1,435 research outputs found
Adaptive image synthesis for compressive displays
Recent years have seen proposals for exciting new computational display technologies that are compressive in the sense that they generate high resolution images or light fields with relatively few display parameters. Image synthesis for these types of displays involves two major tasks: sampling and rendering high-dimensional target imagery, such as light fields or time-varying light fields, as well as optimizing the display parameters to provide a good approximation of the target content.
In this paper, we introduce an adaptive optimization framework for compressive displays that generates high quality images and light fields using only a fraction of the total plenoptic samples. We demonstrate the framework for a large set of display technologies, including several types of auto-stereoscopic displays, high dynamic range displays, and high-resolution displays. We achieve significant performance gains, and in some cases are able to process data that would be infeasible with existing methods.University of British Columbia (UBC Four Year Doctoral Fellowship)Natural Sciences and Engineering Research Council of Canada (Postdoctoral Fellowship)United States. Defense Advanced Research Projects Agency (DARPA SCENICC program)Alfred P. Sloan Foundation (Sloan Research Fellowship)United States. Defense Advanced Research Projects Agency (DARPA Young Faculty Award)University of British Columbia (Dolby Research Chair at UBC
On the Optimization of Deep Networks: Implicit Acceleration by Overparameterization
Conventional wisdom in deep learning states that increasing depth improves
expressiveness but complicates optimization. This paper suggests that,
sometimes, increasing depth can speed up optimization. The effect of depth on
optimization is decoupled from expressiveness by focusing on settings where
additional layers amount to overparameterization - linear neural networks, a
well-studied model. Theoretical analysis, as well as experiments, show that
here depth acts as a preconditioner which may accelerate convergence. Even on
simple convex problems such as linear regression with loss, ,
gradient descent can benefit from transitioning to a non-convex
overparameterized objective, more than it would from some common acceleration
schemes. We also prove that it is mathematically impossible to obtain the
acceleration effect of overparametrization via gradients of any regularizer.Comment: Published at the International Conference on Machine Learning (ICML)
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Dr.Bokeh: DiffeRentiable Occlusion-aware Bokeh Rendering
Bokeh is widely used in photography to draw attention to the subject while
effectively isolating distractions in the background. Computational methods
simulate bokeh effects without relying on a physical camera lens. However, in
the realm of digital bokeh synthesis, the two main challenges for bokeh
synthesis are color bleeding and partial occlusion at object boundaries. Our
primary goal is to overcome these two major challenges using physics principles
that define bokeh formation. To achieve this, we propose a novel and accurate
filtering-based bokeh rendering equation and a physically-based occlusion-aware
bokeh renderer, dubbed Dr.Bokeh, which addresses the aforementioned challenges
during the rendering stage without the need of post-processing or data-driven
approaches. Our rendering algorithm first preprocesses the input RGBD to obtain
a layered scene representation. Dr.Bokeh then takes the layered representation
and user-defined lens parameters to render photo-realistic lens blur. By
softening non-differentiable operations, we make Dr.Bokeh differentiable such
that it can be plugged into a machine-learning framework. We perform
quantitative and qualitative evaluations on synthetic and real-world images to
validate the effectiveness of the rendering quality and the differentiability
of our method. We show Dr.Bokeh not only outperforms state-of-the-art bokeh
rendering algorithms in terms of photo-realism but also improves the depth
quality from depth-from-defocus
Graph Spectral Image Processing
Recent advent of graph signal processing (GSP) has spurred intensive studies
of signals that live naturally on irregular data kernels described by graphs
(e.g., social networks, wireless sensor networks). Though a digital image
contains pixels that reside on a regularly sampled 2D grid, if one can design
an appropriate underlying graph connecting pixels with weights that reflect the
image structure, then one can interpret the image (or image patch) as a signal
on a graph, and apply GSP tools for processing and analysis of the signal in
graph spectral domain. In this article, we overview recent graph spectral
techniques in GSP specifically for image / video processing. The topics covered
include image compression, image restoration, image filtering and image
segmentation
PointHuman: Reconstructing Clothed Human from Point Cloud of Parametric Model
It is very difficult to accomplish the 3D reconstruction of the clothed human body from a single RGB image, because the 2D image lacks the representation information of the 3D human body, especially for the clothed human body. In order to solve this problem, we introduced a priority scheme of different body parts spatial information and proposed PointHuman network. PointHuman combines the spatial feature of the parametric model of the human body with the implicit functions without expressive restrictions. In PointHuman reconstruction framework, we use Point Transformer to extract the semantic spatial feature of the parametric model of the human body to regularize the implicit function of the neural network, which extends the generalization ability of the neural network to complex human poses and various styles of clothing. Moreover, considering the ambiguity of depth information, we estimate the depth of the parameterized model after point cloudization, and obtain an offset depth value. The offset depth value improves the consistency between the parameterized model and the neural implicit function, and accuracy of human reconstruction models. Finally, we optimize the restoration of the parametric model from a single image, and propose a depth perception method. This method further improves the estimation accuracy of the parametric model and finally improves the effectiveness of human reconstruction. Our method achieves competitive performance on the THuman dataset
Animatable 3D Gaussian: Fast and High-Quality Reconstruction of Multiple Human Avatars
Neural radiance fields are capable of reconstructing high-quality drivable
human avatars but are expensive to train and render. To reduce consumption, we
propose Animatable 3D Gaussian, which learns human avatars from input images
and poses. We extend 3D Gaussians to dynamic human scenes by modeling a set of
skinned 3D Gaussians and a corresponding skeleton in canonical space and
deforming 3D Gaussians to posed space according to the input poses. We
introduce hash-encoded shape and appearance to speed up training and propose
time-dependent ambient occlusion to achieve high-quality reconstructions in
scenes containing complex motions and dynamic shadows. On both novel view
synthesis and novel pose synthesis tasks, our method outperforms existing
methods in terms of training time, rendering speed, and reconstruction quality.
Our method can be easily extended to multi-human scenes and achieve comparable
novel view synthesis results on a scene with ten people in only 25 seconds of
training
Content-adaptive lenticular prints
Lenticular prints are a popular medium for producing automultiscopic glasses-free 3D images. The light field emitted by such prints has a fixed spatial and angular resolution. We increase both perceived angular and spatial resolution by modifying the lenslet array to better match the content of a given light field. Our optimization algorithm analyzes the input light field and computes an optimal lenslet size, shape, and arrangement that best matches the input light field given a set of output parameters. The resulting emitted light field shows higher detail and smoother motion parallax compared to fixed-size lens arrays. We demonstrate our technique using rendered simulations and by 3D printing lens arrays, and we validate our approach in simulation with a user study
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