Intrinsic Light Field Images Garces, Elena; Echevarria, Jose I.; Zhang, Wen ...
Computer graphics forum,
December 2017, Volume:
36, Issue:
8
Journal Article
Peer reviewed
Open access
We present a method to automatically decompose a light field into its intrinsic shading and albedo components. Contrary to previous work targeted to two‐dimensional (2D) single images and videos, a ...light field is a 4D structure that captures non‐integrated incoming radiance over a discrete angular domain. This higher dimensionality of the problem renders previous state‐of‐the‐art algorithms impractical either due to their cost of processing a single 2D slice, or their inability to enforce proper coherence in additional dimensions. We propose a new decomposition algorithm that jointly optimizes the whole light field data for proper angular coherence. For efficiency, we extend Retinex theory, working on the gradient domain, where new albedo and occlusion terms are introduced. Results show that our method provides 4D intrinsic decompositions difficult to achieve with previous state‐of‐the‐art algorithms. We further provide a comprehensive analysis and comparisons with existing intrinsic image/video decomposition methods on light field images.
We present a method to automatically decompose a light field into its intrinsic shading and albedo components. Contrary to previous work targeted to two‐dimensional (2D) single images and videos, a light field is a 4D structure that captures non‐integrated incoming radiance over a discrete angular domain. This higher dimensionality of the problem renders previous state‐of‐the‐art algorithms impractical either due to their cost of processing a single 2D slice, or their inability to enforce proper coherence in additional dimensions. We propose a new decomposition algorithm that jointly optimizes the whole light field data for proper angular coherence.
Current exoskeleton designs have opened new ways to therapists and patients for muscle maintenance and strength recovery therapy approaches. However, some issues remain to be solved. Lack of ...adaptation, versatility, or overweight are some of the main factors that should be improved. In this article, we present a novel design for a functional modular exoskeleton composed of four independent active joints using a decentralized electronic architecture, being the first wearable exoskeleton to apply this technology. This new approach avoids the use of a main processor, and the modular scheme allows every possible configuration between the hip and knee. The decentralized electronic architecture is enabled by implementing adaptive central pattern generator (CPG) algorithms in each module controller. Each CPG has been trained to mimic the joint trajectory of a healthy person walking. The communication between modules assures their coordination through synchronization terms. The operation of each configuration was first tested on a bench at different speeds and later used by a healthy subject. These tests show how the decentralized control strategy maintains the synchronization between modules, reproducing and adapting the trained walking pattern. These results prove that our proposal is suitable for the development of exoskeletons focused on personalized therapies.
We propose a learning-based method to recover normals, specularity, and roughness from a single diffuse image of a material, using microgeometry appearance as our primary cue. Previous methods that ...work on single images tend to produce over-smooth outputs with artifacts, operate at limited resolution, or train one model per class with little room for generalization. In contrast, in this work, we propose a novel capture approach that leverages a generative network with attention and a U-Net discriminator, which shows outstanding performance integrating global information at reduced computational complexity. We showcase the performance of our method with a real dataset of digitized textile materials and show that a commodity flatbed scanner can produce the type of diffuse illumination required as input to our method. Additionally, because the problem might be ill-posed -more than a single diffuse image might be needed to disambiguate the specular reflection- or because the training dataset is not representative enough of the real distribution, we propose a novel framework to quantify the model's confidence about its prediction at test time. Our method is the first one to deal with the problem of modeling uncertainty in material digitization, increasing the trustworthiness of the process and enabling more intelligent strategies for dataset creation, as we demonstrate with an active learning experiment.
Spinal Muscular Atrophy (SMA) Type II is a neurodegenerative disease that leads to progressive muscle weakness. It prevents children from walking and affects their respiratory function and their ...activity tolerance, among other health problems. We aimed to assess the activity tolerance showed by a child with SMA using a pediatric gait exoskeleton at home when walking and performing activities.
This study presents the case of a 6-year-old boy with SMA Type II and respiratory failure who used a pediatric gait exoskeleton at home for a period of two months. A nursing assessment was done before and during the use of the device to evaluate the child's activity tolerance during the sessions. Nursing interviews, performance, vital signs, fatigue, field notes, and functional scales were analyzed.
The nursing assessment showed a good activity tolerance of the child. Performance using the device improved over time; vital signs did not vary significantly during the sessions; fatigue perception decreased over time; and the child reached a higher score on some functional outcomes.
A first step has been taken to evaluate the impact of exoskeleton technology in children with SMA Type II from the nursing point of view, exposing the potential of this technology for the care of children with neuromuscular diseases, and the need for more research on the topic.
The information in this study will be useful to nurses to know the effects of gait exoskeletons in pediatric care of children with neuromuscular diseases like SMA.
•Robotic technology is increasingly applied to pediatric care.•Lower limb robotic exoskeletons assist the gait of children who cannot walk.•A child with SMA Type II used ATLAS 2025 exoskeleton at home for two months.•This child showed a good activity tolerance using the exoskeleton.•Physical and functional performance increased during the robot assisted gait training.
The pathogenesis of renal disease in obesity and metabolic syndrome (MS) is mostly unknown. This is in part because of the limited information about renal morphological changes in these conditions. ...We evaluated renal histology in subjects with MS and those without MS, who are participants in the European Nephrectomy Biobank (ENBiBA) project.
MS was defined with at least 3 of the following criteria: (i) body mass index (BMI) ≥27 kg/m2; (ii) prediabetes: fasting glucose of 100–125 mg/dl or HbA1c >5.7%; (iii) systolic or diastolic blood pressure >140/90 mm Hg or the use of medications; and (iv) triglycerides >150 mg/dl or high-density lipoprotein cholesterol <40 (in men) or 50 mg/dl (in women). The absence of these criteria defined patients without MS. Exclusion criteria were diabetes or known causes of renal disease.
A total of 157 cases were evaluated: 49 without and 108 with MS. Those with MS were older (54 ± 16 vs. 66 ± 11, P < 0.0001), had more prevalent chronic kidney disease (CKD, estimated glomerular filtration rate eGFR <60 ml/min): 24% (23%) versus 4% (8%) (P = 0.02), and had higher albumin-to-creatinine ratio (10 4–68 vs. 4.45 0–27, P = 0.05) than those without MS. Global sclerosis (3% 1–7 vs. 7% 3–13, P < 0.0001), nodular sclerosis, mesangial expansion, glomerulomegaly; moderate + severe hyalinosis, and arteriosclerosis were more frequent in those with MS than in those without (88 82 vs. 29 59; 83 77 vs. 30 61; P < 0.05). These vascular changes were independent of differences in age.
In MS, ischemic renal disease may play a role in renal disease. In addition, some patients may develop lesions compatible with diabetic nephropathy such as increased mesangial expansion and nodular sclerosis. Further analyses are needed to study the consequences of the pandemic of obesity on renal health.
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La mortalidad de los pacientes en hemodiálisis es alta. Una tasa de ultrafiltración horaria ajustada por peso (UFR/W) elevada se ha asociado con episodios de hipotensión arterial y con mayor riesgo ...de muerte y/o eventos cardiovasculares.
Hemos evaluado la asociación entre UFR/W y mortalidad en 215 pacientes en hemodiálisis prevalentes seguidos durante 28 ± 6,12 meses. Se estimaron características clínicas basales y UFR/W media a lo largo del seguimiento.
La UFR/W media fue 9,0 ± 2,4 y los terciles 7,1 y 10,1 mL/kg/h. Se categorizó a la población en función del tiempo que habían estado con UFR/W igual o superior a los puntos de corte descritos en la literatura como relacionados con mayor mortalidad (10,0 mL/kg/h y 13,0 mL/kg/h). Los pacientes con mayor UFR/W fueron más jóvenes, con mayor ganancia de peso interdiálisis y porcentaje de reducción de peso, pero con menor peso seco, inicial y final. Durante el seguimiento, fallecieron 46 (21,4%) personas de las cuales la mayoría eran > 70 años, diabéticas o con enfermedad cardiovascular. No hubo diferencias en la mortalidad entre los grupos de UFR/W ni en la UFR/W entre los fallecidos y no fallecidos. En comparación con estudios previos donde describieron la asociación entre UFR/W y mortalidad, en nuestra población había más prevalencia de medicación protectora cardiovascular y no se observaron UFR/W tan altas.
En nuestro medio, la UFR/W más elevada se observó en pacientes más jóvenes y de menor peso y no se asoció con mayor mortalidad.
Mortality among hemodialysis patients remains high. An elevated ultrafiltration rate adjusted by weight (UFR/W) has been associated with hypotension and higher risk of death and/or cardiovascular events.
We evaluated the association between UFR/W and mortality in 215 hemodialysis patients. The mean follow-up was 28 ± 6.12 months. We collected patientś baseline characteristics and mean UFR/W throughout the follow-up.
Mean UFR/W was 9.0 ± 2,4 and tertiles 7.1 y 10.1 mL/kg/h. We divided our population according to the percentage of sessions with UFR/W above the limits described in the literature associated with increased mortality (10.0 mL/kg/h and 13.0 mL/kg/h). Patients with higher UFR/W were younger, with higher interdialytic weight gain and weight reduction percentage but lower dry, pre and post dialysis weight. Throughout the follow-up, 46 (21.4%) patients died, the majority over 70 years old, diabetic or with cardiovascular disease. There were neither differences regarding mortality between groups nor differences in UFR/W among patients who died and those who did not. Contrary to previous studies, we did not find an association between UFR/W and mortality, maybe due to a higher prevalence in the use of cardiovascular protection drugs and lower UFR/W.
The highest UFR/W were observed in younger patients with lower weight and were not associated with an increased mortality.
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