Footskate is a common problem encountered in interactive applications dealing with virtual character animations. It has proven difficult to fix without the use of complex numerical methods, which require expert skills for their implementations, along with a fair amount of user interaction to correct a motion. On the other hand, deformable bodies are being increasingly used in virtual reality (VR) applications, allowing users to customize their avatar as they wish. This introduces the need of adapting motions without any help from a designer, as a random user seldom has the skills required to drive the existing algorithms towards the right solution. In this paper, we present a simple method to remove footskate artifacts in VR applications. Unlike previous algorithms, our approach does not rely on the skeletal animation to perform the correction but rather on the skin. This ensures that the final foot planting really matches the virtual character’s motion. The changes are applied to the root joint of the skeleton only so that the resulting animation is as close as possible to the original one. Eventually, thanks to the simplicity of its formulation, it can be quickly and easily added to existing frameworks. 相似文献
The strengths of porous phosphate glass-ceramic specimens, with relative densities ranging between 0.25 and 0.50, were measured by four-point bending at room temperature. An analysis of the data, using Weibull statistics, indicated that such a treatment, usually performed on dense ceramics, can also be used on porous materials. In the sets studied, the nature of critical flaws was determined, which led to the proposal of a mechanism of fracture initiation in such porous materials. 相似文献
Kaolinites with various degrees of structural order and iron content were heated and subsequently analyzed via electron paramagnetic resonance. Iron was present in two different states in the heated materials, either as dilute structural Fe3+ ions or in concentrated Fe3+ phases. During metakaolinization, the environment of dilute Fe3+ ions changed, following modifications of the Al3+ coordination, and the Fe3+ concentration increased. With the breakdown of metakaolinite, the diffusion of Fe3+ ions induced their exsolution in superparamagnetic iron-rich domains (Fe3+ clusters in γ-Al2O3 and/or Fe3+ oxide nanophases), which produced a decrease in the dilute Fe3+ concentration. The subsequent breakdown of γ-Al2O3 and the formation of mullite made the dilute Fe3+ concentration increase again, because of the incorporation of Fe3+ ions in the mullite structure. 相似文献
Monitoring the response of land ice to climate change requires accurate and repeatable topographic surveys. The SPOT5-HRS (High Resolution Stereoscopic) instrument covers up to 120 km by 600 km in a single pass and has the potential to accurately map the poorly known topography of most glaciers and ice caps. The acquisition of a large HRS archive over ice-covered regions is planned by the French Space Agency (CNES) and Spotimage, France during the 2007–2008 International Polar Year (IPY). Here, we report on the accuracy and value of HRS digital elevation model (DEM) over ice and snow surfaces.
A DEM is generated by combining tools available from CNES with the PCI OrthoengineSE software, using HRS images acquired in May 2004 over South-East Alaska (USA) and northern British Columbia (Canada). The DEM is evaluated through comparison with shuttle radar topographic mission (SRTM) DEM and ICESAT data, on and around the glaciers. A horizontal shift of 50 m is found between the HRS and SRTM DEMs and is attributed to errors in the SRTM DEM. Over ice-free areas, HRS elevations are 7 m higher than those of SRTM, with a standard deviation of ± 25 m for the difference between the two DEMs. The 7-m difference is partly attributed to the differential penetration of the electromagnetic waves (visible for HRS; microwave for SRTM) in snow and vegetation.
We also report on the application of sequential DEMs (SRTM DEM in February 2000 and HRS DEM in May 2004) for the monitoring of glacier elevation changes. We map the topographic changes induced by a surge of one tributary of Ferris Glacier. Maximum surface lowering of 42 (± 10) m and rising of 77 (± 10) m are observed in the 4 years time interval. Thinning rates up to 10 (± 2.5) m/yr are observed at low altitudes and confirm the ongoing wastage of glaciers in South-East Alaska. 相似文献
This paper presents the advantages of a Branch Eigenmodes Reduced Model used in a control process of a heating system.The experimental setup is a 3D heat conductive system in which a heat source is set. First, the reduced model is used to solve the non-linear Inverse Heat Conduction Problem: identification of the heat source strength variations from time-varying temperatures. Then, the reduced model is used to control hot points in the system. The objective of the method is to allow sequential temperature control by decreasing the computation time necessary for the simulation. 相似文献
High-purity magnesium and titanium have been examined in order to study modifications to the near-surface layer during friction. Upsetting tests were conducted under atmospheric and imposed hydrostatic pressure to assess the plasticity and deformability of these metals. It is shown that the deformability of magnesium and to a lesser extent that of titanium can be considerably enhanced by superimposed hydrostatic pressure. Both metals were subjected to uniaxial, constant load, dry friction, pin-on-plate tests in air at room temperature and atmospheric pressure and the near-surface layer examined destructively and non-destructively in order to characterize induced changes. High-resolution X-ray diffraction examination of the worn and unworn surfaces suggested that the deformability of the near-surface layer in magnesium is associated with an increase in 〈a〉 Burgers vector screw dislocations able to cross slip and which contribute to recovery and recrystallization in the deformed region. A similar effect may be present for titanium although no recrystallization was observed. 相似文献
The optimal use of process water becomes increasingly important since natural water resources are heavily solicited by a growing
economy. Two steps can be considered in the process water optimization. A first step is the inventory of the different process
streams in the process water network. Pure mathematical modeling of a dynamic water network is extremely complicated and expensive.
As an approximation, the use of a steady-state network node model within commercial software is accepted to set up a water
balance. Sophisticated software tools are available but common solver software may offer an alternative. A second step is
the water “pinch” which searches for an optimal use of process water by combining sources and sinks, taking into account contaminant
concentrations of process streams. Sophisticated pinch software can be applied but it is also possible to implement a simplified
combinatory approach. Such approach can be pragmatically programmed in e.g., Visual Basic. Such tool allows for a first evaluation
of the complex combinatory sources–sinks problem, enabling a low cost and easy-to-handle first interpretation of possible
water-reuse opportunities. This could stimulate a further enhanced analysis with more advanced software tools and therefore
promote a sustainable use of process water in the industrialized world. 相似文献
This paper describes a novel robotic wheelchair, and reports experiments to evaluate its efficiency and understand how human operators use it. The concept at the heart of the collaborative wheelchair assistant (CWA) is to rely on the user's motion planning skills while assisting the maneuvering with flexible path guidance. The user decides where to go and controls the speed (including start and stop), while the system guides the wheelchair along software-defined guide paths. An intuitive path editor allows the user to avoid dangers or obstacles online and to modify the guide paths at will. By using the human sensory and planning systems, no complex sensor processing or artificial decision system is needed, making the system safe, simple, and low-cost. We investigated the performance of the CWA on its interaction with able-bodied subjects and motion efficiency. The results show that path guidance drastically simplifies the control. Using the CWA, the wheelchair user needs little effort from the first trial, while moving efficiently with a conventional wheelchair requires adaptation. 相似文献
Despite the frequency of traumatic injuries due to road accidents and potential importance of identifying children at risk of impaired recovery one year after a road accident, there is a lack of data on long-term recovery of health status, except in children with severe traumatic brain injury. The aim of the present study was to evaluate predictive factors of recovery in children one year after road traffic injuries. The prospective cohort study was composed of children aged <16 years, admitted to public or private sector hospitals in the Rhône administrative area of France following a road accident. Recovery of health status one year after the accident and information concerning quality of life and the consequences of the accident for the child or family 1 year after the accident were collected by questionnaire, usually completed by the parents. Victims were in majority male (64.6%) and had mild or moderate injuries (81.9% with Maximum Abbreviated Injury Scale (M-AIS) <3). One year after the accident, 75.0% of the mild-to-moderate and 34.8% of the severe cases estimated health status as fully recovered. After adjustment, severity score (M-AIS ≥ 3) and lower limb injury (AIS > 1) were associated with incomplete recovery of health status: weighted odds ratio (ORw), 4.3 [95% confidence interval (95% CI), 1.3–14.6] and ORw, 6.5 [95% CI, 1.9–21.7], respectively. Recovery status correlated significantly with quality of life physical scores (r = 0.46), especially body pain (r = 0.48) and role/social–physical (r = 0.50) and, to a lesser extent, quality of life psychosocial scores (r = 0.21). In a cohort of children injured in a road accident, those with high injury severity score and those with lower limb injuries are less likely to recover full health status by 1 year. Impaired health status was associated with a lower physical quality of life score at 1 year. 相似文献