We present in this work a calculation of the theoretical limits attainable for natural light emulation with regard to the joint optimization of the Luminous Efficacy of Radiation and color fidelity by using multiple reflectance spectra datasets, along with an implementation of a physical device that approaches these limits. A reduced visible spectrum of blackbody radiators is introduced and demonstrated which allows lamps designed to emulate natural light to operate with excellent color fidelity and higher efficiency as compared to full visible spectrum sources. It is shown that even though 3,000K and 5,500K blackbody sources have maximum efficacies of 21 lm/W and 89 lm/W, respectively, reduced-spectrum artificial light sources can exceed those values up to 363 lm/W and 313 lm/W, respectively, while retaining excellent color fidelity. Experimental demonstration approaching these values is accomplished through the design and implementation of a 12-channel light engine which emits arbitrarily-tunable spectra. The color fidelity of the designed spectra is assessed through Color Rendering Maps, showing that color fidelity is preserved uniformly over a large spectral reflectance dataset, unlike other approaches to generate white light.

This paper presents a new energy efficiency-based classification approach for street lighting. This approach considers the improvement of visual performance by correcting the standard photometry system (photopic) by the mesopic system, recommended within the CIE 191:2010 and the operational hours of the lighting system, aspects that are usually disregarded by the most-used energy classifications. The method proposed here is based on the value function concept, which allows standardizing an energy performance indicator, representing a satisfaction degree. To validate the approach proposed, a case study in 13 representative streets of the Eixample District of Barcelona is carried out, comparing results with those obtained by other three energy efficiency classifications used in Spain, Netherlands, and Italy. These results derived from the application of the method supports decision-making when using different energy classifications and straightforward to quantify potential energy savings.

La realización de este estudio responde a la necesidad de diseñar ambientes académicos que mejoren la adquisición de los conceptos en ingeniería que resultan a veces abstractos y limitan su comprensión. Utilizando metodologías cualitativas, se explora cuáles son los principales factores que los estudiantes refieren cuando evalúan las clases de ingeniería con el propósito de establecer elementos comunes entre las clases consideradas como destacadas. Para tal fin, las evaluaciones abiertas realizadas a profesores de ingeniería de la Universidad Nacional de Colombia fueron codificadas y analizadas para encontrar los temas subyacentes a categorías previamente identificadas en la literatura psicológica. Adicionalmente, se compararon los conteos de frecuencias en estos factores entre los profesores ubicados en el primer y último grupo de la evaluación cuantitativa. Los resultados mostraron que los estudiantes consideraban, dentro de la categoría de metodología, factores asociados a la evaluación, a la dinámica de clase y a la participación, y a la organización de tiempos y espacios. Finalmente, dentro de la categoría de huella docente, los estudiantes incluyeron la dedicación y el compromiso del docente, el nivel de asertividad, y la motivación y actitud. Todos estos factores diferenciaban el primer del último grupo.

Color shift keying is a modulation scheme for visible light communication that uses fixtures with three or more narrow-spectral light-emitting diodes to transmit data while fulfilling the primary function of illumination. When this modulation is used indoors, the reflectivity of the walls strongly affects the inter-channel interference and illumination quality. In this paper we present an indoor channel model that takes into account multi-wavelength propagation. This model is available as an open-source Python package. The model calculates the inter-channel interference, illuminance, correlated color temperature, and color rendering index at the receiver position. The Python package includes a module for estimating the symbol error rate. To validate the model, we computed the received power at each color photodetector for four different indoor scenarios. The model demonstrated a color rendering index of less than 15 when using IEEE-based color shift keying and non-uniform illumination on a horizontal plane. The simulation determined the required luminous flux to achieve a symbol error rate of less than ${10}^{-5}$ when the photodetector is at the center of the indoor space and vertically below the light source. To maintain a symbol error rate less than ${10}^{-5}$, the luminous flux increases when the photodetector is displaced in a diagonal direction from the center of the plane.

Physically based rendering and immersive virtual reality are emerging as powerful tools for lighting design and visual evaluation. However, existing simulation tools often fail to reproduce the photometric and colorimetric characteristics of real-world environments when visualized in virtual reality. Accurate modeling of lighting and material behavior in Immersive Virtual Reality requires methodologies that bridge physical measurements with rendered visual output. Despite recent progress, methods for aligning real and virtual scenes photometrically and colorimetrically remain limited. This work presents a novel methodology that integrates spectral and photometric measurements with perceptual metrics and optimization algorithms to calibrate parameters of lighting and materials in physically-based rendered environments. We introduce two algorithms: one to compute an optimized RGB transformation matrix derived from spectral reflectance data, and another to adjust lighting and material properties by minimizing a composite perceptual metric that measures both colour and image structure. The results show that this approach enables automatic estimation of the physically-based rendering properties of light sources and materials. It also improves the colour space representation for virtual reality displays. A perceptual study involving 23 participants demonstrated high agreement between the appearance of real and virtual colours and produced strong scores on visual realism ( Q ₂ = 4.0/5.0) and satisfaction ( Q ₁₆ = 4.8/5.0). These findings demonstrate that integrating Physically Based Rendering with a perceptual metric enables the generation of photometrically and visually realistic scenes in Immersive Virtual Reality environments.