Generación de mapas digitales de vegetación a nivel de parcela mediante la utilización de un escáner láser terrestre (LIDAR)

El present projecte final de carrera s'engloba dins de l'àmbit de l'Agricultura de Precisió (AP). La qual es presenta com una resposta als nous condicionants i reptes existents que giren entorn a l'agricultura, entre el quals caldria citar: la seguretat, el respecte del medi ambient, la qualitat i l'augment de la competitivitat dins del sector agrícola. Per tant, per fer front davant d'aquest escenari, cal plantejar-se una nova manera d'entendre l'agricultura. El principal fonament de la AP es basa en la necessitat de dur a terme totes les accions agrícoles tenint en compte la variabilitat inherent que existeix a les parcel·les. Doncs bé, el present treball es realitza en una plantació de vinya. Concretament s'utilitza una tecnologia làser capaç de caracteritzar la vegetació del cultiu i posteriorment, mitjançant l'ús d'eines matemàtiques, s'arriba a la generació de mapes de vegetació juntament amb la creació de diferents zones de maneig. Per tant, el resultat d'aquest treball és posar a disposició de l'agricultura una metodologia capaç de generar mapes de vegetació, que serviran de base per a l'aplicació dels diferents insums, tenint en compte la variabilitat intraparcelària.

Bioinspired electronic white cane implementation based on a LIDAR, a tri-axial accelerometer and a tactile belt

This work proposes the creation of a bioinspired electronic white cane for blind people using the whiskers principle for short-range navigation and exploration. Whiskers are coarse hairs of an animal's face that tells the animal that it has touched something using the nerves of the skin. In this work the raw data acquired from a low-size terrestrial LIDAR and a tri-axial accelerometer is converted into tactile information using several electromagnetic devices configured as a tactile belt. The LIDAR and the accelerometer are attached to the user’s forearm and connected with a wire to the control unit placed on the belt. Early validation experiments carried out in the laboratory are promising in terms of usability and description of the environment.

Characterisation of the LMS200 laser beam under the influence of blockage surfaces. Influence on 3D scanning of tree orchards

The geometric characterisation of tree orchards is a high-precision activity comprising the accurate measurement and knowledge of the geometry and structure of the trees. Different types of sensors can be used to perform this characterisation. In this work a terrestrial LIDAR sensor (SICK LMS200) whose emission source was a 905-nm pulsed laser diode was used. Given the known dimensions of the laser beam cross-section (with diameters ranging from 12 mm at the point of emission to 47.2 mm at a distance of 8 m), and the known dimensions of the elements that make up the crops under study (flowers, leaves, fruits, branches, trunks), it was anticipated that, for much of the time, the laser beam would only partially hit a foreground target/object, with the consequent problem of mixed pixels or edge effects. Understanding what happens in such situations was the principal objective of this work. With this in mind, a series of tests were set up to determine the geometry of the emitted beam and to determine the response of the sensor to different beam blockage scenarios. The main conclusions that were drawn from the results obtained were: (i) in a partial beam blockage scenario, the distance value given by the sensor depends more on the blocked radiant power than on the blocked surface area; (ii) there is an area that influences the measurements obtained that is dependent on the percentage of blockage and which ranges from 1.5 to 2.5 m with respect to the foreground target/object. If the laser beam impacts on a second target/object located within this range, this will affect the measurement given by the sensor. To interpret the information obtained from the point clouds provided by the LIDAR sensors, such as the volume occupied and the enclosing area, it is necessary to know the resolution and the process for obtaining this mesh of points and also to be aware of the problem associated with mixed pixels.

Innovative LIDAR 3D dynamic measurement system to estimate fruit-tree leaf area

In this work, a LIDAR-based 3D Dynamic Measurement System is presented and evaluated for the geometric characterization of tree crops. Using this measurement system, trees were scanned from two opposing sides to obtain two three-dimensional point clouds. After registration of the point clouds, a simple and easily obtainable parameter is the number of impacts received by the scanned vegetation. The work in this study is based on the hypothesis of the existence of a linear relationship between the number of impacts of the LIDAR sensor laser beam on the vegetation and the tree leaf area. Tests performed under laboratory conditions using an ornamental tree and, subsequently, in a pear tree orchard demonstrate the correct operation of the measurement system presented in this paper. The results from both the laboratory and field tests confirm the initial hypothesis and the 3D Dynamic Measurement System is validated in field operation. This opens the door to new lines of research centred on the geometric characterization of tree crops in the field of agriculture and, more specifically, in precision fruit growing.

Ultrasonic and LIDAR sensors for electronic canopy characterization in vineyards: advances to improve pesticide application methods

Canopy characterization is a key factor to improve pesticide application methods in tree crops and vineyards. Development of quick, easy and efficient methods to determine the fundamental parameters used to characterize canopy structure is thus an important need. In this research the use of ultrasonic and LIDAR sensors have been compared with the traditional manual and destructive canopy measurement procedure. For both methods the values of key parameters such as crop height, crop width, crop volume or leaf area have been compared. Obtained results indicate that an ultrasonic sensor is an appropriate tool to determine the average canopy characteristics, while a LIDAR sensor provides more accuracy and detailed information about the canopy. Good correlations have been obtained between crop volume (CVU) values measured with ultrasonic sensors and leaf area index, LAI (R2 = 0.51). A good correlation has also been obtained between the canopy volume measured with ultrasonic and LIDAR sensors (R2 = 0.52). Laser measurements of crop height (CHL) allow one to accurately predict the canopy volume. The proposed new technologies seems very appropriate as complementary tools to improve the efficiency of pesticide applications, although further improvements are still needed.

Measuring oscillating walking paths with a LIDAR

This work describes the analysis of different walking paths registered using a Light Detection And Ranging (LIDAR) laser range sensor in order to measure oscillating trajectories during unsupervised walking. The estimate of the gait and trajectory parameters were obtained with a terrestrial LIDAR placed 100 mm above the ground with the scanning plane parallel to the floor to measure the trajectory of the legs without attaching any markers or modifying the floor. Three different large walking experiments were performed to test the proposed measurement system with straight and oscillating trajectories. The main advantages of the proposed system are the possibility to measure several steps and obtain average gait parameters and the minimum infrastructure required. This measurement system enables the development of new ambulatory applications based on the analysis of the gait and the trajectory during a walk.

Discriminating crop, weeds and soil surface with a terrestrial LIDAR sensor

In this study, the evaluation of the accuracy and performance of a light detection and ranging (LIDAR) sensor for vegetation using distance and reflection measurements aiming to detect and discriminate maize plants and weeds from soil surface was done. The study continues a previous work carried out in a maize field in Spain with a LIDAR sensor using exclusively one index, the height profile. The current system uses a combination of the two mentioned indexes. The experiment was carried out in a maize field at growth stage 12–14, at 16 different locations selected to represent the widest possible density of three weeds: Echinochloa crus-galli (L.) P.Beauv., Lamium purpureum L., Galium aparine L.and Veronica persica Poir.. A terrestrial LIDAR sensor was mounted on a tripod pointing to the inter-row area, with its horizontal axis and the field of view pointing vertically downwards to the ground, scanning a vertical plane with the potential presence of vegetation. Immediately after the LIDAR data acquisition (distances and reflection measurements), actual heights of plants were estimated using an appropriate methodology. For that purpose, digital images were taken of each sampled area. Data showed a high correlation between LIDAR measured height and actual plant heights (R2 = 0.75). Binary logistic regression between weed presence/absence and the sensor readings (LIDAR height and reflection values) was used to validate the accuracy of the sensor. This permitted the discrimination of vegetation from the ground with an accuracy of up to 95%. In addition, a Canonical Discrimination Analysis (CDA) was able to discriminate mostly between soil and vegetation and, to a far lesser extent, between crop and weeds. The studied methodology arises as a good system for weed detection, which in combination with other principles, such as vision-based technologies, could improve the efficiency and accuracy of herbicide spraying.

Interferometría SAR en las islas Shetlend del Sur: modelo numérico de elevaciones de la Isla Decepción

La interferometría con imágenes de radar de apertura sintética (SAR: Synthetic Aperture Radar) desde satélite es una técnica que permite obtener información altimétrica del relieve terrestre, siendo especialmente útil en áreas remotas. Este trabajo muestra una aplicación de esta técnica en las islas Shetland del Sur (Antártida). Para ello se han utilizado imágenes SAR obtenidas por los satélites ERS (European Remote Sensing) de la Agencia Espacial Europea (ESA: European Space Agency) y un proceso interferométrico desarrollado entre el Departament de Geodinàmica i Geofísica de la Universitat de Barcelona y el Institut Cartogràfic de Catalunya.

Sistema de visualización SIG del Servei Meteorològic de Catalunya

El sistema de visualización SIG del Servei Meteorològic de Catalunya (SMC) consiste en un sistema que visualiza la información meteorológica del SMC mediante un visor SIG. La herramienta permitirá a los técnicos del SMC poder consultar productos meteorológicos, como modelos numéricos, productos de Meteosat, radar, descargas eléctricas, etc. El sistema se compone de un servidor MapServer, utilizando MapCache como sistema de caché, y de un visor SIG web implementado en JavaScript, utilizando las librerías Dojo Toolkit y OpenLayers.

Archaeological Excavation Confirms the Geophysical Anomalies Recorded at the Cathedral of Tarragona - A Comparative Study

An integrated geophysical survey was conducted in September 2007 at the Cathedral of Tarragona (Catalonia, NE Spain), to search for archaeological remains of the Roman temple dedicated to the Emperor Augustus. Many hypotheses about its location have been put forward, the most recent ones suggesting it could be inside the present cathedral. Tarragona’s Cathedral, one of the most famous churches in Spain (12th century), was built during the evolution from the Romanesque to Gothic styles. As its area is rather wide, direct digging to detect hidden structures would be expensive and also interfere with religious services. Consequently, the use of detailed non-invasive analyses was preferred. A project including Electrical resistivity tomography (ERT) and Ground probing radar (GPR) was planned for a year and conducted during a week of intensive field survey. Both ERT and GPR provided detailed information about subsoil structures. Different ERT techniques and arrays were used, ranging from standard Wenner-Schlumberger 2D sections to full 3D electrical imaging using the MYG array. Electrical resistivity data were recorded extensively, making available many thousands of apparent resistivity points to obtain a complete 3D image after full inversion. The geophysical results were clear enough to persuade the archaeologists to excavate the area. The excavation confirmed the geophysical interpretation. In conclusion, the significant buried structures revealed by geophysical methods under the cathedral were confirmed by recent archaeological digging as the basement of the impressive Roman Temple that headed the Provincial Forum of Tarraco, seat of the Concilium of Hispania Citerior Province.