53,749 research outputs found
Interactive inspection of complex multi-object industrial assemblies
The final publication is available at Springer via http://dx.doi.org/10.1016/j.cad.2016.06.005The use of virtual prototypes and digital models containing thousands of individual objects is commonplace in complex industrial applications like the cooperative design of huge ships. Designers are interested in selecting and editing specific sets of objects during the interactive inspection sessions. This is however not supported by standard visualization systems for huge models. In this paper we discuss in detail the concept of rendering front in multiresolution trees, their properties and the algorithms that construct the hierarchy and efficiently render it, applied to very complex CAD models, so that the model structure and the identities of objects are preserved. We also propose an algorithm for the interactive inspection of huge models which uses a rendering budget and supports selection of individual objects and sets of objects, displacement of the selected objects and real-time collision detection during these displacements. Our solution–based on the analysis of several existing view-dependent visualization schemes–uses a Hybrid Multiresolution Tree that mixes layers of exact geometry, simplified models and impostors, together with a time-critical, view-dependent algorithm and a Constrained Front. The algorithm has been successfully tested in real industrial environments; the models involved are presented and discussed in the paper.Peer ReviewedPostprint (author's final draft
Using image morphing for memory-efficient impostor rendering on GPU
Real-time rendering of large animated crowds consisting thousands of virtual humans is important for several applications including simulations, games and interactive walkthroughs; but cannot be performed using complex polygonal models at interactive frame rates. For that reason, several methods using large numbers of pre-computed image-based representations, which are called as impostors, have been proposed. These methods take the advantage of existing programmable graphics hardware to compensate the computational expense while maintaining the visual fidelity. Making the number of different virtual humans, which can be rendered in real-time, not restricted anymore by the required computational power but by the texture memory consumed for the variety and discretization of their animations. In this work, we proposed an alternative method that reduces the memory consumption by generating compelling intermediate textures using image-morphing techniques. In order to demonstrate the preserved perceptual quality of animations, where half of the key-frames were rendered using the proposed methodology, we have implemented the system using the graphical processing unit and obtained promising results at interactive frame rates
Loss-resilient Coding of Texture and Depth for Free-viewpoint Video Conferencing
Free-viewpoint video conferencing allows a participant to observe the remote
3D scene from any freely chosen viewpoint. An intermediate virtual viewpoint
image is commonly synthesized using two pairs of transmitted texture and depth
maps from two neighboring captured viewpoints via depth-image-based rendering
(DIBR). To maintain high quality of synthesized images, it is imperative to
contain the adverse effects of network packet losses that may arise during
texture and depth video transmission. Towards this end, we develop an
integrated approach that exploits the representation redundancy inherent in the
multiple streamed videos a voxel in the 3D scene visible to two captured views
is sampled and coded twice in the two views. In particular, at the receiver we
first develop an error concealment strategy that adaptively blends
corresponding pixels in the two captured views during DIBR, so that pixels from
the more reliable transmitted view are weighted more heavily. We then couple it
with a sender-side optimization of reference picture selection (RPS) during
real-time video coding, so that blocks containing samples of voxels that are
visible in both views are more error-resiliently coded in one view only, given
adaptive blending will erase errors in the other view. Further, synthesized
view distortion sensitivities to texture versus depth errors are analyzed, so
that relative importance of texture and depth code blocks can be computed for
system-wide RPS optimization. Experimental results show that the proposed
scheme can outperform the use of a traditional feedback channel by up to 0.82
dB on average at 8% packet loss rate, and by as much as 3 dB for particular
frames
SlicerAstro: a 3-D interactive visual analytics tool for HI data
SKA precursors are capable of detecting hundreds of galaxies in HI in a
single 12 hours pointing. In deeper surveys one will probe more easily faint HI
structures, typically located in the vicinity of galaxies, such as tails,
filaments, and extraplanar gas. The importance of interactive visualization has
proven to be fundamental for the exploration of such data as it helps users to
receive immediate feedback when manipulating the data. We have developed
SlicerAstro, a 3-D interactive viewer with new analysis capabilities, based on
traditional 2-D input/output hardware. These capabilities enhance the data
inspection, allowing faster analysis of complex sources than with traditional
tools. SlicerAstro is an open-source extension of 3DSlicer, a multi-platform
open source software package for visualization and medical image processing.
We demonstrate the capabilities of the current stable binary release of
SlicerAstro, which offers the following features: i) handling of FITS files and
astronomical coordinate systems; ii) coupled 2-D/3-D visualization; iii)
interactive filtering; iv) interactive 3-D masking; v) and interactive 3-D
modeling. In addition, SlicerAstro has been designed with a strong, stable and
modular C++ core, and its classes are also accessible via Python scripting,
allowing great flexibility for user-customized visualization and analysis
tasks.Comment: 18 pages, 11 figures, Accepted by Astronomy and Computing.
SlicerAstro link: https://github.com/Punzo/SlicerAstro/wiki#get-slicerastr
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