Abstract The extraction of information from point cloud is usually done after the application of classification methods based on the geometric characteristics of the objects. However, the classification of photogrammetric point clouds can be carried out using radiometric information combined with geometric information to minimize possible classification issues. With this in mind, this work proposes an approach to the classification of photogrammetric point cloud, generated by correspondence of aerial images acquired by Remotely Piloted Aircraft System (RPAS). The proposed approach for classifying photogrammetric point clouds consists of a pixel-supervised classification method, based on a decision tree. To achieve this, three data sets were used, one to define which attributes allow discrimination between the classes and the definition of the thresholds. Initially, several attributes were extracted based on a training sample. The average and standard deviation values for the attributes of each class extracted were used to guide the decision tree definition. The defined decision tree was applied to the other two point clouds to validate the approach and for thematic accuracy assessment. The quantitative analyses of the classifications based on kappa coefficient of agreement, applied to both validation areas, reached values higher than 0.938.

Resumo: A classificação é uma importante etapa na extração de primitivas geométricas sobre dados LiDAR. Normalmente, a classificação é utilizada para identificar os pontos amostrados sobre primitivas de interesse. Na literatura são encontrados vários trabalhos que exploram o uso dos autovalores para classificar os pontos LiDAR em diferentes estruturas ou classes, tais como: quina, borda, e plano. Entretanto, alguns trabalhos desenvolvidos se baseiam em parâmetros obtidos a partir de uma geometria ideal, que pode fornecer resultados não adequados quando a amostragem for insuficiente ou quando da presença de ruídos. Para contornar esta limitação, é proposto o uso de métricas estimadas a partir de autovalores e do uso do método k-médias. O conceito de análise de componentes principais é utilizado para determinar os autovalores e algumas métricas derivadas, enquanto que o método k-médias é aplicado para agrupar os pontos de telhados em duas classes: borda e não borda. Para avaliar a metodologia foram selecionadas quatro áreas teste com diferentes níveis de complexidade. A partir dos resultados, foi possível concluir que o procedimento de classificação apresentou resultados satisfatórios, obtendo-se nível de acerto e completeza acima de 92% para os pontos da classe não borda e entre 61% e 98% para a classe borda.

Abstract: The classification is an important step in the extraction of geometric primitives from LiDAR data. Normally, it is applied for the identification of points sampled on geometric primitives of interest. In the literature there are several studies that have explored the use of eigenvalues to classify LiDAR points into different classes or structures, such as corner, edge, and plane. However, in some works the classes are defined considering an ideal geometry, which can be affected by the inadequate sampling and/or by the presence of noise when using real data. To overcome this limitation, in this paper is proposed the use of metrics based on eigenvalues and the k-means method to carry out the classification. So, the concept of principal component analysis is used to obtain the eigenvalues and the derived metrics, while the k-means is applied to cluster the roof points in two classes: edge and non-edge. To evaluate the proposed method four test areas with different levels of complexity were selected. From the qualitative and quantitative analyses, it could be concluded that the proposed classification procedure gave satisfactory results, resulting in completeness and correctness above 92% for the non-edge class, and between 61% to 98% for the edge class.

SUMMARY One of the applications of chitosan is based on its ability to stabilized metallic nanoparticles with minimum chitosan metal molar ratio. This work describes the synthesis and characterization of Ag, Au, Pt, and Cu nanoparticles stabilized by chitosan through chemical reduction of metallic salts by sodium borohydride (NaBH4). The properties of bionanocomposites were studied in terms of their surface plasmon resonance, crystalline structure, average diameter size, particle distributions and functional groups. The samples were characterized by TEM, electron diffraction, UV-Visible and FTIR. The stability of the colloids at room temperature were also measured. A high stability for the colloidal dispersion with chitosan can be observed (> three months). We found that TEM studies show a size distribution between 6 and 10 nm, depending on metals and chitosan metal relation. Electron diffraction analysis for the metallic nanoparticles shows the presence of Ag, Au, Pt and Cu. The FT-IR exhibit the presence of the chitosan in the stabilisation of metallic nanoparticles.

Este artigo apresenta um método que realiza a classificação automática dos pontos amostrados por um sistema de varredura a LASER aerotransportado (SVLA). Nesse método são utilizados os autovalores da matriz de variâncias e covariâncias (MVC). Para o cálculo da MVC considera-se uma vizinhança no entorno do ponto de interesse, a qual é determinada com base no conceito de entropia. A classificação é executada comparando os autovalores calculados, referentes a cada ponto e sua vizinhança, com os autovalores das estruturas ou classes predefinidas. Como medida de similaridade utiliza-se a distância euclidiana no espaço dos autovalores e, com o intuito de eliminar os pontos ambíguos, incorporou-se ao método o fator de não ambiguidade (FNA). Para avaliação do método proposto e implementado, utilizou-se um conjunto de dados LASER referente ao município de Presidente Prudente/SP, cuja densidade aproximada é de 8 pontos/m2. Os resultados mostram que mesmo diante da complexidade dos ambientes reais, algumas estruturas foram bem definidas. Com a incorporação do FNA foi possível identificar e eliminar pontos com alta probabilidade de pertencer a duas classes (pontos ambíguos), geralmente amostrados sobre vegetações, regiões com pequena densidade de pontos, próximos das regiões de bordas e sobre linhas de transmissão próximas as edificações. Por meio da avaliação quantitativa verificou-se que a incorporação do FNA ao método de classificação possibilitou diminuir a quantidade de pontos incorretamente classificados, principalmente para os maiores objetos. Além disso, foi possível verificar que o uso do FNA é interessante para áreas de vegetação, uma vez que grande parte dos pontos ambíguos são identificados.

The aim of this paper is to present a method that automatic performs the classification of 3D points sampled by an airborne LASER scanning system. In this method the eigenvalues of the variance and covariance matrix (MVC) computed for a neighborhood around the points of interest are used to discriminate the predefined classes or structures. This neighborhood is dynamically obtained by using the concept of entropy and the classification is performed by comparing the estimated eigenvalues, relative to each point and its neighborhood, with the eigenvalues of the predefined structures or classes. To compute the similarity, the Euclidean distance in the eigenvalues space was considered and in order to eliminate the ambiguous points the non ambiguity factor (FNA) was incorporated. The evaluation of the proposed and implemented method was realized using a set of LASER data from the city of Presidente Prudente/SP, with an average density of 8 points/m2. The results showed that even with the complexity of real environments, some structures were well defined and can be identified. With the incorporation of FNA it was possible to identify and eliminate points with a high probability of belonging to two (or more) classes (ambiguous points), generally sampled over vegetation, regions with low density points, close to regions of edges and on transmission lines near the buildings. It was also observed that the incorporation of FNA allowed to decrease the number of points incorrectly classified, mainly for big objects. Additionally, it was also possible to verify that the use of FNA is interesting for vegetation areas, since great part of ambiguous points are identified.

Diversos países têm passado por processos de mudança na estrutura geodésica fundamental, convergindo na adoção de referenciais geodésicos geocêntricos. No Brasil, a adoção do SIRGAS2000 envolve a existência conjunta de duas realizações do sistema Córrego Alegre, duas realizações do sistema SAD69 e uma realização do sistema SIRGAS2000. Para o aproveitamento de produtos nos referenciais antigos são necessários métodos para transformação de coordenadas entre os referenciais existentes. Neste contexto, este artigo apresenta uma solução para a transformação de coordenadas entre referenciais, baseado em Thin-Plate Splines (TPS), que reúne características para a modelagem de dados provenientes de uma transformação linear, juntamente com distorções de natureza não linear. O modelo foi desenvolvido para trabalhar com coordenadas cartesianas tridimensionais, sendo apresentados neste artigo resultados com dados simulados bem como com dados do SGB (Sistema Geodésico Brasileiro). Em pontos de verificação em SAD69 (realização de 1996 - SAD69/96) foram obtidos valores de RMSE (Root Mean Square Error) de 78,2 mm em latitude e 67,5 mm em longitude após a transformação para SIRGAS2000. Na comparação entre o modelo TPS e o proporcionado pelo ProGriD os indicadores estatísticos foram reduzidos em 97% ao utilizar o modelo TPS, indicando que o uso deste modelo é promissor, possibilitando uma maior qualidade no processo de transformação de coordenadas e modelagem da distorção entre referenciais geodésicos.

Several countries have been passed by change processes in their fundamental geodesic structure with the focus on the adoption of geocentric reference systems. In Brazil, the adoption of the SIRGAS2000 evolves the coexistence of two realizations from the Córrego Alegre system, two realizations from the SAD69 system and one realization from the SIRGAS2000 system. To make use of products in the old reference systems, methods of coordinate transformation between the existent reference frames are necessary. So, in this paper one solution for the transformation between coordinates from different reference frames, based on Thin-Plate Splines (TPS), that allows the estimation of parameters from one linear transformation and also one non-linear model is presented. The TPS model was developed to work with tridimensional coordinates and in this paper the results and analysis are performed with simulated data and also with data from the official Brazilian Geodetic System (SGB). In the check points from SAD69 stations (realization of 1996 - SAD69/96), the values of RMSE obtained were of 78,2 mm in latitude and 67,5 mm in longitude, before the transformation to the SIRGAS2000. In the comparison between the TPS model and ProGriD (Brazilian software provided by IBGE), the statistical indicators were reduced in 97%, by using the TPS model. Based in the obtained results from real dataset, the TPS model appears to be promising, since it allows improving the quality of transformation process with simultaneous distortion modeling.

O objetivo deste trabalho foi avaliar o efeito de diferentes crioprotetores na viabilidade de embriões de dourado (Salminus brasiliensis). Foram testadas dez soluções crioprotetoras. Para cada solução, 300 embriões foram selecionados na fase do fechamento do blastóporo, e mais 300 embriões foram utilizados como controle negativo. Após o resfriamento (-8ºC por 6 horas), os embriões foram reidratados diretamente na incubadora até a eclosão. O melhor resultado é obtido com solução crioprotetora com 9% de metanol associado a 17% de sacarose, o que resultou em taxa de eclosão de larvas de 67,06%.

The objective of this work was to evaluate the effect of different cryoprotectants on the viability of dourado (Salminus brasiliensis) embryos. Ten cryoprotectant solutions were tested. For each solution, 300 embryos were selected at the closing of the blastopore stage, and 300 more embryos were used as a negative control. After cooling (-8ºC for 6 hours), the embryos were rehydrated directly in the incubator until hatching. The best result is obtained with the cryoprotectant solution containing 9% methanol associated with 17% sucrose, resulting in a larvae hatching rate of 67.06%.

The spectroelectrochemical properties of a conducting polymer derived from Co(II) tetra-3-amino-phenyl-porphyrin,(poly-Co(II)-TAPP) were studied towards the electrochemical reduction of CO2 on ITO surface. Under inert atmosphere, the results show that the polymer present a stable Co(I) oxidation state only in basic pH while in more acidic solution this Co(I) does not stabilize. Under CO2 atmosphere the reduced polymer forms a stable adduct with no clear electronic localization. The formation and the stability of this adduct could explain the wide distribution of reaction products

The aim of this work was the study of three different modified electrodes where the substrate and the porphyrin used to modify the electrodic surface was the same. The surface electrode was a glass covered by a layer of SnO2 doped with fluor. On this layer was formed a cubic spinel of Co-cobaltite. On this modified electrode was deposited or polymerized para-tetraaminophenylporphyrin of Ni (II). In each case, the treatment of the deposition of the porphyrin was different and the electrocatalytic behavior of the modified electrodes toward the oxidation of hydrazine drastically changes. In the case of a simple physically adsorbed layer of porphyrin, practically no electrocatalytic activity was found. In the case of a porphyrin deposited by reflux and cycled in basic solution, there is an important electrocatalytic activity giving N2 as product. This electrode was proved as an amperometric sensor of hydrazine and a very good linear relationship between current and concentration was determinate. Also, the polymeric electrode showed an important catalytic behavior toward the oxidation of hydrazine

In this paper we present a simple and mild procedure to incorporate cations of transition metals to a polymer of the free-ligand para-tetraaminophenylporphyrin (H2TAPP) in order to obtain similar responses as in the case of the direct electropolymerization of a metallic complex. Sometimes, it is not possible to obtain an electropolymerized complex under a determined set of conditions. Changes in the conditions of synthesis drastically alter the properties of the polymers and, thus, the modification of the parameters of synthesis is not a feasible method to obtain a desired polymer. In those cases, a polymer of the free-ligand can be obtained and then the metallic ions can be incorporated so that an identical polymer to the one that could be obtained from the direct polymerization of the complex is obtained.