Headshot 3D GANs from a Single-View Portrait Dataset with Diverse Body Poses
3D-aware face generators are typically trained on 2D real-life face image
datasets that primarily consist of near-frontal face data, and as such, they
are unable to construct one-quarter headshot 3D portraits with complete head,
neck, and shoulder geometry. Two reasons account for this issue: First,
existing facial recognition methods struggle with extracting facial data
captured from large camera angles or back views. Second, it is challenging to
learn a distribution of 3D portraits covering the one-quarter headshot region
from single-view data due to significant geometric deformation caused by
diverse body poses. To this end, we first create the dataset
360{\deg}-Portrait-HQ (360{\deg}PHQ for short) which consists of high-quality
single-view real portraits annotated with a variety of camera parameters (the
yaw angles span the entire 360{\deg} range) and body poses. We then propose
3DPortraitGAN, the first 3D-aware one-quarter headshot portrait generator that
learns a canonical 3D avatar distribution from the 360{\deg}PHQ dataset with
body pose self-learning. Our model can generate view-consistent portrait images
from all camera angles with a canonical one-quarter headshot 3D representation.
Our experiments show that the proposed framework can accurately predict
portrait body poses and generate view-consistent, realistic portrait images
with complete geometry from all camera angles
Portraits of Julius Caesar: a proposal for 3D analysis
Here I suggest the use of a 3D scanning and rendering to create some virtual
copies of ancient artifacts to study and compare them. In particular, this
approach could be interesting for some roman marble busts, two of which are
portraits of Julius Caesar, and the third is a realistic portrait of a man
recently found at Arles, France. The comparison of some images indicates that a
three-dimensional visualization is necessary.Comment: Key-words: Image processing, 3D Scanner, 3D visualization, Ancient
Rome, Julius Caesa
Theory on the Dynamics of Oscillatory Loops in the Transcription Factor Networks
We develop a detailed theoretical framework for various types of
transcription factor gene oscillators. We further demonstrate that one can
build genetic-oscillators which are tunable and robust against perturbations in
the critical control parameters by coupling two or more independent
Goodwin-Griffith oscillators through either -OR- or -AND- type logic. Most of
the coupled oscillators constructed in the literature so far seem to be of -OR-
type. When there are transient perturbations in one of the -OR- type
coupled-oscillators, then the overall period of the system remains constant
(period-buffering) whereas in case of -AND- type coupling the overall period of
the system moves towards the perturbed oscillator. Though there is a
period-buffering, the amplitudes of oscillators coupled through -OR- type logic
are more sensitive to perturbations in the parameters associated with the
promoter state dynamics than -AND- type. Further analysis shows that the period
of -AND- type coupled dual-feedback oscillators can be tuned without conceding
on the amplitudes. Using these results we derive the basic design principles
governing the robust and tunable synthetic gene oscillators without
compromising on their amplitudes.Comment: 37 pages, 13 figures, 2 table
Cosmology With Negative Potentials
We investigate cosmological evolution in models where the effective potential
V(\phi) may become negative for some values of the field \phi. Phase portraits
of such theories in space of variables (\phi,\dot\phi,H) have several
qualitatively new features as compared with phase portraits in the theories
with V(\phi) > 0. Cosmological evolution in models with potentials with a
"stable" minimum at V(\phi)<0 is similar in some respects to the evolution in
models with potentials unbounded from below. Instead of reaching an AdS regime
dominated by the negative vacuum energy, the universe reaches a turning point
where its energy density vanishes, and then it contracts to a singularity with
properties that are practically independent of V(\phi). We apply our methods to
investigation of the recently proposed cyclic universe scenario. We show that
in addition to the singularity problem there are other problems that need to be
resolved in order to realize a cyclic regime in this scenario. We propose
several modifications of this scenario and conclude that the best way to
improve it is to add a usual stage of inflation after the singularity and use
that inflationary stage to generate perturbations in the standard way.Comment: 51 page, 20 figure
Text-based Editing of Talking-head Video
Editing talking-head video to change the speech content or to remove filler words is challenging. We propose a novel method to edit talking-head video based on its transcript to produce a realistic output video in which the dialogue of the speaker has been modified, while maintaining a seamless audio-visual flow (i.e. no jump cuts). Our method automatically annotates an input talking-head video with phonemes, visemes, 3D face pose and geometry, reflectance, expression and scene illumination per frame. To edit a video, the user has to only edit the transcript, and an optimization strategy then chooses segments of the input corpus as base material. The annotated parameters corresponding to the selected segments are seamlessly stitched together and used to produce an intermediate video representation in which the lower half of the face is rendered with a parametric face model. Finally, a recurrent video generation network transforms this representation to a photorealistic video that matches the edited transcript. We demonstrate a large variety of edits, such as the addition, removal, and alteration of words, as well as convincing language translation and full sentence synthesis
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