Miguel Castro-García

Alternative methods for teaching cadastre and remote sensing

Cadastre is essential for the sustainable development of modern society. As well, mapping and surveying is one of the most important tasks for surveyors worldwide in order to maintain the Cadastre. This article summarises a recent study conducted by the authors on overall student assessment of learning Cadastre and Remote Sensing. The goal is to highlight which teaching method has better success rate for students. This paper studies the academic outcomes for a total of 286 students divided into two optional courses of Cadastre at higher education for eight academic years. They are analysed through three different educational modalities: face-to-face (FTF), blended and online for one course, and FTF and online for another. In order to deepen the analysis, a model using classification trees (Classification and regression trees, CART) was created. It has been observed that the blended modality is the one that offers worst results in terms of success rate. If we compare exclusively the FTF method to the online one, we can conclude that the latter shows better results in all respects, improving the success rate and increasing the percentage of students who obtain highest marks.

Radiomics of CT Features May Be Nonreproducible and Redundant: Influence of CT Acquisition Parameters

Purpose To identify the reproducible and nonredundant radiomics features (RFs) for computed tomography (CT). Materials and Methods Two phantoms were used to test RF reproducibility by using test-retest analysis, by changing the CT acquisition parameters (hereafter, intra-CT analysis), and by comparing five different scanners with the same CT parameters (hereafter, inter-CT analysis). Reproducible RFs were selected by using the concordance correlation coefficient (as a measure of the agreement between variables) and the coefficient of variation (defined as the ratio of the standard deviation to the mean). Redundant features were grouped by using hierarchical cluster analysis. Results A total of 177 RFs including intensity, shape, and texture features were evaluated. The test-retest analysis showed that 91% (161 of 177) of the RFs were reproducible according to concordance correlation coefficient. Reproducibility of intra-CT RFs, based on coefficient of variation, ranged from 89.3% (151 of 177) to 43.1% (76 of 177) where the pitch factor and the reconstruction kernel were modified, respectively. Reproducibility of inter-CT RFs, based on coefficient of variation, also showed large material differences, from 85.3% (151 of 177; wood) to only 15.8% (28 of 177; polyurethane). Ten clusters were identified after the hierarchical cluster analysis and one RF per cluster was chosen as representative. Conclusion Many RFs were redundant and nonreproducible. If all the CT parameters are fixed except field of view, tube voltage, and milliamperage, then the information provided by the analyzed RFs can be summarized in only 10 RFs (each representing a cluster) because of redundancy.

Learning effectiveness of virtual environments for 3D terrain interpretation and data acquisition

The aim of this study is to assess the effectiveness of different learning strategies for 3D terrain interpretation and data acquisition by engineering students. According to the experimental design, students received homogeneous training, followed by differential training, which divided the students into three statistically homogeneous groups where each group was subject to a different learning process: (1) virtual environment learning; (2) learning using physical scale models; and (3) a theoretical class. Afterwards, the students were evaluated using two tests under real field conditions. Results were obtained for the following study variables: field-test scores and whether or not the student was repeating the course. The students who learned using physical scale models obtained the best scores; their scores were significantly higher than those of students using virtual environment or a theoretical class. These findings open up new perspectives on the teaching of surveying with respect to other teaching methods.

A hemispherical contact model for simplifying 3D occlusal surfaces

Statement of problem. Currently, dental articulators can recreate mandibular movements and occlusal contacts. However, whether virtual articulators can also provide information about occluding dental surfaces, functional movements, and the mandibular condyles is unclear. Purpose. The purpose of this in vitro study was to evaluate the occluding surfaces on dental casts obtained from a patient and approximate them to a hemispherical contact model. Both models were tested by digitizing the Dentatus ARL dental articulator. Material and methods. A combination of photogrammetry and structure from motion methods were used to scan a Dentatus ARL articulator and representative dental casts. Using computer‐aided engineering and finite element analysis, contact points and action vectors to the forces on occluding surfaces and condyles were obtained for cast and hemispherical models. This experiment was performed using centric occlusion and 3 different condylar inclinations. The Kruskal‐Wallis 1‐way analysis of variance on ranks test was used to allow all pairwise comparisons between condylar inclination and mechanical action vector values in each location (&agr;=.05). Results. Action vectors from the cast model and each location of the hemispherical model were calculated to show the mechanical consequences and the similarity among models. Overall, no significant differences were observed for action vectors (A20 versus A40 versus A60) at each location (dental cast/hemisphere, right condylar, and left condylar) in the analysis of dental casts and the hemisphere model (.382≤P≤.999). Conclusions. This study provided graphical information that may assist the dental professional in determining which occlusal contacts should be modified to attain condylar and balanced centric occlusion.

Developing Topographic Surveying Software to Train Civil Engineers

AbstractIn this study, software was developed for the improvement of professional skills in topographic-surveying subjects taught in engineering degree programs. This learning tool is focused on developing the skill involved in virtual rod reading through the telescope of topographic equipment, attempting to completely substitute a traditional practical class (laboratory and field work). For assessment of the developed tool, two experimental student units were created by a process of homogenization of knowledge and later subdivided into groups. The first experimental unit was trained traditionally in handling topographic equipment. The second unit was trained virtually with the developed software. Results obtained for each group showed a high level of learning and revealed characteristics that differentiate the acquired professional skills. Because the effectiveness of reaching pedagogical goals with virtual training was demonstrated, it was concluded that the developed software could be substituted for f...