54 research outputs found
Painterly rendering techniques: A state-of-the-art review of current approaches
In this publication we will look at the different methods presented over the past few decades which attempt to recreate digital paintings. While previous surveys concentrate on the broader subject of non-photorealistic rendering, the focus of this paper is firmly placed on painterly rendering techniques. We compare different methods used to produce different output painting styles such as abstract, colour pencil, watercolour, oriental, oil and pastel. Whereas some methods demand a high level of interaction using a skilled artist, others require simple parameters provided by a user with little or no artistic experience. Many methods attempt to provide more automation with the use of varying forms of reference data. This reference data can range from still photographs, video, 3D polygonal meshes or even 3D point clouds. The techniques presented here endeavour to provide tools and styles that are not traditionally available to an artist. Copyright © 2012 John Wiley & Sons, Ltd
Animated rendering of cardiac model simulations
Heart disease has been the leading cause of death both in the world and the United States
in the past decade. Computational cardiac modeling and simulation, especially patient-specific
cardiac modeling has been recognized as one of the best ways to improve diagnosis of heart
disease by providing insights in individual disease characteristics that cannot be obtained by
other means. However presenting the results of cardiac simulations to cardiologists in an
interactive manner can considerably improve the utility of cardiac models in understanding
the heart function. In this work, we have developed virtual reality and animated volume
rendering techniques to render the results of cardiac simulations. We have developed a GPU
accelerated algorithm that produces time varying voxelized representation of the quantities of
interest in a cardiac model, which can then be interactively rendered in real time. We voxelize
the different time frames of the analysis model and transfer the time-varying data to the GPU
memory using a flat data structure. This technique allows us to visualize and interact with
animation in real time. As a proof-of-concept, we test our method on interactively rendering
the simulation results of cardiac biomechanics simulations. We also present the timing results
on post-processing and rendering two different cardiac IGA at different resolutions. We achieve
an interactive frame rate of over 50 fps for all test cases
Transfer of albedo and local depth variation to photo-textures
Acquisition of displacement and albedo maps for full building façades is a difficult problem and traditionally achieved through a labor intensive artistic process. In this paper, we present a material appearance transfer method, Transfer by Analogy, designed to infer surface detail and diffuse reflectance for textured surfaces like the present in building façades. We begin by acquiring small exemplars (displacement and albedo maps), in accessible areas, where capture conditions can be controlled. We then transfer these properties to a complete phototexture constructed from reference images and captured under diffuse daylight illumination. Our approach allows super-resolution inference of albedo and displacement from information in the photo-texture. When transferring appearance from multiple exemplars to façades containing multiple materials, our approach also sidesteps the need for segmentation. We show how we use these methods to create relightable models with a high degree of texture detail, reproducing the visually rich self-shadowing effects that would normally be difficult to capture using just simple consumer equipment. Copyright © 2012 by the Association for Computing Machinery, Inc
Compact union of disjoint boxes: An efficient decomposition model for binary volumes
This paper presents in detail the CompactUnion of Disjoint Boxes (CUDB), a decomposition modelfor binary volumes that has been recently but brieflyintroduced. This model is an improved version of aprevious model called Ordered Union of Disjoint Boxes(OUDB). We show here, several desirable features thatthis model has versus OUDB, such as less unitary basicelements (boxes) and thus, a better efficiency in someneighborhood operations. We present algorithms forconversion to and from other models, and for basiccomputations as area (2D) or volume (3D). We alsopresent an efficient algorithm for connected-componentlabeling (CCL) that does not follow the classical two-passstrategy. Finally we present an algorithm for collision (oradjacency) detection in static environments. We test theefficiency of CUDB versus existing models with severaldatasets.Peer ReviewedPostprint (published version
Body Knowledge and Uncertainty Modeling for Monocular 3D Human Body Reconstruction
While 3D body reconstruction methods have made remarkable progress recently,
it remains difficult to acquire the sufficiently accurate and numerous 3D
supervisions required for training. In this paper, we propose \textbf{KNOWN}, a
framework that effectively utilizes body \textbf{KNOW}ledge and
u\textbf{N}certainty modeling to compensate for insufficient 3D supervisions.
KNOWN exploits a comprehensive set of generic body constraints derived from
well-established body knowledge. These generic constraints precisely and
explicitly characterize the reconstruction plausibility and enable 3D
reconstruction models to be trained without any 3D data. Moreover, existing
methods typically use images from multiple datasets during training, which can
result in data noise (\textit{e.g.}, inconsistent joint annotation) and data
imbalance (\textit{e.g.}, minority images representing unusual poses or
captured from challenging camera views). KNOWN solves these problems through a
novel probabilistic framework that models both aleatoric and epistemic
uncertainty. Aleatoric uncertainty is encoded in a robust Negative
Log-Likelihood (NLL) training loss, while epistemic uncertainty is used to
guide model refinement. Experiments demonstrate that KNOWN's body
reconstruction outperforms prior weakly-supervised approaches, particularly on
the challenging minority images.Comment: ICCV 202
Eulerian on Lagrangian Cloth Simulation
This thesis introduces a novel Eulerian-on-Lagrangian (EoL) approach for simulating cloth. This approach allows for the simulation of traditionally difficult cloth scenarios, such as draping and sliding cloth over sharp features like the edge of a table. A traditional Lagrangian approach models a cloth as a series of connected nodes. These nodes are free to move in 3d space, but have difficulty with sliding over hard edges. The cloth cannot always bend smoothly around these edges, as motion can only occur at existing nodes. An EoL approach adds additional flexibility to a Lagrangian approach by constructing special Eulerian on Lagrangian nodes (EoL Nodes), where cloth material can pass through a fixed point. On contact with the edge of a box, EoL nodes are introduced directly on the edge. These nodes allow the cloth to bend exactly at the edge, and pass smoothly over the area while sliding. Using this ‘Eulerian-on-Lagrangian’ discretization, a set of rules for introducing and constraining EoL Nodes, and an adaptive remesher, This simulator allows cloth to move in a sliding motion over sharp edges. The current implementation is limited to cloth collision with static boxes, but the method presented can be expanded to include contact with more complicated meshes and dynamic rigid bodies
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