Assessment of Panorama Photogrammetry as a Tool for Long-Range Deformation Monitoring.

This study investigates panorama photogrammetry (PPh) as a potential method to collect massive 3D information for long-range deformation monitoring. Particularly, this study focuses on areas with measuring restrictions, i.e., inaccessible objects and distances above 0.6 km. Under these particular conditions, geodetic techniques based on Electromagnetic Distance Meters (EDMs) or Total Stations (TSs) can provide coordinates with a precision better than 1 cm, but only for a limited number of discrete points. For mass capture, Terrestrial Laser Scanning (TLS) is normally the preferred solution, but long-range instruments are expensive, and drawbacks such as weak return signals and non-automatic target recognition appear. As an alternative, PPh is investigated in the well-controlled area of La Muela in Cortes de Pallas, where images are automatically captured from geodetic pillars using a GigaPan device, processed, and then rigorously compared to TLS point clouds. The results obtained after integrating both techniques into a high-accuracy geodetic reference frame show that PPh and TLS provide similar precision to within approximately 4 cm in the range of 0.6-1.0 km. Therefore, considering cost-effectiveness and ease of use, the proposed method can be considered a low-cost alternative to TLS for long-range deformation monitoring.

Smartphone Photogrammetric Assessment for Head Measurements.

The assessment of cranial deformation is relevant in the field of medicine dealing with infants, especially in paediatric neurosurgery and paediatrics. To address this demand, the smartphone-based solution PhotoMeDAS has been developed, harnessing mobile devices to create three-dimensional (3D) models of infants' heads and, from them, automatic cranial deformation reports. Therefore, it is crucial to examine the accuracy achievable with different mobile devices under similar conditions so prospective users can consider this aspect when using the smartphone-based solution. This study compares the linear accuracy obtained from three smartphone models (Samsung Galaxy S22 Ultra, S22, and S22+). Twelve measurements are taken with each mobile device using a coded cap on a head mannequin. For processing, three different bundle adjustment implementations are tested with and without self-calibration. After photogrammetric processing, the 3D coordinates are obtained. A comparison is made among spatially distributed distances across the head with PhotoMeDAS vs. ground truth established with a Creaform ACADEMIA 50 while-light 3D scanner. With a homogeneous scale factor for all the smartphones, the results showed that the average accuracy for the S22 smartphone is -1.15 ± 0.53 mm, for the S22+, 0.95 ± 0.40 mm, and for the S22 Ultra, -1.8 ± 0.45 mm. Worth noticing is that a substantial improvement is achieved regardless of whether the scale factor is introduced per device.

Multiband Photogrammetry and Hybrid Image Analysis for the Investigation of a Wall Painting by Paolo de San Leocadio and Francesco Pagano in the Cathedral of Valencia.

A workflow for the photogrammetric combination of non-invasive multispectral imaging techniques ranging from ultraviolet (UV) and visible (VIS) to near infrared (NIR) for the investigation of wall paintings is presented. Hereby, different methods for image analysis and visualisation techniques are discussed. This includes the combination of spectral bands in hybrid false-colour images and image analysis by applying NDVI/NDPI and PCA. The aim of the research is to generate a high-resolution photogrammetric image set, providing information on underdrawings, material differences, damages, painting techniques and conservation measures. The image data are superimposed with pixel accuracy in a geographic information system (GIS) for further analysis, tracing of observations and findings and the annotation of further information. The research is carried out on the 'Adoration of the Shepherds', an early Spanish Renaissance wall painting created in 1472 by Paolo de San Leocadio and Francesco Pagano in the Cathedral of Valencia. The wall painting is preserved in an unfinished condition, and half of it is represented by the initial plaster and preparation layers. This gives the possibility to compare and evaluate the observations of the finished areas as well as carry out an in-depth study of the working techniques.

Craniofacial 3D Morphometric Analysis with Smartphone-Based Photogrammetry.

Obtaining 3D craniofacial morphometric data is essential in a variety of medical and educational disciplines. In this study, we explore smartphone-based photogrammetry with photos and video recordings as an effective tool to create accurate and accessible metrics from head 3D models. The research involves the acquisition of craniofacial 3D models on both volunteers and head mannequins using a Samsung Galaxy S22 smartphone. For the photogrammetric processing, Agisoft Metashape v 1.7 and PhotoMeDAS software v 1.7 were used. The Academia 50 white-light scanner was used as reference data (ground truth). A comparison of the obtained 3D meshes was conducted, yielding the following results: 0.22 ± 1.29 mm for photogrammetry with camera photos, 0.47 ± 1.43 mm for videogrammetry with video frames, and 0.39 ± 1.02 mm for PhotoMeDAS. Similarly, anatomical points were measured and linear measurements extracted, yielding the following results: 0.75 mm for photogrammetry, 1 mm for videogrammetry, and 1.25 mm for PhotoMeDAS, despite large differences found in data acquisition and processing time among the four approaches. This study suggests the possibility of integrating photogrammetry either with photos or with video frames and the use of PhotoMeDAS to obtain overall craniofacial 3D models with significant applications in the medical fields of neurosurgery and maxillofacial surgery.

Spherical harmonics to quantify cranial asymmetry in deformational plagiocephaly.

Cranial deformation and deformational plagiocephaly (DP) in particular affect an important percentage of infants. The assessment and diagnosis of the deformation are commonly carried by manual measurements that provide low interuser accuracy. Another approach is the use of three-dimensional (3D) models. Nevertheless, in most cases, deformation measurements are carried out manually on the 3D model. It is necessary to develop methodologies for the detection of DP that are automatic, accurate and take profit on the high quantity of information of the 3D models. Spherical harmonics are proposed as a new methodology to identify DP from head 3D models. The ideal fitted ellipsoid for each head is computed and the orthogonal distances between head and ellipsoid are obtained. Finally, the distances are modelled using spherical harmonics. Spherical harmonic coefficients of degree 2 and order - 2 are identified as the correct ones to represent the asymmetry characteristic of DP. The obtained coefficient is compared to other anthropometric deformation indexes, such as Asymmetry Index, Oblique Cranial Length Ratio, Posterior Asymmetry Index and Anterior Asymmetry Index. The coefficient of degree 2 and order - 2 with a maximum degree of 4 is found to provide better results than the commonly computed anthropometric indexes in the detection of DP.

A Gaussian Process Model for Color Camera Characterization: Assessment in Outdoor Levantine Rock Art Scenes.

In this paper, we propose a novel approach to undertake the colorimetric camera characterization procedure based on a Gaussian process (GP). GPs are powerful and flexible nonparametric models for multivariate nonlinear functions. To validate the GP model, we compare the results achieved with a second-order polynomial model, which is the most widely used regression model for characterization purposes. We applied the methodology on a set of raw images of rock art scenes collected with two different Single Lens Reflex (SLR) cameras. A leave-one-out cross-validation (LOOCV) procedure was used to assess the predictive performance of the models in terms of CIE XYZ residuals and Δ E a b * color differences. Values of less than 3 CIELAB units were achieved for Δ E a b * . The output sRGB characterized images show that both regression models are suitable for practical applications in cultural heritage documentation. However, the results show that colorimetric characterization based on the Gaussian process provides significantly better results, with lower values for residuals and Δ E a b * . We also analyzed the induced noise into the output image after applying the camera characterization. As the noise depends on the specific camera, proper camera selection is essential for the photogrammetric work.

Low-Cost Smartphone-Based Photogrammetry for the Analysis of Cranial Deformation in Infants.

BACKGROUND: Cranial deformation, including deformational plagiocephaly, brachycephaly, and craniosynostosis, is a condition that affects a large number of infants. Despite its prevalence, there are no standards for the systematic evaluation of the cranial deformation. Usually, the deformation is measured manually by the use of calipers. Experts, however, do not agree on the suitability of these measurements to correctly represent the deformation. Other methodologies for evaluation include 3-dimensional (3D) photography and radiologic scanners. These techniques require either patient's sedation and ionizing radiation or high investment. The aim of this study is to develop a novel, low-cost, and minimally invasive methodology to correctly evaluate the cranial deformation using 3D imagery. METHODS: A smart phone was used to record a slow motion video sequence on 5 different patients. Then, the videos were processed to create accurate 3D models of the patients' head, and the results were compared with the measurements obtained by the manual caliper. RESULTS: The correspondence between the manual and the photogrammetric 3D model measurements was high as far as head marks are available, with differences of 2 mm ± 0.9 mm; without marks, measurement results differed up to 20 mm. CONCLUSIONS: Smartphone-based photogrammetry is a low-cost, highly useful methodology to evaluate cranial deformation. This technique provides a much larger quantity of information than linear measurements with a similar accuracy as far as head marks exist. In addition, a new approach for the evaluation is pointed out: the comparison between the head 3D model and an ideal head, represented by a 3-axis ellipsoid.

Evaluación de los niveles sonoros en la vida del niño en edad escolar entre seis y once años / Assessment of Sound Levels in the Life of 6 to 11-year-old Schoolchildren

En la actualidad se conocen medidas de los niveles sonoros en calles, lugares de ocio y trabajo. Sin embargo, no se han realizado medidas de los niveles sonoros en uno mismo, en la persona. Objetivó: identificar los niveles medios de presión sonora y los tiempos de exposición a los que están sometidos los niños en edad escolar. Material y método: se eligieron dos colegios de educación primaria de la ciudad de Albacete. El muestreo se hizo de forma no probabilística, seleccionamos cien niños, a los cuales se les puso un medidor individual de niveles de presión sonora. Los medidores los llevaron puestos en la parte delantera de su cuerpo durante una semana y recogían todos los sonidos recibidos. La información fue analizada con el programa SPSS v. 19.0, realizándose análisis univariantey bivariante. Resultados: la tasa de respuesta fue del 55%. El tiempo que pasan los niños en ambientes sonoros mayores a 70 dBA, que es una zona de riesgo para la salud auditiva, es el 30% y un 70,1% del tiempo correspondía a ambiente normal, por debajo de 70 dBA. Existe asociación estadística entre la edad y las actividades extraescolares con los niveles sonoros. Conclusión: los niños que no asisten a actividades extraescolares y los de menor edad soportan mayores niveles sonoros. Los alumnos de educación primaria estudiados están sometidos a sonidos elevados en su vida diaria que pueden originar pérdidas auditivas en un futuro más o menos próximo, si estos niveles persistieran en el tiempo (AU)

Currently there is awareness about sound level measurements in the street, leisure and working places. However, no measurement has been conducted of sound levels on persons themselves. Objective: to identify median levels of sound pressure and exposure times to which schoolchildren are subjected to. Materials and methods: two primary education schools were chosen in the city of Albacete. Sampling was made with a non-probability method; we selected one hundred children, who were provided with an individual meter of sound pressure levels. Children wore these meters on the front part of their bodies during a week, and all sounds received were collected. The information was analyzed with the SPSS19.0 program, and univariate and bivariate analysis was conducted. Results: the response rate was 55%. Children spent 30% of their time in sound settings above 70 dBA, which is a risk zone for auditory health; and 70.1% of their time was spent on a normal setting, below 70 dBA. There is a statistical association between age and extracurricular activities with sound levels. Conclusion: children who don’t attend extracurricular activities and those who are younger are subjected to higher sound levels. Those primary school pupils studied were subject to high sounds in their daily life, which may cause hearing loss in a more or less distant future, if those levels continue over time (AU)

Grey level and noise evaluation of a Foveon X3 image sensor: a statistical and experimental approach.

Radiometric values on digital imagery are affected by several sources of uncertainty. A practical, comprehensive and flexible procedure to analyze the radiometric values and the uncertainty effects due to the camera sensor system is described in this paper. The procedure is performed on the grey level output signal using image raw units with digital numbers ranging from 0 to 2(12)-1. The procedure is entirely based on statistical and experimental techniques. Design of Experiments (DoE) for Linear Models (LM) are derived to analyze the radiometric values and estimate the uncertainty. The presented linear model integrates all the individual sensor noise sources in one global component and characterizes the radiometric values and the uncertainty effects according to the influential factors such as the scene reflectance, wavelength range and time. The experiments are carried out under laboratory conditions to minimize the rest of uncertainty sources that might affect the radiometric values. It is confirmed the flexibility of the procedure to model and characterize the radiometric values, as well as to determine the behaviour of two phenomena when dealing with image sensors: the noise of a single image and the stability (trend and noise) of a sequence of images.

Contaminación sonora en centros públicos de educación primaria de Albacete / Noise pollution in primary education public centres of Albacete

Objetivo: determinar el nivel sonoro continuo equivalente al que se ve sometido un escolar en su actividad diaria en centros públicos de educación primaria de Albacete. Material y método: estudio observacional descriptivo y transversal en once centros públicos de educación primaria de Albacete. Variable dependiente: nivel sonoro continuo equivalente al que se ve sometido el escolar (Leq en dBA). Variables independientes: colegio y lugares del colegio. Las mediciones se han realizado utilizando medidores de sonido Bruel & Kjaer type 2.226 con trípode. Se calcularon intervalos de confianza para un 95% de seguridad. Resultados: el nivel sonoro medio equivalente en las aulas de los niños con edades entre tres y cinco años tuvo unos valores medios de 75 dBA, para edades de seis a siete años fue de 66 dBA y para edades entre 8 y 11 años fue de 69 dBA. La media de la distribución muestral(de 3 a 11 años) fue de 70 dBA. El nivel sonoro medio equivalente en el pasillo a la salida de los escolares tuvo un valor medio de 71 dBA y de 83 dBA en el patio en el momento del recreo. Conclusiones: los niveles sonoros continuos equivalentes obtenidos superan los límites establecidos por la legislación vigente para centros educativos, por tanto, los escolares están sometidos a sonidos elevados en su actividad escolar (AU)

Objective: to determine the on going noise level equivalent to the one experienced by a student in his or her daily activity in public primary schools of Albacete.Material and method: cross-sectional descriptive observational study in 11 public primary schools of Albacete. Dependent variable: ongoing noise level equal to that experienced by the student (Leq indBA). Independent variables: school and places in the school. The measurement shave been performed using type 2.226 Bruel & Kjaer sound measurers with tripod. 95% Confidence intervals were calculated. Results: the average noise level equivalent to that in the classrooms of children between the age of three and five had a mean value of 75 dBA, for ages between six and seven it was 66 dBA and for ages between 8 and 11 it was 69 dBA. The sample distribution mean (ages between 3 and 11) was 70 dBA. The average noise level equivalent in the hallway at the end of the school day had a mean value of 71 dBA and 83 dBA in the playground during break.Conclusions: the equivalent on going noise levels obtained exceed the limits established by the current legislation for schools. Therefore,students are exposed to elevated noise during their school activity (AU)