Diego González Aguilera research stay at Visual Attention Lab (Boston, USA)

  Diego González Aguilera research stay at Visual Attention Lab

Diego Gonzalez Aguilera was invited by the Visual Attention Lab (Dr. Marc Pomplun) in the University of Massachusset (Boston, USA) for carrying out a research stay during 3 months (July-October, 2015). The research was focused on advancing methods and algorithms for connecting visual attention and photogrammetry. In particular, a connection between photogrammetry and the visual attention devices (Eye Tracker) was proposed. More precisely, we took advantage of the algorithms and approaches of photogrammetry to integrate them in the visual attention workflow. To this end, we exploited the General Method of Photogrammetry (GMP) making a parallelism between its main steps and those required by the eye trackers. As a result we aimed to improve the precision and reliability of the eye tracker measurements: from its calibration and determination of eye pose to the computation of visual attention object’s coordinates (gaze position). We also tried to improve the current applications performed on the laboratory and under a 2D context, extending towards the visual attention in a 3D environment. 

Understand the basis of photogrammetry and its principles entails to advance in the knowledge and comprehension of the human vision and how we are able to perceive the reality through eyes in three dimensions. The acquisition of reality through the vision system involves that the light rays (coming from natural or artificial light source) reach and pass through the eyes, which are sensible to the electromagnetic radiation of specific wavelengths (i.e. visible spectrum). In particular, when the light comes into the eye passes through the cornea, the pupil and the crystalline, arriving to the retina where the electromagnetic energy is converted into nerve impulses that can be used by the brain. These impulses leave the eye through the optic nerve. In photogrammetric terms, the region most important of the eye is located around a small region in the retina well-known as fovea. At this place all the light coming from the field of view is focused what is equivalent to the field of view of the camera. However, it should be remarked that although the field of view of each eye separately is around 120º-200º and 130º for the overlap area of both eyes (i.e. equivalent to the fisheye objectives), the retina’s effective region is only between 40-60º (even less if we are focusing on small objects at very close distances). So, the rest of the field of view of the eye is only useful for perceiving large objects or movements. Likewise, for the digital cameras this field of view is dependent of two main geometric parameters (focal length and sensor size) which are perfectly defined, whereas for the human vision this is complicated since the eye is curved and the level of detail decreases as we move away from the fovea’s center.


The next figure outlines the relationship between the geometry of the human eye with the geometry of the camera lens.

Diego González Aguilera research stay at Visual Attention Lab

Geometric eye model. (a) Outer view and (b) cross-section of the human eye with important components marked red. (c) Geometric eye model with components involved in the eye pose estimation.

The next figure outlines some of the experiments performed trying to improve eye-tracker calibration and thus to improve eye-tracker measurements.

Diego González Aguilera research stay at Visual Attention LabEyeLink 1000 during the experimental tests performed.

Diego González Aguilera research stay at Visual Attention Lab

Collaboration stay of Monica Herrero Huerta at The Technological University Of Delft (The Netherlands)


Visit to the Dutch meteorological institute KNMI in Utrecht with the Remote Sensing group of TUDelft.

Collaboration stay of Monica Herrero Huerta at the Technological University of Delft (The Netherlands) from February to July 2015 in the department of Geoscience and Remote Sensing.

The stay was focused on the direct participation in the FP7 project IQmulus (http://iqmulus.eu/), “A High-volume Fusion and Analysis Platform for Geospatial Point Clouds, Coverages and Volumetric Data Sets”, led by Dc. Roderik Linderbergh. Specifically, the research was centered on:

  • Data processing through Laser Mobile Mapping System (LMMS) to extract sizes and locations of urban trees. This work considers the automated,large scale extraction of parameters of trees sampled by a laser mobile mapping system. The input point clouds areconsecutivelydownsampled,retiled, classified and segmentedintoindivual trees. The applicationofLMMS enables to fast and accurately capture 3D data of individual trees along the road.


  • Extraction of tree geometrical parameters coming from LMMS for direct application in urban trees inventories. A non-invasive low-cost, precise and innovative methodology was developing, to automatically obtain the diameter at breast height (DBH) of urban trees destined for inventories based on point clouds by LMMS. Among the various urban tree measurements, DBH is an important tree inventory attribute because it serves as a fundamental parameter in tree allometry and estimation of basal area, thus providing valuable information about individual trees and tree stand structure.


The work will be presented at the ISPRS geospatial week in La Grande Motte (France) between 28th October and 3rd Setpember 2015.

Pablo Rodríguez-Gonzálvez research stay at 3D Optical Metrology (3DOM, Italy)

Pablo Rodríguez Gonzálvez research stay at 3D Optical Metrology
Research stay at the Bruno Kessler Foundation (FBK) and its 3D Optical Metrology (3DOM) research unit from September to November, 2014, under the supervision of Dr. Fabio Remondino. 

 The stay was focused in photogrammetry, surveying, laser scanning and 3D modelling. The specific research topics were:


  • 3D documentation of complex World War I scenarios in the framework of the VAST Project (VAlorizzazione Storia e Territorio – Valorization of History and Landscape, http://vast.fbk.eu/). Concretely, the tasks were focused in the efficient complexity reduction for information dissemination purposes, but keeping the maximum amount of significant information. As result of the Lusern fort documentation, a simplification pipeline was proposed in order to prioritize the mesh level of detail or a smooth continuous geometry, but always with the minimum number of triangles according to a specific spatial resolution. Also, photogrammetric tests to survey and model underground tunnels as a low-cost alternative were carried out, and evaluated in terms of a-prioir and a-posteriori error. 
  • Geometric assessment of a Mobile Mapping System (MMS) using advanced statistical methods. The new system VMX-450 (Riegl) precision and accuracy was evaluated in the framework of a challenge test site: the historic city centre of Trento. Non-normal statistics were employed thus a more appropriate assessment of precision and accuracy, and contrasted against reference measures are derived from photogrammetric and Terrestrial Laser Scanning (TLS) surveys. 
  • Characterization of a spherical camera for the 3D reconstruction of different environments. Several tests for the camera geometric characterization were carried out, as well automatic 3D reconstruction of indoor and outdoor scenes (Trento cathedral).


Pablo Rodríguez Gonzálvez research stay at 3D Optical Metrology

Geometric assessment of a Mobile Mapping System (MMS) using advanced statistical methods. The new system VMX-450 (Riegl) precision and accuracy was evaluated in the framework of a challenge test site: the historic city centre of Trento. Non-normal statistics were employed thus a more appropriate assessment of precision and accuracy, and contrasted against reference measures are derived from photogrammetric and Terrestrial Laser Scanning (TLS) surveys.

Pablo Rodríguez Gonzálvez research stay at 3D Optical Metrology

Luis Javier Sánchez Aparicio research stay at Historical and Masonry Structures group (Guimarães,Portugal)

Research stay of Luis Javier Sánchez Aparicio at the University of Minho (Portugal) and its research group Historical and Masonry Structures (http://www.hms.civil.uminho.pt/) from March to June, 2014, under the supervision of Dr. Luís F. Ramos.

During this stay, Luis Javier was focused on developing calibration procedures of Finite Elements Models and the integration of dynamical and geomatic approaches in the evaluation of structural damages in constructions.

  • During the first stage, a complete geometrical characterization (trough Terrestrial Laser Scanner) and historical survey were carried out in the Saint Torcato church, with the aim of develop a complete and complex numerical simulation which encloses phase analysis and a complete characterization of the complex mechanical soil behavior.



  • A second stage was focused on the structural evaluation of the prototype Ponta Lumis, with the combination of dynamical and static campaigns. During this stage, a hybrid calibration system was developed, which combined static, dynamic and damage functions in order to improve the numerical simulations.
  • Later, a third stage was focuses on the Digital Image Correlation approach, with the aim of develop mechanical tests Also, geometrical campaigns were carried out on masonry specimens to assist in the development of a new approach, called Tube Jack, with the aim of replacing the traditional Flat Jack test: (http://www.sciencedirect.com/science/article/pii/S0963869513000601).
  • Finally, a geometrical and dynamical analysis was performed in the Keep tower of the Guimarães` Castle. In order to  improve the actual structural knowledge of the construction and also develop geometrical strategies based on NURBs for numerical simulations.










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Análisis termográfico de edificios


El uso de la termografía infrarroja comMapaEnergeticoo técnica sobradamente provada para la inspección de edificios y localización de patologías como fugas de aire, humedades, etc. Nos permite realizar un examen visual “in-situ” de calidad de los objetos de estudio gracias a la posibilidad de visualizar en tiempo real los resultados pudiendo detectar sin dificultad los desperfectos o elementos característicos de estos. Estas técnicas de medición cualitativa nos proporcionan la posibilidad de realizar inspecciones rápidas y eficaces sin contacto directo con el objeto y de forma no destructiva, lo que disminuye tanto el riesgo de incidentes para los operarios como los daños producidos en los propios objetos de estudio ocasionados por otras técnicas intrusivas. Además, también se ha demostrado la utilidad de la termografía infrarroja como técnica puramente de medida a través de su utilización para el cálculo de propiedades termofísicas de materiales tales como difusividad y transmitancia térmica.

En el caso de termografía cualitativa, las publicaciones existentes tratan de estudios realizados in-situ, principalmente en edificios históricos o elementos del patrimonio cultural, mientras que los estudios cualitativos se realizan, en la mayor parte de los casos, en laboratorios sobre muestras de tamaño limitado. En aquellos casos en los que se han realizado estudios termográficos cuantitativos sobre edificios in-situ, los valores de temperatura son empleados con el objetivo de obtener propiedades termofísicas (conductancia térmica) reales del cerramiento, sin embargo su distribución espacial no es considerada.

Conjugar ambas aplicaciones permitirá la automatización del cálculo de pérdidas de calor a partir de las temperaturas medidas con una cámara termográfica. De este modo, no solo se usa la termografía para representar el estado de la pared, sino que también se usan los valores de temperatura contenidos en la termografía para la extracción de parámetros métricos del edificio en estudio, por lo que la hibridación de la información termográfica con el material cartográfico de precisión permitiría extraer la geometría real del objeto de estudio con textura termográfica, pudiendo así realizar mediciones precisas de los elementos de interés directamente sobre el resultado obtenido.




Estudios como el publicado por EuroACE en 2010 colocan la mejora de la eficiencia energética en edificación en cabeza de las acciones necesarias para la reducción de emisiones de gases del efecto invernadero y gasto energético, así como para servir de empuje a la generación de empleo. Especial es el caso del parque de edificios ya construidos, la mayoría procedente de los años 1940-80, con normativa inexistente y recursos escasos. En ellos las obras de rehabilitación energética pueden suponer un ahorro de hasta el 75% en consumo de energía. En España existen 13 millones de viviendas susceptibles de intervención, cuya rehabilitación energética supondría una reducción de las emisiones del sector del 34% con respecto al año 2001.

Building thermographic analysis



The use of infraMapaEnergeticored thermography as a widely tested technique for building inspection and location of pathologies such as air leakage and moisture allows the performance of  quality “in-situ” visual examination of the objects under study due to the possibility of obtaining real-time results, being able to detect without difficulty damages or material characteristics. This qualitative measurement technique provides the capability of doing quick, effective and non-destructive inspection without direct contact with the object under study, decreasing the risk of incidents to operators and the damage of the objects comparing with other intrusive techniques. Furthermore, the utility of infrared thermography as a measurement technique has been proved by its use for the determination of the thermophysical properties of materials such as diffusivity and thermal transmittance.

In the qualitative approach, some authors have performed in-situ studies, mainly in historical buildings or cultural heritage elements, whereas quantitative studies are performed mainly in laboratories with limited size samples. In those cases where quantitative thermography studies were performed in-situ, temperature values were employed in order to obtain the real thermophysical properties (thermal conductance) of the building envelope, but their spatial distribution is not considered.

Combine both applications will enable the automation of the heat loss computation from the measured temperatures with a thermographic camera. Thus, the thermography is not only used to represent the state of the wall, but also temperature values represented on the thermography for extracting the metric parameters of the study object so the hybridization of the thermographic information with precise cartographic material would  allow to extract the actual geometry of the object of study with thermal texture, being able to make accurate measurements of the elements of interest directly on the obtained results.




Studies such as the one published by EuroACE in 2010, places improved energy efficiency in building construction at the top of the list of actions that need to be taken to reduce greenhouse gases and energy costs, in addition to acting as a stimulus to generate employment. In particular is the case of existing buildings stock, most of which dates back to the period 1940-80, constructed using non-existent standards and scarce resources. Here, energy refurbishment works could represent a saving of up to 75% in energy consumption. In Spain there are 13 million homes that could be the subject of intervention, where energy refurbishment could result in a reduction in sector emissions of 34% compared to 2001.


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Ventana modal español
Mobile Laser System (MLS) applied to urban tree inventory

In urbanized Western Europe trees are considered an important component of the built-up environment. This also means that there is an increasing demand for tree inventories. Laser mobile mapping systems provide an efficient and accurate way to sample the 3D road surrounding including notable roadside trees. In this research line, a processing chain aiming at the extraction of tree locations and tree sizes from laser mobile mapping data is reached.

  • Vegetation extraction


  • Tree parameter extraction



Such steps, in combination with code optimization are expected to be sufficient to reach the final goal of automatized estimation of features sampled by mobile mapping at a rate that matches the acquisition speed and at a quality that matches the result of a human operator.