A tutorial on the implementations of linear image filters in CPU and GPU

This article presents an overview of the implementation of linear image filters in CPU and GPU. The main goal is to present a self contained discussion of different implementations and their background using tools from digital signal processing. First, using signal processing tools, we discuss different algorithms and estimate their computational cost. Then, we discuss the implementation of these filters in CPU and GPU. It is very common to find in the literature that GPUs can easity reduce computational times in many algorithms (straightforward implementations). In this work we show that GPU implementations not always reduce the computational time but also not all algorithms are suited for GPUs. We beleive this is a review that can help researchers and students working in this area. Although the experimental results are not meant to show which is the best implementation (in terms of running time), the main results can be extrapolated to CPUs and GPUs of different capabilities.XV Workshop de Computación Gráfica, Imágenes y Visualización (WCGIV).Red de Universidades con Carreras en Informática (RedUNCI

Temporal light field reconstruction for rendering distribution effects

Traditionally, effects that require evaluating multidimensional integrals for each pixel, such as motion blur, depth of field, and soft shadows, suffer from noise due to the variance of the high-dimensional integrand. In this paper, we describe a general reconstruction technique that exploits the anisotropy in the temporal light field and permits efficient reuse of samples between pixels, multiplying the effective sampling rate by a large factor. We show that our technique can be applied in situations that are challenging or impossible for previous anisotropic reconstruction methods, and that it can yield good results with very sparse inputs. We demonstrate our method for simultaneous motion blur, depth of field, and soft shadows

Zika virus infection in pregnancy and infant growth, body composition in the first three months of life: a cohort study.

The implications of Zika Virus exposure in pregnancy for early infant growth remains poorly described. The main goal of this study is to compare the growth, body composition, and feeding modality of infants in the first three months of life by prenatal Zika Virus exposure status. We selected an analytical cohort of 115 infants born without microcephaly, comprising 56 infants with qRT-PCR confirmed exposure to ZIKV during gestation and 59 infants born to women with presumptively no evidence of ZIKV in pregnancy. Infants were evaluated at birth, 1 and 3 months of age in terms of anthropometrics, body composition All the results were adjusted by maternal age, maternal BMI and gestational age. We observe no differences between anthropometric measurements at birth. Mothers in exposed group showed higher BMI. At 1 month and 3 months of age there were differences in mid arm circumference, arm muscle circumference and fat free mass. Weight and length was less in the ZIKV exposed in pregnancy infants and statistically different at 3 month of age. The findings of this investigation provide new evidence that ZIKV exposure in pregnancy may be associated with differences in body composition

Height from Photometric Ratio with Model-based Light Source Selection

In this paper, we present a photometric stereo algorithm for estimating surface height. We follow recent work that uses photometric ratios to obtain a linear formulation relating surface gradients and image intensity. Using smoothed finite difference approximations for the surface gradient, we are able to express surface height recovery as a linear least squares problem that is large but sparse. In order to make the method practically useful, we combine it with a model-based approach that excludes observations which deviate from the assumptions made by the image formation model. Despite its simplicity, we show that our algorithm provides surface height estimates of a high quality even for objects with highly non-Lambertian appearance. We evaluate the method on both synthetic images with ground truth and challenging real images that contain strong specular reflections and cast shadows

Foveated real-time ray tracing for head-mounted displays

Head-mounted displays with dense pixel arrays used for virtual reality applications require high frame rates and low latency rendering. This forms a challenging use case for any rendering approach. In addition to its ability of generating realistic images, ray tracing offers a number of distinct advantages, but has been held back mainly by its performance. In this paper, we present an approach that significantly improves image generation performance of ray tracing. This is done by combining foveated rendering based on eye tracking with reprojection rendering using previous frames in order to drastically reduce the number of new image samples per frame. To reproject samples a coarse geometry is reconstructed from a G-Buffer. Possible errors introduced by this reprojection as well as parts that are critical to the perception are scheduled for resampling. Additionally, a coarse color buffer is used to provide an initial image, refined smoothly by more samples were needed. Evaluations and user tests show that our method achieves real-time frame rates, while visual differences compared to fully rendered images are hardly perceivable. As a result, we can ray trace non-trivial static scenes for the Oculus DK2 HMD at 1182 × 1464 per eye within the the VSync limits without perceived visual differences.We would like to thank NVIDIA for providing us with two Quadro K6000 graphics cards as well as Intel Visual Computing Institute, the European Union (EU) for the co-funding as part of the Dreamspace and the FIWARE projects and the German Federal Ministry for Economic Affairs and Energy (BMWi) for funding the MATEDIS ZIM-project (grant no KF2644109)

Robust Poisson Surface Reconstruction

Abstract. We propose a method to reconstruct surfaces from oriented point clouds with non-uniform sampling and noise by formulating the problem as a convex minimization that reconstructs the indicator func-tion of the surface’s interior. Compared to previous models, our recon-struction is robust to noise and outliers because it substitutes the least-squares fidelity term by a robust Huber penalty; this allows to recover sharp corners and avoids the shrinking bias of least squares. We choose an implicit parametrization to reconstruct surfaces of unknown topology and close large gaps in the point cloud. For an efficient representation, we approximate the implicit function by a hierarchy of locally supported basis elements adapted to the geometry of the surface. Unlike ad-hoc bases over an octree, our hierarchical B-splines from isogeometric analysis locally adapt the mesh and degree of the splines during reconstruction. The hi-erarchical structure of the basis speeds-up the minimization and efficiently represents clustered data. We also advocate for convex optimization, in-stead isogeometric finite-element techniques, to efficiently solve the min-imization and allow for non-differentiable functionals. Experiments show state-of-the-art performance within a more flexible framework.

O que aprendemos diante dos dados que não temos? O caso da variável profissão/ocupação nos bancos de síndrome gripal, síndrome respiratória aguda grave e mortalidade no Brasil

Objective: To describe the completeness of the profession/ occupation on flu-like syndrome, severe acute respiratory syndrome and mortality databases in Brazil between 2020 and 2021 Methods:  the absolute and relative frequencies of the completeness of the variable occupation were calculated for each state for the between 2020 and 2021. Results: For the study period, there was 94.83% incompleteness for notifications of Flu-like syndrome, 97.73% for notified cases of SARS and 17.06% for deaths from all causes. Conclusions: We recommend an articulation between the Ministry of Health, Ministry of Labor and Welfare and workers' representations, such as councils and unions, to solve the problem of lack of data on occupation/profession in public databases.Objetivo: descrever o preenchimento da variável profissão/ocupação nos bancos de dados do Sistema de Informação de Mortalidade (SIM), de Síndrome Respiratória Aguda Grave (SRAG) e Síndrome Gripal (SG) entre 2020 e 2021 no Brasil. Métodos: foram calculadas as frequências absolutas e relativas do preenchimento da variável profissão/ocupação por Unidade da Federação para cada base de dados durante o período de estudo. Resultados: Para o período de estudo, verificou-se 94,83% de incompletude para as notificações de SG, 97,73% para casos notificados de SRAG e 17,06% para óbitos por todas as causas. Conclusões: Recomendamos uma articulação entre o Ministério da Saúde, Ministério do Trabalho e Previdência e representações de trabalhadores, como conselhos e sindicatos para formulação de estratégias para contornar o problema da falta de dados de ocupação/profissão nos bancos de dados públicos

Image-guided ToF depth upsampling: a survey

Recently, there has been remarkable growth of interest in the development and applications of time-of-flight (ToF) depth cameras. Despite the permanent improvement of their characteristics, the practical applicability of ToF cameras is still limited by low resolution and quality of depth measurements. This has motivated many researchers to combine ToF cameras with other sensors in order to enhance and upsample depth images. In this paper, we review the approaches that couple ToF depth images with high-resolution optical images. Other classes of upsampling methods are also briefly discussed. Finally, we provide an overview of performance evaluation tests presented in the related studies