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This Letter presents a novel structured light system model that effectively considers local lens distortion by pixel-wise rational functions. We leverage the stereo method for initial calibration and then estimate the rational model for each pixel. Our proposed model can achieve high measurement accuracy within and outside the calibration volume, demonstrating its robustness and accuracy

Specular microscopy is a non-contact technique used to image the corneal endothelium (CE). The CE is primarily made up of hexagonal cells, and an accurate assessment of its health can be performed by measuring the morphometric parameters. However, traditional methods often struggle in cases of diseases, such as cornea guttata. In this thesis, we investigated the use of deep learning methods to assess CE health without manual intervention, both in healthy and pathological subjects. We present the results of using a fully convolutional regression network to predict cell density maps from input microscopy images. In addition, we present two strategies for performing cell segmentation: classification and regression. The first approach uses a 5-layer UNet architecture to classify each pixel in an input specular microscopy image into one of three categories: the cell body, diseased region, or intercellular space. The second approach, a novel regression architecture based on UNet, aims to predict signed distance maps. We compared this approach with manual references and a comercial software. Finally, we summarize our conclusions and limitations, and outline future work. Our results show that deep-learning-based methods can be a promising tool for CE health assessment, providing a more effective and automated approach.

Although there is a perception in the community that the state of optics research in Colombia has reached a mature state with international recognition, to date, there is no study that supports this view quantitatively. We aimed to assess the state of optics research in Colombia based on international journal publications. Therefore, we determined scientometric indicators using the research articles published by authors with Colombian affiliation in journals indexed in the Scopus database belonging to the Atomic and Molecular Physics and Optics subject category. The research output has increased dramatically in the past two decades, with an average of 169 articles per year since 2016. Most of these articles are published in high-impact journals. A little over 10% of that research is in the top 10% most cited in the world. Over 25 higher education institutions contribute significantly to this research with many international and national collaborations. The normalized citation impact for Colombian optics research is 0.95, only five points below the world average, and ranked second in Latin America, only superseded by Chile (1.33). Our results show that optics research is an established research area in Colombia with high impact and many active groups from different institutions spread throughout the country.

We propose modeling a structured light system with open-source computer graphics software to perform experimental verifications independently of the physical system. Encouraging experimental results show the capabilities of the digital twin. © 2022 The Author(s)

This special issue of Optica Pura y Aplicada (OPA) on Optics in Colombia compiles peer-reviewed articles by optics and photonics researchers from Colombia. The call for papers was made in May 2021 through a call published on the page of the Sociedad Red Colombiana de Óptica and was open to contributions from professionals with affiliation in Colombia in all related areas. Additionally, authors from the 2021 National Optics Meeting and the Andean and Caribbean Conference on Optics and its Applications were invited to send their contributions to this special issue. The result is a good number of contributions published in this special issue of OPA with articles by authors from different institutions in Colombia demonstrating a consolidation of optics in the country. © Sociedad Española de Óptica

We generate synthetic images with a generative adversarial network (GAN) model trained with image patches from specular microscopy corneal endothelial cells. Preliminary results show it may be a suitable approach for reliable cell segmentation. © 2022 The Author(s)

Fringe Projection Profilometry (FPP) with Digital Light Projector technology is one of the most reliable 3D sensing techniques for biomedical applications. However, besides the fringe pattern images,often a color texture image is needed for an accurate medical documentation. This image may be acquired either by projecting a white image or a black image and relying on ambient light. Color Constancy is essential for a faithful digital record, although the optical properties of biological tissue make color reproducibility challenging. Furthermore, color perception is highly dependent on the illuminant. Here, we describe a deep learning-based method for skin color correction in FPP. We trained a convolutional neural network using a skin tone color palette acquired under different illumination conditions to learn the mapping relationship between the input color image and its counterpart in the sRGB color space. Preliminary experimental results demonstrate the potential for this approach.

The implementation and generation of synthetic data for testing algorithms in optical metrology are often difficult to reproduce. In this work, we propose a framework for the generation of reproducible synthetic surface data. We present two study cases using the Code Ocean platform, which is based on Docker and Linux container technologies to turn source code repositories into executable images. i) We simulate interference pattern fringe images as acquired by a Michelson interferometric system. The reflectivity changes due to surface topography and roughness. ii) We simulate phase maps from rough isotropic surfaces. The phase data is simultaneously corrupted by noise and phase dislocations. This method relies on Gaussian-Laplacian pyramids to preserve surface features on different scales. The proposed framework enables reproducible surface data simulations, which could increase the impact of algorithm development in optical metrology.

In structured-light systems, the lens distortions of the camera and the projector reduce the measurement accuracy when calibrated as a standard stereo-vision system. The conventional compensation via distortion coefficients reduces the error, but still leaves a significant residual. Recently, we proposed a hybrid calibration procedure that leverages the standard calibration approach to improve measurement accuracy. This hybrid procedure consisted of building a pixel-wise phase-to-coordinate mapping based on adjusted 3D data obtained from the standard stereo-vision method. Here, we show experimentally that the measurement accuracy can be significantly improved, even using the linear pinhole model and linear mapping functions. We then move to consider the nonlinear model to improve the measurement accuracy further. Encouraging results show that this new calibration method increases the measurement accuracy without requiring elaborate calibration procedures or sophisticated ancillary equipment.

La monografía tiene como objetivo Realizar el análisis comparativo de soluciones hidráulicas del Canal Ricaurte: canalizaciones vs tanques de tormentas fuera de línea, para darle fiabilidad al sistema considerando la normativa vigente y así disminuir los impactos por inundación, pues se han presentado eventos inundación, por el aumento de los niveles máximo de aguas, ocasionando pérdidas económicas en diversos hogares, a pesar de las intervenciones realizadas por el Distrito de Cartagena, ya que la conducción de los canales pluviales en los ecosistemas posee un componente preponderante en las relaciones con el medioambiental, riesgo y sitio público. El estudio se enmarcó bajo un diseño analítico. Las conclusiones muestran que las regulaciones para la protección de cauces y reservas del agua no han sido aptas ni establecen una política integral para las inundaciones por precipitaciones, puesto que es importante los espacios de regreso de la lluvia. Además, las medidas físicas permiten reducir el riego de inundaciones, tomando en consideración la construcción de obras de atenuación como drenajes, alcantarillado, canales, además de las campañas de concienciación en las comunidades para el adecuado manejo de residuos sólidos, limpieza de drenajes e implementación de sistemas de alerta temprana