Sensores hiperespectrales aerotransportados: eliminación del efecto de deriva

En este artículo se explican los conceptos básicos de los sensores hiperespectrales rotacionales aerotransportados. Así mismo, se hace una revisión de las diferentes circunstancias causantes de los errores en la formación de las imágenes y se propone una metodología para corregirlas. A continuación, mostramos un ejemplo práctico en el que se observa cómo la consideración y eliminación del efecto de deriva permite georreferenciar con alta precisión imágenes hiperespectrales tomadas con sensores rotacionales

Macro Photogrammetry & Surface Features Extraction for Paleolithic Portable Art Documentation

[EN] In this article, we propose a methodology for the archaeological documentation of limestone plaquettes decorated with faint paintings and fine engravings. The plaquette number 16330 is presented, belonging to the portable art collection in Cova del Parpalló (Gandía, Spain), one of the most important Paleolithic sites in the UNESCO¿s Rock Art of the Mediterranean Basin on the Iberian Peninsula. Macro photogrammetry is used to generate a 3D model and basic treatments on raster images. The resulting 3D model has a spatial resolution of tens of microns and was used to generate a digital elevation model (DEM) and orthorectified macro photographs for documenting the engravings and paintings. All stages of the workflow are detailed in-depth, specifying the data collection parameters and the configuration used in the subsequent processing with HyperCube and DStretch software. The resulting documentation is accurate, reproducible, and objective and allows the reinterpretation of the available graphic documentation started in the 1990s.This research was funded by Generalitat Valenciana (PROMETEO/2017/060) and Ministerio de la Ciencia e Innovación (HAR2017-85153-P).Cabrelles, M.; Lerma, JL.; Villaverde, V. (2020). Macro Photogrammetry & Surface Features Extraction for Paleolithic Portable Art Documentation. Applied Sciences. 10:1-16. https://doi.org/10.3390/app10196908S11610Porter, S. T., Huber, N., Hoyer, C., & Floss, H. (2016). Portable and low-cost solutions to the imaging of Paleolithic art objects: A comparison of photogrammetry and reflectance transformation imaging. Journal of Archaeological Science: Reports, 10, 859-863. doi:10.1016/j.jasrep.2016.07.013Cassen, S., Lescop, L., Grimaud, V., & Robin, G. (2014). Complementarity of acquisition techniques for the documentation of Neolithic engravings: lasergrammetric and photographic recording in Gavrinis passage tomb (Brittany, France). Journal of Archaeological Science, 45, 126-140. doi:10.1016/j.jas.2014.02.019López-Menchero Bendicho, V. M., Marchante Ortega, Á., Vincent, M., Cárdenas Martín-Buitrago, Á. J., & Onrubia Pintado, J. (2017). Uso combinado de la fotografía digital nocturna y de la fotogrametría en los procesos de documentación de petroglifos: el caso de Alcázar de San Juan (Ciudad Real, España). Virtual Archaeology Review, 8(17), 64. doi:10.4995/var.2017.6820Jalandoni, A., & Kottermair, M. (2018). Rock art as microtopography. Geoarchaeology, 33(5), 579-593. doi:10.1002/gea.21677Defrasne, C. (2014). Digital image enhancement for recording rupestrian engravings: applications to an alpine rockshelter. Journal of Archaeological Science, 50, 31-38. doi:10.1016/j.jas.2014.06.010Le Quellec, J.-L., Duquesnoy, F., & Defrasne, C. (2015). Digital image enhancement with DStretch ® : Is complexity always necessary for efficiency? Digital Applications in Archaeology and Cultural Heritage, 2(2-3), 55-67. doi:10.1016/j.daach.2015.01.003Evans, L., & Mourad, A.-L. (2018). DStretch® and Egyptian tomb paintings: A case study from Beni Hassan. Journal of Archaeological Science: Reports, 18, 78-84. doi:10.1016/j.jasrep.2018.01.011Rodríguez González, E., Pastor, S. C., & Casals, J. R. (2019). Lost colours: Photogrammetry, image analysis using the DStretch plugin, and 3-D modelling of post-firing painted pottery from the south west Iberian Peninsula. Digital Applications in Archaeology and Cultural Heritage, 13, e00093. doi:10.1016/j.daach.2019.e00093Domingo, I., García-Argüelles, P., Nadal, J., Fullola, J. M., Lerma, J. L., & Cabrelles, M. (2019). Humanizing European Paleolithic art: A new visual evidence of human/bird interactions at L’Hort de la Boquera site (Margalef de Montsant, Tarragona, Spain). L’Anthropologie, 123(1), 1-18. doi:10.1016/j.anthro.2019.01.001Menna, F., Nocerino, E., Morabito, D., Farella, E. M., Perini, M., & Remondino, F. (2017). AN OPEN SOURCE LOW-COST AUTOMATIC SYSTEM FOR IMAGE-BASED 3D DIGITIZATION. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLII-2/W8, 155-162. doi:10.5194/isprs-archives-xlii-2-w8-155-2017Porter, S. T., Roussel, M., & Soressi, M. (2016). A Simple Photogrammetry Rig for the Reliable Creation of 3D Artifact Models in the Field. Advances in Archaeological Practice, 4(1), 71-86. doi:10.7183/2326-3768.4.1.71Angheluță, L. M., & Rădvan, R. (2019). MACRO PHOTOGRAMMETRY FOR THE DAMAGE ASSESSMENT OF ARTWORK PAINTED SURFACES. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLII-2/W15, 101-107. doi:10.5194/isprs-archives-xlii-2-w15-101-2019Menna, F., Nocerino, E., Remondino, F., Dellepiane, M., Callieri, M., & Scopigno, R. (2016). 3D DIGITIZATION OF AN HERITAGE MASTERPIECE - A CRITICAL ANALYSIS ON QUALITY ASSESSMENT. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLI-B5, 675-683. doi:10.5194/isprsarchives-xli-b5-675-2016Lerma, J. L., Navarro, S., Cabrelles, M., & Seguí, A. E. (2010). Camera Calibration with Baseline Distance Constraints. The Photogrammetric Record, 25(130), 140-158. doi:10.1111/j.1477-9730.2010.00579.xDíaz-Guardamino, M., García Sanjuán, L., Wheatley, D., & Rodríguez Zamora, V. (2015). RTI and the study of engraved rock art: A re-examination of the Iberian south-western stelae of Setefilla and Almadén de la Plata 2 (Seville, Spain). Digital Applications in Archaeology and Cultural Heritage, 2(2-3), 41-54. doi:10.1016/j.daach.2015.07.002Quesada, E., & Harman, J. (2019). A step further in rock art digital enhancements. DStretch on Gigapixel imaging. Digital Applications in Archaeology and Cultural Heritage, 13, e00098. doi:10.1016/j.daach.2019.e0009

Accuracy analysis of a mobile mapping system for close range photogrammetric projects

[EN] Image-based mapping solutions require accurate exterior orientation parameters independently of the cameras used for a survey. This paper analyses the inclusion of up to two stereo-based geometric constraints in the form of baseline distance and convergence angle between camera axes to boost the integrated sensor orientation performance on outdoor close-range projects. A terrestrial low-cost mobile mapping GNSS/IMU multi-camera system is used to test the performance of the stereo-based geometric constraint on a weak geometric network in a stop-and-go survey. The influence of the number of control points (CPs) is analysed to confirm the performance and usability of the geometric constraints in real live terrestrial projects where far from ideal setups can exist across the survey. Improvements in image residuals up to 9 times and deviation errors better than 1 cm are expected when at least three CPs are incorporated into the adjustmentThe authors gratefully acknowledge the support from the Spanish Ministerio de Economia y Competitividad to the project HAR2014-59873-R. Contributions on direct georeferencing from professors Dr. David Hernandez-Lopez, Dr. Luis Garcia-Asenjo and D. Pascual Garrigues are highly appreciated.Navarro Tarin, S.; Lerma García, JL. (2016). Accuracy analysis of a mobile mapping system for close range photogrammetric projects. Measurement. 93:148-156. https://doi.org/10.1016/j.measurement.2016.07.0301481569

Spherical harmonics to quantify cranial asymmetry in deformational plagiocephaly

[EN] 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.This article was funded by Instituto de Salud Carlos III and European Regional Development Fund (FEDER) (Grant no. PI18/00881).Grieb, J.; Barbero-García, I.; Lerma, JL. (2022). Spherical harmonics to quantify cranial asymmetry in deformational plagiocephaly. Scientific Reports. 12(1):1-10. https://doi.org/10.1038/s41598-021-04181-z11012

8th. International congress on archaeology computer graphica. Cultural heritage and innovation

El lema del Congreso es: 'Documentación 3D avanzada, modelado y reconstrucción de objetos patrimoniales, monumentos y sitios.Invitamos a investigadores, profesores, arqueólogos, arquitectos, ingenieros, historiadores de arte... que se ocupan del patrimonio cultural desde la arqueología, la informática gráfica y la geomática, a compartir conocimientos y experiencias en el campo de la Arqueología Virtual. La participación de investigadores y empresas de prestigio será muy apreciada. Se ha preparado un atractivo e interesante programa para participantes y visitantes.Lerma García, JL. (2016). 8th. International congress on archaeology computer graphica. Cultural heritage and innovation. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/73708EDITORIA

Craniofacial 3D Morphometric Analysis with Smartphone-Based Photogrammetry

[EN] 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.Instituto de Salud Carlos III under project number PI22/01416 and joint financing by the European UnionQuispe-Enriquez, OC.; Valero-Lanzuela, JJ.; Lerma, JL. (2024). Craniofacial 3D Morphometric Analysis with Smartphone-Based Photogrammetry. Sensors. 24(1). https://doi.org/10.3390/s2401023024

Valoración de la calidad de imágenes panorámicas esféricas

[EN] In recent years, the production of panoramic images has been boosted by the increasing use of digital photographiccameras and mobile phones. However, for highly demanding applications such as long-range deformation monitoring, theaccuracy and quality control of panoramic images and processes used to obtain accurate 3D models should be properlyassessed. Therefore, prior to being applied in real projects, the quality of the spherical panoramic images generated bythree widely used computer programs (Agisoft Metashape, GigaPan Stitch and PTGui) is evaluated using the same imagesof a photogrammetric laboratory full of control points and an outdoor environment by shooting from several stations. Inaddition to the assessment of the geometrical accuracy, the study also includes important aspects for practical efficiencysuch as workflow, speed of processing, user-friendliness, or exporting products and formats available. The results of thecomparisons show that Agisoft Metashape meets the required geometric specifications with higher quality and has clearadvantages in performance if compared to the other two tested programs.[ES] En los últimos años, la producción de imágenes panorámicas se ha visto impulsada por el uso cada vez mayor de cámaras fotográficas digitales y teléfonos móviles. Sin embargo, deben evaluarse adecuadamente en aplicaciones altamente exigentes como la monitorización de deformaciones a grandes distancias, la precisión y el control de calidad de las imágenes panorámicas y los procesos utilizados para obtener modelos 3D precisos. Por consiguiente, antes de ser aplicadas en proyectos reales, se evalúa la calidad de las imágenes panorámicas esféricas generadas por tres programas informáticos ampliamente utilizados (Agisoft Metashape, GigaPan Stitch y PTGui) utilizando las mismas imágenes de un laboratorio fotogramétrico lleno de puntos de apoyo y del exterior desde varias estaciones. Además de la evaluación de la precisión geométrica, el estudio también incluye aspectos importantes para la eficiencia práctica como es el flujo de trabajo, la velocidad de procesamiento, la facilidad de uso o la exportación de productos y los formatos disponibles. Los resultados de las comparaciones muestran que Agisoft Metashape cumple con las especificaciones geométricas requeridas con mayor calidad y tiene claras ventajas de rendimiento si se compara con los otros dos programas testeados.Javadi, P.; Lerma, J.; García-Asenjo, L.; Garrigues, P. (2021). Quality assessment of spherical panoramic images. En Proceedings 3rd Congress in Geomatics Engineering. Editorial Universitat Politècnica de València. 7-14. https://doi.org/10.4995/CiGeo2021.2021.12728OCS71

Heuristic method based on voting for extrinsic orientation through image epipolarization

[EN] Traditionally, the stereo-pair rectification, also known as epipolarization problem, (i.e., the projection of both images onto a common image plane) is solved once both intrinsic (interior) and extrinsic (exterior) orientation parameters are known. A heuristic method is proposed to solve both the extrinsic orientation problem and the epipolarization problem in just one single step. The algorithm uses the main property of a coplanar stereopair as fitness criteria: null vertical parallax between corresponding points to achieve the best stereopair. Using an iterative approach, each pair of corresponding points will vote for a rotation axis that may reduce vertical parallax. The votes will be weighted, the rotation applied, and an iteration will be carried out, until the vertical parallax residual error is below a threshold. The algorithm performance and accuracy are checked using both simulated and real case examples. In addition, its results are compared with those obtained using a traditional nonlinear least-squares adjustment based on the coplanarity condition. The heuristic methodology is robust, fast, and yields optimal results.The authors gratefully acknowledge the support from the Spanish Ministerio de Economia y Competitividad to the Project No. HAR2014-59873-R.Martín, S.; Lerma García, JL.; Uzkeda, H. (2017). Heuristic method based on voting for extrinsic orientation through image epipolarization. Journal of Electronic Imaging. 26(6):063020-1-063020-11. https://doi.org/10.1117/1.JEI.26.6.063020S063020-1063020-1126