Calibration of a wide angle stereoscopic system

This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.36.003064. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Inaccuracies in the calibration of a stereoscopic system appear with errors in point correspondences between both images and inexact points localization in each image. Errors increase if the stereoscopic system is composed of wide angle lens cameras. We propose a technique where detected points in both images are corrected before estimating the fundamental matrix and the lens distortion models. Since points are corrected first, errors in point correspondences and point localization are avoided. To correct point location in both images, geometrical and epipolar constraints are imposed in a nonlinear minimization problem. Geometrical constraints define the point localization in relation to its neighbors in the same image, and eipolar constraints represent the location of one point referred to its corresponding point in the other image. © 2011 Optical Society of America.Ricolfe Viala, C.; Sánchez Salmerón, AJ.; Martínez Berti, E. (2011). Calibration of a wide angle stereoscopic system. Optics Letters. 36(16):3064-3067. doi:10.1364/OL.36.003064S306430673616Zhang, Z., Ma, H., Guo, T., Zhang, S., & Chen, J. (2011). Simple, flexible calibration of phase calculation-based three-dimensional imaging system. Optics Letters, 36(7), 1257. doi:10.1364/ol.36.001257Longuet-Higgins, H. C. (1981). A computer algorithm for reconstructing a scene from two projections. Nature, 293(5828), 133-135. doi:10.1038/293133a0Ricolfe-Viala, C., & Sanchez-Salmeron, A.-J. (2010). Lens distortion models evaluation. Applied Optics, 49(30), 5914. doi:10.1364/ao.49.005914Armangué, X., & Salvi, J. (2003). Overall view regarding fundamental matrix estimation. Image and Vision Computing, 21(2), 205-220. doi:10.1016/s0262-8856(02)00154-3Devernay, F., & Faugeras, O. (2001). Straight lines have to be straight. Machine Vision and Applications, 13(1), 14-24. doi:10.1007/pl0001326

4-Dimensional deformation part model for pose estimation using Kalman filter constraints

The main goal of this article is to analyze the effect on pose estimation accuracy when using a Kalman filter added to 4-dimensional deformation part model partial solutions. The experiments run with two data sets showing that this method improves pose estimation accuracy compared with state-of-the-art methods and that a Kalman filter helps to increase this accuracy

Calibration of a trinocular system formed with wide angle lens cameras

This paper was published in OPTICS EXPRESS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OE.20.027691 . Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under lawTo obtain 3D information of large areas, wide angle lens cameras are used to reduce the number of cameras as much as possible. However, since images are high distorted, errors in point correspondences increase and 3D information could be erroneous. To increase the number of data from images and to improve the 3D information, trinocular sensors are used. In this paper a calibration method for a trinocular sensor formed with wide angle lens cameras is proposed. First pixels locations in the images are corrected using a set of constraints which define the image formation in a trinocular system. When pixels location are corrected, lens distortion and trifocal tensor is computed.This work was partially funded by the Universidad Politecnica de Valencia research funds (PAID 2010-2431 and PAID 10017), Generalitat Valenciana (GV/2011/057) and by Spanish government and the European Community under the project DPI2010-20814-C02-02 (FEDER-CICYT) and DPI2010-20286 (CICYT).Ricolfe Viala, C.; Sánchez Salmerón, AJ.; Valera Fernández, Á. (2012). Calibration of a trinocular system formed with wide angle lens cameras. Optics Express. 20(25):27691-27696. doi:10.1364/OE.20.027691S27691276962025Hartley, R. I. (1997). International Journal of Computer Vision, 22(2), 125-140. doi:10.1023/a:1007936012022Torr, P. H. ., & Zisserman, A. (1997). Robust parameterization and computation of the trifocal tensor. Image and Vision Computing, 15(8), 591-605. doi:10.1016/s0262-8856(97)00010-3Ricolfe-Viala, C., Sanchez-Salmeron, A.-J., & Martinez-Berti, E. (2011). Accurate calibration with highly distorted images. Applied Optics, 51(1), 89. doi:10.1364/ao.51.000089Ricolfe-Viala, C., & Sanchez-Salmeron, A.-J. (2010). Lens distortion models evaluation. Applied Optics, 49(30), 5914. doi:10.1364/ao.49.005914Ahmed, M., & Farag, A. (2005). Nonmetric calibration of camera lens distortion: differential methods and robust estimation. IEEE Transactions on Image Processing, 14(8), 1215-1230. doi:10.1109/tip.2005.846025Devernay, F., & Faugeras, O. (2001). Straight lines have to be straight. Machine Vision and Applications, 13(1), 14-24. doi:10.1007/pl0001326

Experimental investigation on camera calibration for 3D photogrammetric scanning of micro-features for micrometric resolution

[EN] Recently, it has been demonstrated that photogrammetry can be used for the measurement of small objects with micro-features, with good results and lower cost, compared to other established techniques such as interferometry, conoscopic holography, and 3D microscopy. Calibration is a critical step in photogrammetry and the classical pinhole camera model has been tested for magnifications lower than 2×. At higher magnification levels, because of the reduction of the depth of field (DOF), images can lead to calibration data with low reprojection errors. However, this could lead to bad results in the 3D reconstruction. With the aim of verifying the possibility of applying the camera model to magnifications higher than 2×, experiments have been conducted using reflex cameras with 60 mm macro lens, equipped with the combination of three extension tubes, corresponding to 2.06, 2.23, and 2.4 magnification levels, respectively. Experiments consisted of repeating calibration five times for each configuration and testing each calibration model, measuring two artifacts with different geometrical complexity. The calibration results have shown good repeatability of a subset of the internal calibration parameters. Despite the differences in the calibration reprojection error (RE), the quality of the photogrammetric 3D models retrieved was stable and satisfying. The experiment demonstrated the possibilities of the photogrammetric system presented, equipped to very high magnification levels, to retrieve accurate 3D reconstruction of micro-features with uncertainties of few micrometers, comparable with industry s expensive state-of-the-art technologies.Percoco, G.; Guerra, MG.; Sánchez Salmerón, AJ.; Galantucci, LM. (2017). Experimental investigation on camera calibration for 3D photogrammetric scanning of micro-features for micrometric resolution. The International Journal of Advanced Manufacturing Technology. 91(9-12):2935-2947. https://doi.org/10.1007/s00170-016-9949-6S29352947919-12Uhlmann E, Mullany B, Biermann D, Rajurkar KP, Hausotte T, Brinksmeier E (2016) Process chains for high-precision components with micro-scale features. CIRP Ann - Manuf Technol 65:549–572. doi: 10.1016/j.cirp.2016.05.001Savio E, De Chiffre L, Schmitt R (2007) Metrology of freeform shaped parts. CIRP Ann - Manuf Technol 56:810–835. doi: 10.1016/j.cirp.2007.10.008Rodríguez-martín M, Lagüela S, González-aguilera D, Rodríguez-gonzálvez P (2015) Optics & Laser Technology Procedure for quality inspection of welds based on macro-photogrammetric three-dimensional reconstruction;73:54–62Xu Z, Toncich D, Stefani S (1999) Vision-based measurement of three-dimensional geometric workpiece properties. Int J Adv Manuf Technol 15:322–331. doi: 10.1007/s001700050074Galantucci LM, Lavecchia F, Percoco G (2013) Multistack close range photogrammetry for low cost submillimeter metrology. J Comput Inf Sci Eng 13:44501. doi: 10.1115/1.4024973Maté González, M.T., Yravedra, J., González-Aguilera, D., Palomeque-González, J.F., Domínguez-Rodrigo, M. Micro-photogrammetric characterization of cut marks on bones (2015) Journal of Archaeological Science, 62, pp. 128-142. doi: 10.1016/j.jas.2015.08.006Brown DC (1971) Close-range camera calibration. Photogramm Eng 37:855–866 doi:10.1.1.14.6358Tang R, Fritsch D (2013) Correlation analysis of camera self-calibration in close range photogrammetry. Photogramm Rec 28:86–95. doi: 10.1111/phor.12009Agisoft LLC (2011) Agisoft PhotoScan User Manual :37.Jcgm JCFGIM (2008) Evaluation of measurement data—guide to the expression of uncertainty in measurement- annex B "general metrological terms"- B.2.14. Int Organ Stand Geneva ISBN 50:134. doi: 10.1373/clinchem.2003.030528Yanagi, H., Chikatsu, H. Performance evaluation of macro lens in digital close range photogrammetry (2009) Proceedings of SPIE - The International Society for Optical Engineering, 7447, art. no. 74470J, doi: 10.1117/12.825817Galantucci LM, Pesce M, Lavecchia F (2015) A stereo photogrammetry scanning methodology, for precise and accurate 3D digitization of small parts with sub-millimeter sized features. CIRP Ann - Manuf Technol 64:507–510. doi: 10.1016/j.cirp.2015.04.016Galantucci LM, Pesce M, Lavecchia F (2015) A powerful scanning methodology for 3D measurements of small parts with complex surfaces and sub millimeter-sized features, based on close range photogrammetry. Precis Eng. doi: 10.1016/j.precisioneng.2015.07.010Percoco G, Sánchez Salmerón AJ (2015) Photogrammetric measurement of 3D freeform millimetre-sized objects with micro features: an experimental validation of the close-range camera calibration model for narrow angles of view. Meas Sci Technol 26:95203. doi: 10.1088/0957-0233/26/9/095203Gallo A, Muzzupappa M, Bruno F (2014) 3D reconstruction of small sized objects from a sequence of multi-focused images. J Cult Herit 15:173–182. doi: 10.1016/j.culher.2013.04.009Stamatopoulos C, Fraser CS, Cronk S (2010) On the self-calibration of long focal length lenses. Int Arch Photogramm Remote Sens Spat Inf Sci Newcastle upon Tyne, UK 2010 XXXVIII:560–564Atkinson KB (1996) Close range photogrammetry and machine vision. Whittles PublishingLuhmann T, Fraser C, Maas HG (2016) Sensor modelling and camera calibration for close-range photogrammetry. ISPRS J Photogramm Remote Sens 115:37–46. doi: 10.1016/j.isprsjprs.2015.10.006Tsai RY (1986) An efficient and accurate camera calibration technique for 3D machine vision. Proc IEEE Conf Comput Vis Pattern Recognition 1986Ricolfe-Viala C, Sanchez-Salmeron A-J (2011) Camera calibration under optimal conditions. Opt Express 19:10769–10775. doi: 10.1364/OE.19.010769Wang L, Wang W, Shen C, Duan F (2016) A convex relaxation optimization algorithm for multi-camera calibration with 1D objects. NeurocomputingRicolfe-Viala C, Sanchez-Salmeron A. Lens distortion models evaluation. Appl Opt 2010;49:5914–5928.Percoco G, Lavecchia F, Salmerón AJS (2015) Preliminary study on the 3D digitization of millimeter scale products by means of photogrammetry. Procedia CIRP 33:257–262. doi: 10.1016/j.procir.2015.06.046Bradski G (2000) The OpenCV Library. Dr Dobb’s J Softw ToolsRicolfe-Viala C, Sanchez-Salmeron A-J (2011) Optimal conditions for camera calibration using a planar template. 2011 18th IEEE. Int Conf Image Process, IEEE 2011:853–856. doi: 10.1109/ICIP.2011.6116691Lowe DG (1999) Object recognition from local scale-invariant features. Proc Seventh IEEE Int Conf Comput Vis 2:1150–1157. doi: 10.1109/ICCV.1999.790410Triggs B, Mclauchlan P, Hartley R, Fitzgibbon A, Triggs B, Mclauchlan P, et al. (2010) Bundle adjustment—a modern synthesis to cite this version: bundle adjustment—a modern synthesisCignoni P, Callieri M, Corsini M, Dellepiane M, Ganovelli F, Ranzuglia G (2008) Meshlab: an open-source mesh processing tool. Eurographics Ital Chapter Conf 2008:129–136Besl P, McKay N (1992) A method for registration of 3-D shapes. IEEE Trans Pattern Anal Mach Intell 14:239–256. doi: 10.1109/34.12179

Worldwide trends in blood pressure from 1975 to 2015: a pooled analysis of 1479 population-based measurement studies with 19.1 million participants

AbstractBackground: Raised blood pressure is an important risk factor for cardiovascular diseases and chronic kidney disease. We estimated worldwide trends in mean systolic and mean diastolic blood pressure, and the prevalence of, and number of people with, raised blood pressure, defined as systolic blood pressure of 140 mm Hg or higher or diastolic blood pressure of 90 mm Hg or higher.Methods: For this analysis, we pooled national, subnational, or community population-based studies that had measured blood pressure in adults aged 18 years and older. We used a Bayesian hierarchical model to estimate trends from 1975 to 2015 in mean systolic and mean diastolic blood pressure, and the prevalence of raised blood pressure for 200 countries. We calculated the contributions of changes in prevalence versus population growth and ageing to the increase in the number of adults with raised blood pressure.Findings: We pooled 1479 studies that had measured the blood pressures of 19.1 million adults. Global age-standardised mean systolic blood pressure in 2015 was 127.0 mm Hg (95% credible interval 125.7–128.3) in men and 122.3 mm Hg (121.0–123.6) in women; age-standardised mean diastolic blood pressure was 78.7 mm Hg (77.9–79.5) for men and 76.7 mm Hg (75.9–77.6) for women. Global age-standardised prevalence of raised blood pressure was 24.1% (21.4–27.1) in men and 20.1% (17.8–22.5) in women in 2015. Mean systolic and mean diastolic blood pressure decreased substantially from 1975 to 2015 in high-income western and Asia Pacific countries, moving these countries from having some of the highest worldwide blood pressure in 1975 to the lowest in 2015. Mean blood pressure also decreased in women in central and eastern Europe, Latin America and the Caribbean, and, more recently, central Asia, Middle East, and north Africa, but the estimated trends in these super-regions had larger uncertainty than in high-income super-regions. By contrast, mean blood pressure might have increased in east and southeast Asia, south Asia, Oceania, and sub-Saharan Africa. In 2015, central and eastern Europe, sub-Saharan Africa, and south Asia had the highest blood pressure levels. Prevalence of raised blood pressure decreased in high-income and some middle-income countries; it remained unchanged elsewhere. The number of adults with raised blood pressure increased from 594 million in 1975 to 1.13 billion in 2015, with the increase largely in low-income and middle-income countries. The global increase in the number of adults with raised blood pressure is a net effect of increase due to population growth and ageing, and decrease due to declining age-specific prevalence.Interpretation: During the past four decades, the highest worldwide blood pressure levels have shifted from high-income countries to low-income countries in south Asia and sub-Saharan Africa due to opposite trends, while blood pressure has been persistently high in central and eastern Europe.Abstract Background: Raised blood pressure is an important risk factor for cardiovascular diseases and chronic kidney disease. We estimated worldwide trends in mean systolic and mean diastolic blood pressure, and the prevalence of, and number of people with, raised blood pressure, defined as systolic blood pressure of 140 mm Hg or higher or diastolic blood pressure of 90 mm Hg or higher. Methods: For this analysis, we pooled national, subnational, or community population-based studies that had measured blood pressure in adults aged 18 years and older. We used a Bayesian hierarchical model to estimate trends from 1975 to 2015 in mean systolic and mean diastolic blood pressure, and the prevalence of raised blood pressure for 200 countries. We calculated the contributions of changes in prevalence versus population growth and ageing to the increase in the number of adults with raised blood pressure. Findings: We pooled 1479 studies that had measured the blood pressures of 19.1 million adults. Global age-standardised mean systolic blood pressure in 2015 was 127.0 mm Hg (95% credible interval 125.7–128.3) in men and 122.3 mm Hg (121.0–123.6) in women; age-standardised mean diastolic blood pressure was 78.7 mm Hg (77.9–79.5) for men and 76.7 mm Hg (75.9–77.6) for women. Global age-standardised prevalence of raised blood pressure was 24.1% (21.4–27.1) in men and 20.1% (17.8–22.5) in women in 2015. Mean systolic and mean diastolic blood pressure decreased substantially from 1975 to 2015 in high-income western and Asia Pacific countries, moving these countries from having some of the highest worldwide blood pressure in 1975 to the lowest in 2015. Mean blood pressure also decreased in women in central and eastern Europe, Latin America and the Caribbean, and, more recently, central Asia, Middle East, and north Africa, but the estimated trends in these super-regions had larger uncertainty than in high-income super-regions. By contrast, mean blood pressure might have increased in east and southeast Asia, south Asia, Oceania, and sub-Saharan Africa. In 2015, central and eastern Europe, sub-Saharan Africa, and south Asia had the highest blood pressure levels. Prevalence of raised blood pressure decreased in high-income and some middle-income countries; it remained unchanged elsewhere. The number of adults with raised blood pressure increased from 594 million in 1975 to 1.13 billion in 2015, with the increase largely in low-income and middle-income countries. The global increase in the number of adults with raised blood pressure is a net effect of increase due to population growth and ageing, and decrease due to declining age-specific prevalence. Interpretation: During the past four decades, the highest worldwide blood pressure levels have shifted from high-income countries to low-income countries in south Asia and sub-Saharan Africa due to opposite trends, while blood pressure has been persistently high in central and eastern Europe

Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants.

BACKGROUND: Hypertension can be detected at the primary health-care level and low-cost treatments can effectively control hypertension. We aimed to measure the prevalence of hypertension and progress in its detection, treatment, and control from 1990 to 2019 for 200 countries and territories. METHODS: We used data from 1990 to 2019 on people aged 30-79 years from population-representative studies with measurement of blood pressure and data on blood pressure treatment. We defined hypertension as having systolic blood pressure 140 mm Hg or greater, diastolic blood pressure 90 mm Hg or greater, or taking medication for hypertension. We applied a Bayesian hierarchical model to estimate the prevalence of hypertension and the proportion of people with hypertension who had a previous diagnosis (detection), who were taking medication for hypertension (treatment), and whose hypertension was controlled to below 140/90 mm Hg (control). The model allowed for trends over time to be non-linear and to vary by age. FINDINGS: The number of people aged 30-79 years with hypertension doubled from 1990 to 2019, from 331 (95% credible interval 306-359) million women and 317 (292-344) million men in 1990 to 626 (584-668) million women and 652 (604-698) million men in 2019, despite stable global age-standardised prevalence. In 2019, age-standardised hypertension prevalence was lowest in Canada and Peru for both men and women; in Taiwan, South Korea, Japan, and some countries in western Europe including Switzerland, Spain, and the UK for women; and in several low-income and middle-income countries such as Eritrea, Bangladesh, Ethiopia, and Solomon Islands for men. Hypertension prevalence surpassed 50% for women in two countries and men in nine countries, in central and eastern Europe, central Asia, Oceania, and Latin America. Globally, 59% (55-62) of women and 49% (46-52) of men with hypertension reported a previous diagnosis of hypertension in 2019, and 47% (43-51) of women and 38% (35-41) of men were treated. Control rates among people with hypertension in 2019 were 23% (20-27) for women and 18% (16-21) for men. In 2019, treatment and control rates were highest in South Korea, Canada, and Iceland (treatment >70%; control >50%), followed by the USA, Costa Rica, Germany, Portugal, and Taiwan. Treatment rates were less than 25% for women and less than 20% for men in Nepal, Indonesia, and some countries in sub-Saharan Africa and Oceania. Control rates were below 10% for women and men in these countries and for men in some countries in north Africa, central and south Asia, and eastern Europe. Treatment and control rates have improved in most countries since 1990, but we found little change in most countries in sub-Saharan Africa and Oceania. Improvements were largest in high-income countries, central Europe, and some upper-middle-income and recently high-income countries including Costa Rica, Taiwan, Kazakhstan, South Africa, Brazil, Chile, Turkey, and Iran. INTERPRETATION: Improvements in the detection, treatment, and control of hypertension have varied substantially across countries, with some middle-income countries now outperforming most high-income nations. The dual approach of reducing hypertension prevalence through primary prevention and enhancing its treatment and control is achievable not only in high-income countries but also in low-income and middle-income settings. FUNDING: WHO

Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants

Background Hypertension can be detected at the primary health-care level and low-cost treatments can effectively control hypertension. We aimed to measure the prevalence of hypertension and progress in its detection, treatment, and control from 1990 to 2019 for 200 countries and territories. Methods We used data from 1990 to 2019 on people aged 30–79 years from population-representative studies with measurement of blood pressure and data on blood pressure treatment. We defined hypertension as having systolic blood pressure 140 mm Hg or greater, diastolic blood pressure 90 mm Hg or greater, or taking medication for hypertension. We applied a Bayesian hierarchical model to estimate the prevalence of hypertension and the proportion of people with hypertension who had a previous diagnosis (detection), who were taking medication for hypertension (treatment), and whose hypertension was controlled to below 140/90 mm Hg (control). The model allowed for trends over time to be non-linear and to vary by age. Findings The number of people aged 30–79 years with hypertension doubled from 1990 to 2019, from 331 (95% credible interval 306–359) million women and 317 (292–344) million men in 1990 to 626 (584–668) million women and 652 (604–698) million men in 2019, despite stable global age-standardised prevalence. In 2019, age-standardised hypertension prevalence was lowest in Canada and Peru for both men and women; in Taiwan, South Korea, Japan, and some countries in western Europe including Switzerland, Spain, and the UK for women; and in several low-income and middle-income countries such as Eritrea, Bangladesh, Ethiopia, and Solomon Islands for men. Hypertension prevalence surpassed 50% for women in two countries and men in nine countries, in central and eastern Europe, central Asia, Oceania, and Latin America. Globally, 59% (55–62) of women and 49% (46–52) of men with hypertension reported a previous diagnosis of hypertension in 2019, and 47% (43–51) of women and 38% (35–41) of men were treated. Control rates among people with hypertension in 2019 were 23% (20–27) for women and 18% (16–21) for men. In 2019, treatment and control rates were highest in South Korea, Canada, and Iceland (treatment >70%; control >50%), followed by the USA, Costa Rica, Germany, Portugal, and Taiwan. Treatment rates were less than 25% for women and less than 20% for men in Nepal, Indonesia, and some countries in sub-Saharan Africa and Oceania. Control rates were below 10% for women and men in these countries and for men in some countries in north Africa, central and south Asia, and eastern Europe. Treatment and control rates have improved in most countries since 1990, but we found little change in most countries in sub-Saharan Africa and Oceania. Improvements were largest in high-income countries, central Europe, and some upper-middle-income and recently high-income countries including Costa Rica, Taiwan, Kazakhstan, South Africa, Brazil, Chile, Turkey, and Iran. Interpretation Improvements in the detection, treatment, and control of hypertension have varied substantially across countries, with some middle-income countries now outperforming most high-income nations. The dual approach of reducing hypertension prevalence through primary prevention and enhancing its treatment and control is achievable not only in high-income countries but also in low-income and middle-income settings

Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants

Background Hypertension can be detected at the primary health-care level and low-cost treatments can effectively control hypertension. We aimed to measure the prevalence of hypertension and progress in its detection, treatment, and control from 1990 to 2019 for 200 countries and territories. Methods We used data from 1990 to 2019 on people aged 30-79 years from population-representative studies with measurement of blood pressure and data on blood pressure treatment. We defined hypertension as having systolic blood pressure 140 mm Hg or greater, diastolic blood pressure 90 mm Hg or greater, or taking medication for hypertension. We applied a Bayesian hierarchical model to estimate the prevalence of hypertension and the proportion of people with hypertension who had a previous diagnosis (detection), who were taking medication for hypertension (treatment), and whose hypertension was controlled to below 140/90 mm Hg (control). The model allowed for trends over time to be non-linear and to vary by age. Findings The number of people aged 30-79 years with hypertension doubled from 1990 to 2019, from 331 (95% credible interval 306-359) million women and 317 (292-344) million men in 1990 to 626 (584-668) million women and 652 (604-698) million men in 2019, despite stable global age-standardised prevalence. In 2019, age-standardised hypertension prevalence was lowest in Canada and Peru for both men and women; in Taiwan, South Korea, Japan, and some countries in western Europe including Switzerland, Spain, and the UK for women; and in several low-income and middle-income countries such as Eritrea, Bangladesh, Ethiopia, and Solomon Islands for men. Hypertension prevalence surpassed 50% for women in two countries and men in nine countries, in central and eastern Europe, central Asia, Oceania, and Latin America. Globally, 59% (55-62) of women and 49% (46-52) of men with hypertension reported a previous diagnosis of hypertension in 2019, and 47% (43-51) of women and 38% (35-41) of men were treated. Control rates among people with hypertension in 2019 were 23% (20-27) for women and 18% (16-21) for men. In 2019, treatment and control rates were highest in South Korea, Canada, and Iceland (treatment >70%; control >50%), followed by the USA, Costa Rica, Germany, Portugal, and Taiwan. Treatment rates were less than 25% for women and less than 20% for men in Nepal, Indonesia, and some countries in sub-Saharan Africa and Oceania. Control rates were below 10% for women and men in these countries and for men in some countries in north Africa, central and south Asia, and eastern Europe. Treatment and control rates have improved in most countries since 1990, but we found little change in most countries in sub-Saharan Africa and Oceania. Improvements were largest in high-income countries, central Europe, and some upper-middle-income and recently high-income countries including Costa Rica, Taiwan, Kazakhstan, South Africa, Brazil, Chile, Turkey, and Iran. Interpretation Improvements in the detection, treatment, and control of hypertension have varied substantially across countries, with some middle-income countries now outperforming most high-income nations. The dual approach of reducing hypertension prevalence through primary prevention and enhancing its treatment and control is achievable not only in high-income countries but also in low-income and middle-income settings. Copyright (C) 2021 World Health Organization; licensee Elsevier

Camera calibration under optimal conditions

This paper was published in OPTICS EXPRESS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OE.19.010769. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under lawDifferent methods based on photogrammetry or self-calibration exist to calibrate intrinsic and extrinsic camera parameters and also for data pre- and post-processing. From a practical viewpoint, it is quite difficult to decide which calibration method gives accurate results and even whether any data processing is necessary. This paper proposes a set of optimal conditions to resolve the calibration process accurately. The calibration method uses several images of a 2D pattern. Optimal conditions define the number of points and the number of images to resolve the calibration accurately, as well as positions and orientations from where images should be taken.This work was partially funded by the Universidad Politecnica de Valencia research funds (PAID 2010-2431 and PAID 10017), Generalitat Valenciana (GV/2011/057) and by Spanish government and the European Community under the project DPI2010-20814-C02-02 (FEDER-CICYT) and DPI2010-20286 (CICYT).Ricolfe Viala, C.; Sánchez Salmerón, AJ. (2011). Camera calibration under optimal conditions. Optics Express. 19(11):10770-10776. doi:10.1364/OE.19.010769S1077010776191