| 1. |
- Wesslén, Daniel, et al.
(författare)
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Real-time visualization of animated trees
- 2005
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Ingår i: The Visual Computer. - : Springer Science and Business Media LLC. - 0178-2789 .- 1432-2315 .- 1432-8726. ; 21:6, s. 397-405
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Tidskriftsartikel (refereegranskat)abstract
- Realistic visualization of plants and trees has recently received increased interest in various fields of applications. Limited computational power and the extreme complexity of botanical structures have called for tradeoffs between interactivity and realism. In this paper we present methods for the creation and real-time visualization of animated trees. In contrast to other previous research, our work is geared toward near-field visualization of highly detailed areas of forestry scenes with animation. We describe methods for rendering and shading of trees by utilizing the programmable hardware of consumer-grade graphics cards. We then describe a straightforward technique for animation of swaying stems and fluttering foliage that can be executed locally on a graphics processor. Our results show that highly detailed tree structures can be visualized at real-time frame rates and that animation of plant structures can be accomplished without sacrificing performance.
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| 2. |
- Andersson, Magnus, et al.
(författare)
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Efficient multi-view ray tracing using edge detection and shader reuse
- 2011
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Ingår i: The Visual Computer. - : Springer Science and Business Media LLC. - 0178-2789 .- 1432-2315. ; 27:6-8, s. 665-676
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Konferensbidrag (refereegranskat)abstract
- Stereoscopic rendering and 3D stereo displays are quickly becoming mainstream. The natural extension is autostereoscopic multi-view displays, which by the use of parallax barriers or lenticular lenses, can accommodate many simultaneous viewers without the need for active or passive glasses. As these displays, for the foreseeable future, will support only a rather limited number of views, there is a need for high-quality interperspective antialiasing. We present a specialized algorithm for efficient multi-view image generation from a camera line using ray tracing, which builds on previous methods for multi-dimensional adaptive sampling and reconstruction of light elds. We introduce multi-view silhouette edges to detect sharp geometrical discontinuities in the radiance function. These are used to significantly improve the quality of the reconstruction. In addition, we exploit shader coherence by computing analytical visibility between shading points and the camera line, and by sharing shading computations over the camera line.
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| 3. |
- Assarsson, Ulf, 1972, et al.
(författare)
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Occlusion Culling and Z-fail for Soft Shadow Volume Algorithms
- 2004
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Ingår i: Visual Computer. - : Springer Science and Business Media LLC. - 0178-2789 .- 1432-2315. ; 20:8-9, s. 601-612
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a significant improvement of our previously proposed soft shadow volume algorithm for simulating soft shadows. By restructuring the algorithm, we can considerably simplify the computations, introduce efficient occlusion culling with speedups of 3-4 times, thus approaching real-time performance. We can also generalize the algorithm to produce correct shadows even when the eye is inside a shadowed region (using z-fail). We present and evaluate a three pass implementation of the restructured algorithm for near real-time rendering of soft shadows on a computer with a commodity graphics accelerator. However, preferably the rendering of the wedges should be implemented in hardware, and for this we suggest and evaluate a single pass algorithm.
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| 4. |
- Bešenić, Krešimir, et al.
(författare)
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Picking out the bad apples : unsupervised biometric data filtering for refined age estimation
- 2023
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Ingår i: The Visual Computer. - Heidelberg, Germany : Springer. - 0178-2789 .- 1432-2315. ; 39, s. 219-237
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Tidskriftsartikel (refereegranskat)abstract
- Introduction of large training datasets was essential for the recent advancement and success of deep learning methods. Due to the difficulties related to biometric data collection, facial image datasets with biometric trait labels are scarce and usually limited in terms of size and sample diversity. Web-scraping approaches for automatic data collection can produce large amounts of weakly labeled and noisy data. This work is focused on picking out the bad apples from web-scraped facial datasets by automatically removing erroneous samples that impair their usability. The unsupervised facial biometric data filtering method presented in this work greatly reduces label noise levels in web-scraped facial biometric data. Experiments on two large state-of-the-art web-scraped datasets demonstrate the effectiveness of the proposed method with respect to real and apparent age estimation based on five different age estimation methods. Furthermore, we apply the proposed method, together with a newly devised strategy for merging multiple datasets, to data collected from three major web-based data sources (i.e., IMDb, Wikipedia, Google) and derive the new Biometrically Filtered Famous Figure Dataset or B3FD. The proposed dataset, which is made publicly available, enables considerable performance gains for all tested age estimation methods and age estimation tasks. This work highlights the importance of training data quality compared to data quantity and selection of the estimation method.
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| 5. |
- Che, X., et al.
(författare)
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A novel simulation framework based on information asymmetry to evaluate evacuation plan
- 2015
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Ingår i: The Visual Computer. - : Springer Science+Business Media B.V.. - 0178-2789 .- 1432-2315. ; 31:6-8, s. 853-861
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a novel framework to simulate the crowd behavior under emergency situations in a confined space with multiple exits. In our work, we take the information asymmetry into consideration, which is used to model the different behaviors presented by pedestrians because of their different knowledge about the environment. We categorize the factors influencing the preferred velocity into two groups, the intrinsic and extrinsic factors, which are unified into a single space called influence space. At the same time, a finite state machine is employed to control the individual behavior. Different strategies are used to compute the preferred velocity in different states, so that our framework can produce the phenomena of decision change. Our experimental results prove that our framework can be employed to analyze the factors influencing the escape time, such as the number and location of exits, the density distribution of the crowd and so on. Thus it can be used to design and evaluate the evacuation plans. © 2015 Springer-Verlag Berlin Heidelberg
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| 6. |
- Ganestam, Per, et al.
(författare)
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Real-Time Multiply Recursive Reflections and Refractions using Hybrid Rendering
- 2015
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Ingår i: Visual Computer. - : Springer Science and Business Media LLC. - 0178-2789 .- 1432-2315. ; 31:10, s. 1395-1403
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Tidskriftsartikel (refereegranskat)abstract
- We present a new method for real-time render- ing of multiple recursions of reflections and refractions. The method uses the strengths of real-time ray tracing for objects close to the camera, by storing them in a per-frame constructed bounding volume hierarchy (BVH). For objects further from the camera, rasterization is used to create G-buffers which store an image-based representation of the scene out- side the near objects. Rays that exit the BVH continue tracing in the G-buffers’ perspective space using ray marching, and can even be reflected back into the BVH. Our hybrid renderer is to our knowledge the first method to merge real- time ray tracing techniques with image-based rendering to achieve smooth transitions from accurately ray-traced fore- ground objects to image-based representations in the back- ground. We are able to achieve more complex reflections and refractions than existing screen space techniques, and offer reflections by off-screen objects. Our results demonstrate that our algorithm is capable of rendering multiple bounce reflections and refractions, for scenes with millions of triangles, at 720p resolution and above 30 FPS.
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| 7. |
- Gogic, Ivan, et al.
(författare)
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Fast facial expression recognition using local binary features and shallow neural networks
- 2020
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Ingår i: The Visual Computer. - : SPRINGER. - 0178-2789 .- 1432-2315. ; 36:1, s. 97-112
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Tidskriftsartikel (refereegranskat)abstract
- Facial expression recognition applications demand accurate and fast algorithms that can run in real time on platforms with limited computational resources. We propose an algorithm that bridges the gap between precise but slow methods and fast but less precise methods. The algorithm combines gentle boost decision trees and neural networks. The gentle boost decision trees are trained to extract highly discriminative feature vectors (local binary features) for each basic facial expression around distinct facial landmark points. These sparse binary features are concatenated and used to jointly optimize facial expression recognition through a shallow neural network architecture. The joint optimization improves the recognition rates of difficult expressions such as fear and sadness. Furthermore, extensive experiments in both within- and cross-database scenarios have been conducted on relevant benchmark data sets for facial expression recognition: CK+, MMI, JAFFE, and SFEW 2.0. The proposed method (LBF-NN) compares favorably with state-of-the-art algorithms while achieving an order of magnitude improvement in execution time.
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| 8. |
- Goswami, Prashant, 1980-
(författare)
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A survey of modeling, rendering and animation of clouds in computer graphics
- 2021
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Ingår i: The Visual Computer. - : Springer Science+Business Media B.V.. - 0178-2789 .- 1432-2315. ; 37:7, s. 1931-1948
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Tidskriftsartikel (refereegranskat)abstract
- Clouds play an important role in enhancing the realism of outdoor scenes in computer graphics (CG). Realistic cloud generation is a challenging task, which entails processes such as modeling, photorealistic rendering and simulation of the clouds. To these ends, several techniques have been proposed within the CG community in the last 4 decades with one or more of the above stated focuses. The growth of modern hardware has also enabled development of techniques that can achieve cloud display and animation at interactive frame rates. In this survey, we review the prominent work in the domain and also summarize the evolution of the research over the time. © 2020, The Author(s).
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| 9. |
- Günther, David, et al.
(författare)
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Efficient Computation of 3D Morse-Smale Complexes and Persistent Homology using Discrete Morse Theory
- 2012
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Ingår i: The Visual Computer. - : Springer Science and Business Media LLC. - 0178-2789 .- 1432-2315. ; 28:10, s. 959-969
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Tidskriftsartikel (refereegranskat)abstract
- We propose an efficient algorithm that computes the Morse–Smale complex for 3D gray-scale images. This complex allows for an efficient computation of persistent homology since it is, in general, much smaller than the input data but still contains all necessary information. Our method improves a recently proposed algorithm to extract the Morse–Smale complex in terms of memory consumption and running time. It also allows for a parallel computation of the complex. The computational complexity of the Morse–Smale complex extraction solely depends on the topological complexity of the input data. The persistence is then computed using the Morse–Smale complex by applying an existing algorithm with a good practical running time. We demonstrate that our method allows for the computation of persistent homology for large data on commodity hardware.
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| 10. |
- Gökstorp, Simon G. E., 1996-, et al.
(författare)
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Temporal and non-temporal contextual saliency analysis for generalized wide-area search within unmanned aerial vehicle (UAV) video
- 2021
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Ingår i: The Visual Computer. - : Springer Science+Business Media B.V.. - 0178-2789 .- 1432-2315. ; 38:6, s. 2033-2040
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Tidskriftsartikel (refereegranskat)abstract
- Unmanned aerial vehicles (UAV) can be used to great effect for wide-area searches such as search and rescue operations. UAV enable search and rescue teams to cover large areas more efficiently and in less time. However, using UAV for this purpose involves the creation of large amounts of data, typically in video format, which must be analysed before any potential findings can be uncovered and actions taken. This is a slow and expensive process which can result in significant delays to the response time after a target is seen by the UAV. To solve this problem we propose a deep model architecture using a visual saliency approach to automatically analyse and detect anomalies in UAV video. Our Temporal Contextual Saliency (TeCS) approach is based on the state-of-the-art in visual saliency detection using deep Convolutional Neural Networks (CNN) and considers local and scene context, with novel additions in utilizing temporal information through a convolutional Long Short-Term Memory (LSTM) layer and modifications to the base model architecture. We additionally evaluate the impact of temporal vs non-temporal reasoning for this task. Our model achieves improved results on a benchmark dataset with the addition of temporal reasoning showing significantly improved results compared to the state-of-the-art in saliency detection.
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