Building Information Models (BIM) are becoming a standard in the construction indus- try for storing information about buildings and assets. Automatically creating BIMs has attracted a lot of attention, as it has great potential to improve efficient resource man- agement. A detailed description of the building can decrease the cost of management, heating and cooling, and restoration. For pre-existing structures design documents are typically outdated or unavailable, making BIMs challenging to acquire. The field of indoor floor plan creation has grown in recent years due to advancements in LIDAR technology. However, LIDARs create millions of points per scan, making it computationally expensive to process all of them. In order to properly create a floor it is imperative to acquire a sufficient number of scans to visualize the whole building, while simultaneously minimizing the number of scans for computational reasons. We propose a method for selecting a subset of the scans, as well as a method for clustering points into lines to be used for floor plan extraction. Our method works by clustering nearby points, creating a convex hull around them, and selecting scans based on the most area covered by the union of the hulls. The point clustering splits the pointcloud into potential lines by projecting each point along its surface normal, clustering points from the same line together. Those improvements allow for the efficient generation of floor plans for large buildings. / Thesis / Master of Science (MSc)

Ce mémoire présente une analyse des performances d'algorithmes de pistage dans le cas d'un lidar à faible résolution angulaire. Plus particulièrement, on s'intéresse à un système lidar composé de capteurs individuels couvrant chacun une région angulaire distincte. Les capteurs utilisés ont la particularité de mesurer uniquement la distance des objets rencontrés, limitant ainsi la résolution angulaire à leur faisceau. Les algorithmes ont été testés à l'aide de données de simulations basées sur le système lidar. Dans les cas de détections simples, un algorithme de pistage instantané basé sur un filtre de Kalman a été amplement suffisant. Pour des cas plus complexes, l'utilisation de la théorie des hypothèses multiples ( MHT pour multiple hypothesis theory ) a permis d'améliorer les résultats d'associations. Dans cette méthode, lorsqu'il y a une ambiguïté d'associations, les hypothèses probables sont considérées en parallèle jusqu'à ce que l'information reçue aux instants subséquents permette d'identifier l'association la plus probable. Pour le cas à l'étude, les résultats optimaux ont été obtenus pour un MHT considérant au plus 3 hypothèses à chaque instant et en attendant au plus 3 pas de temps pour prendre une décision. Globalement, les algorithmes présentés ont mieux réagi face aux fausses alarmes plutôt que face aux non détections. Une méthode permettant d'optimiser les temps de calcul des algorithmes a également été développée. Cette méthode se base sur l'algorithme de Murty et permet de passer d'une méthode d'association simple et rapide (ici l'algorithme d'associations par plus proches voisins)à une méthode d'associations plus complexe (ici par filtre de Kalman) seulement lorsqu'une ambiguïté est détectée dans l'association. Dans le cas d'une situation simple à deux cibles, des performances comparables à celle d'une association par filtre de Kalman ont été obtenues avec un temps de calcul de moins de 10% de celui nécessaire habituellement. / This thesis presents an analysis of the performance of tracking algorithms in the case of a lidar with low angular resolution. More particularly, we are interested in a lidar system composed of individual sensors each covering a distinct angular region. The sensors used have the particularity of measuring only the distance of the objects encountered, thus limiting the angular resolution to their beam. The algorithms were tested using simulation data based on the lidar system. In the case of simple detections, an instant tracking algorithm based on a Kalman filter was more than sufficient. For more complex cases, the use of multiple hypothesis theory (MHT) made it possible to improve tracking results. In this method, when there is an ambiguity in the tracking, the possible hypotheses are considered simultaneously until the information received at subsequent times makes it possible to identify the correct one. For the case under study, optimal results were obtained for an MHT considering at most 3 hypotheses at any time and waiting at most 3 time steps to make a decision. Overall, the algorithms presented reacted better to false alarms rather than to non-detections. A method for optimizing the calculation times of the algorithms has also been developed. This method is based on Murty's algorithm goes from a simple and fast tracking method (here by nearest neighbors) to a more complex association method (here using a Kalman lter) only when an ambiguity is detected. In the case of a simple situation with two targets, performances comparable to that of an association by Kalman filter were obtained with a calculation time of less than 10% of that usually required.

Les pratiques d'aménagement forestier doivent être adaptées aux particularités des écosystèmes. L'inventaire de la structure forestière permet de fournir les informations de base pour décrire la diversité des écosystèmes. La télédétection est une solution économique pour mesurer de manière détaillée et extensive la structure forestière. Le lidar (Light Detection and Ranging) aéroporté est une technologie qui permet d'observer la structure tridimensionnelle de la végétation sur de grandes superficies. Cette thèse s'intéresse à trois éléments de la structure forestière : l'âge, la composition et la densité de couvert. Dans le premier chapitre, nous utilisons la distribution verticale des retours lidar ainsi que d'autres indicateurs de structure forestière (hauteur, taux de pénétration des premiers retours, paramètres de distribution Weibull) et de station (altitude, pente, orientation, radiation solaire, indice d'humidité, aire du bassin versant et longueur de pente arrière) pour prédire l'âge moyen des placettes avec une erreur de prédiction de 8.8 ans (R² 0.83, racine de l'erreur quadratique moyenne (RMSE) 19%). Dans le deuxième chapitre, nous avons associé la distribution verticale des retours lidar à l'espèce, l'âge et la densité de couvert en utilisant un GLM fonctionnel et un nouveau test de signifiance non paramétrique graphique permettant d'identifier les variations associées à chacune des variables. Nos résultats indiquent que les trois variables peuvent expliquer jusqu'à 47% de la variation de la distribution verticale des retours lidar. Chaque espèce présentait des caractéristiques discriminantes, mais trois groupes se démarquaient : les peuplements de peuplier faux-tremble affichaient la distribution verticale la plus uniforme ; les peuplements de sapin baumier et de bouleau à papier présentaient une distribution centrée autour de 50% de la hauteur. Les peuplements dominés par les épinettes blanche et noire présentaient une distribution plutôt concentrée à 30% de la hauteur du peuplement. Une augmentation de la fermeture du couvert était associée à une concentration de la distribution autour de 50% de la hauteur du peuplement. L'augmentation de l'âge déplaçait la distribution dans la partie supérieure du peuplement jusqu'à 50-70 ans, puis se stabilisait et redescendait à 90-120 ans. Finalement, nous avons étudié l'influence du seuil de hauteur et de la résolution spatiale de la grille sur la répétabilité des mesures de densité de couvert par lidar aéroporté en utilisant trois survols, dont deux conduits la même année (respectivement 2016 et 2018). En utilisant une mesure d'asymétrie (skewness) et la variance des différences décalées de la densité de couvert, nous avons identifié des mesures qui étaient plus répétables entre les survols. Les résultats montrent que les paramètres suivants étaient optimaux : seuil de hauteur à 3 m, résolution de grille de 25 m (RMSE de 7% et 5% ; biais de 4% et 0% pour les relevés à basse densité de 2016 et 2018). Ces résultats montrent que le lidar est un outil important pour l'enrichissement des données d'inventaire par des données de structure et pourrait contribuer à cibler les pratiques d'aménagement adaptées aux particularités des écosystèmes.

Ce mémoire présente une analyse des performances d'algorithmes de pistage dans le cas d'un lidar à faible résolution angulaire. Plus particulièrement, on s'intéresse à un système lidar composé de capteurs individuels couvrant chacun une région angulaire distincte. Les capteurs utilisés ont la particularité de mesurer uniquement la distance des objets rencontrés, limitant ainsi la résolution angulaire à leur faisceau. Les algorithmes ont été testés à l'aide de données de simulations basées sur le système lidar. Dans les cas de détections simples, un algorithme de pistage instantané basé sur un filtre de Kalman a été amplement suffisant. Pour des cas plus complexes, l'utilisation de la théorie des hypothèses multiples ( MHT pour multiple hypothesis theory ) a permis d'améliorer les résultats d'associations. Dans cette méthode, lorsqu'il y a une ambiguïté d'associations, les hypothèses probables sont considérées en parallèle jusqu'à ce que l'information reçue aux instants subséquents permette d'identifier l'association la plus probable. Pour le cas à l'étude, les résultats optimaux ont été obtenus pour un MHT considérant au plus 3 hypothèses à chaque instant et en attendant au plus 3 pas de temps pour prendre une décision. Globalement, les algorithmes présentés ont mieux réagi face aux fausses alarmes plutôt que face aux non détections. Une méthode permettant d'optimiser les temps de calcul des algorithmes a également été développée. Cette méthode se base sur l'algorithme de Murty et permet de passer d'une méthode d'association simple et rapide (ici l'algorithme d'associations par plus proches voisins)à une méthode d'associations plus complexe (ici par filtre de Kalman) seulement lorsqu'une ambiguïté est détectée dans l'association. Dans le cas d'une situation simple à deux cibles, des performances comparables à celle d'une association par filtre de Kalman ont été obtenues avec un temps de calcul de moins de 10% de celui nécessaire habituellement. / This thesis presents an analysis of the performance of tracking algorithms in the case of a lidar with low angular resolution. More particularly, we are interested in a lidar system composed of individual sensors each covering a distinct angular region. The sensors used have the particularity of measuring only the distance of the objects encountered, thus limiting the angular resolution to their beam. The algorithms were tested using simulation data based on the lidar system. In the case of simple detections, an instant tracking algorithm based on a Kalman filter was more than sufficient. For more complex cases, the use of multiple hypothesis theory (MHT) made it possible to improve tracking results. In this method, when there is an ambiguity in the tracking, the possible hypotheses are considered simultaneously until the information received at subsequent times makes it possible to identify the correct one. For the case under study, optimal results were obtained for an MHT considering at most 3 hypotheses at any time and waiting at most 3 time steps to make a decision. Overall, the algorithms presented reacted better to false alarms rather than to non-detections. A method for optimizing the calculation times of the algorithms has also been developed. This method is based on Murty's algorithm goes from a simple and fast tracking method (here by nearest neighbors) to a more complex association method (here using a Kalman lter) only when an ambiguity is detected. In the case of a simple situation with two targets, performances comparable to that of an association by Kalman filter were obtained with a calculation time of less than 10% of that usually required.

Le balayage lidar aéroporté permet la production de modèles numériques de terrain (MNT) précis et à haute résolution. Cette thèse fait partie d'un projet où le DTM est utilisé pour évaluer la hauteur d'eau en crue et estimer le risque qu'elle atteigne les ouvertures inférieures des bâtiments. Ce travail est fait pour aider les décideurs à évaluer les dommages causés par les inondations. Cependant, le DTM est souvent présenté sans estimation de sa précision. La comparaison avec la vérité terrain est une approche courante pour estimer la qualité du DTM. Alors que la fiabilité d'une telle approche dépend de divers facteurs dont la taille de l'échantillon, l'accessibilité sur le terrain, la distribution et une assez grande diversité de vérité terrain, ce qui a un coût et est quelque peu irréalisable à l'échelle de la province de Québec. Par conséquent, l'objectif principal de cette recherche est de concevoir une méthode qui pourrait fournir une estimation locale de l'erreur sans aucune dépendance à des ensembles de données tiers. À cet égard, nous profitons du krigeage géostatistique comme estimateur alternatif de la qualité. Le défi de considérer une variation constante dans l'espace nous amène à proposer une méthode non stationnaire qui aboutit à l'estimation locale de l'erreur d'élévation du MNT. La performance de la méthode présentée a été validée par la comparaison avec l'évaluation de la vérité terrain. Les résultats ont révélé que notre méthode est fiable dans les zones urbaines et semi-urbaines, en particulier dans les zones agricoles et résidentielles sauf dans les forêts qui sont dues à leur plus faible densité. / Airborne lidar scanning allows the production of accurate and high-resolution digital terrain models (DTM). This thesis is part of a project where the DTM is used to assess the water height in flood and estimate the risk it reaches the lower openings in buildings. This work is done to support decision-makers in estimating damages caused by floods. However, DTM is often presented without an estimation of its accuracy. Comparison with ground truth is a common approach to estimating the quality of DTM. Whereas the reliability of such an approach depends on various factors including sample size, accessibility on the field, distribution, and a large enough diversity of ground truth, which comes at a cost and is somewhat unfeasible in the scale of Quebec province. Therefore, the main objective of this research is to design a method that could provide a local estimation of error without any dependency on third-party datasets. In this regard, we take advantage of geostatistical kriging as an alternative quality estimator. The challenge of considering constant variation across the space brings us to propose a non-stationary method that results in the local estimation of DTM elevation error. The performance of the presented method was validated with the comparison with ground truth assessment. The results revealed that our method is reliable in urban and semi-urban areas, especially in farmland and residential areas except in forests which are due to their lowest density.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Os aerossóis e nuvens desenvolvem um papel muito importante nos processos climáticos terrestres por meio das suas contribuições diretas e indiretas no balanço radiativo da atmosfera. A dificuldade na previsão dos processos de mudanças climáticas estão associadas às incertezas na distribuição e propriedades dos aerossóis e nuvens, assim como em suas interações em escala global. Tendo como principal objetivo desenvolver estudos que ajudem na diminuição dessas incertezas, a NASA, em parceria com a agência espacial francesa CNES, desenvolveu a missão do Satélite CALIPSO, que possui a bordo um sistema Lidar denominado CALIOP capaz de estudar o perfil e a distribuição vertical dos aerossóis e nuvens e os processos de interação entre eles. Uma vez que as propriedade ópticas medidas pelo CALIOP são recuperadas utilizando um complexo conjunto de algoritmos, torna-se necessário o desenvolvimento de estudos e metodologias de validação para inferir qual a acurácia das medidas desse sistema. Nesse contexto, foi desenvolvida uma metodologia de avaliação e validação dos valores de Razão Lidar utilizados a priori pelos algoritmos do CALIOP utilizando dois instrumentos de sensoriamento remoto instalados em solo, um sistema Lidar de retroespalhamento elástico instalado no IPEN - São Paulo e o fotômetro solar da rede AERONET instalado em cinco diferentes localidades, Rio Branco - Acre (RB), Alta Floresta - Mato Grosso (AF), Cuiabá - Mato Grosso (CB), Campo Grande - Mato Grosso do Sul (CG) e São Paulo - São Paulo (SP). Foram determinados os dias de medidas correlativas entre os sistemas em solo e o CALIOP e analisados os dados para os dias de medidas com condições livre de nuvens e com trajetórias de massas de ar se deslocando das regiões de medidas do satélite para as regiões de medidas pelos instrumentos fixos. Foram calculados novos valores de Razão Lidar obtidos pelo Modelo Aeronet/Caliop (Modelo A/C) proposto. Esses valores mostraram-se coerentes com aqueles utilizados inicialmente pelo algoritmo do sistema CALIOP. Realizando uma comparação quantitativa, obteve-se uma diferença percentual de 2,17 ± 30,12%, esse valor mostra-se compatível com outros valores obtidos na literatura de validação desse sistema Lidar a bordo do Satélite CALIPSO. Essa subestimação nos valores de Razão Lidar utilizados pelo CALIOP pode estar ocorrendo devido um problema no processo de calibração dos dados do sistema CALIOP, uma vez que o território brasileiro se encontra na região da Anomalia do Atlântico Sul (SAA). A diferença percentual dos valores de Razão Lidar utilizados pelo CALIOP com aqueles obtido por meio de medidas com o sistema Lidar do IPEN forneceram valores de 2,34 ± 17,53%, demonstrando que o modelo de validação proposto é aceitável e acurácia nos valores de Razão Lidar utilizados a priori pelo CALIOP está dentro das margens de incerteza de 30%. / Aerosol and clouds play an important role in the Earths climate process through their direct and indirect contributions to the radiation budget. The largest difficulty in predicting the climate change processes is associated with uncertainties in the distribution and properties of aerosols and clouds, as well as their interactions on a global scale. The CALIPSO mission was developed as part of the NASA program, in collaboration with the French space agency CNES, with the main goal to develop studies that will help to quantify the uncertainties about aerosols and clouds. The CALIPSO satellite carried a Lidar system on board, named CALIOP, as a primary instrument, able to provide the aerosol and cloud vertical profiles and distribution, as well as their interactions. Once the optical properties measured by CALIOP are retrieved, using a complex set of algorithms, it is necessary to study and develop methodologies in order to assess the accuracy of the CALIOP products. In this context, a validation methodology was developed in order to verify the assumed values of the Lidar Ratio selected by the CALIOP algorithms, using two ground-based remote sensing instruments, an elastic backscatter Lidar system (MSP) installed at IPEN in São Paulo and the AERONET sunphotometers operating at five different locations in Brazil, Rio Branco - Acre (RB), Alta Floresta - Mato Grosso (AF), Cuiabá - Mato Grosso (CB), Campo Grande - Mato Grosso do Sul (CG) e São Paulo - São Paulo (SP). Those days when the CALIOP system and ground-based instruments spatially coincided, were selected and analyzed under cloud-free conditions, as well as days when the trajectories of air masses indicated the transport of air parcels from the CALIOP track towards the ground-based sensors. The Lidar Ratio values from the Aeronet/Caliop proposed model was determined and showed good consistency with those initially assumed by the CALIOP Algorithm. Based on the quantitative comparison, a mean difference of 2,17 ± 30,12%. This value shows to be in good agreement with other papers in the CALIPSO validation literature, demonstrating the accuracy of the proposed model. The apparent underestimation in the CALIOP Lidar Ratio values indicates a possible problem with the calibration process, since the Brazilian territory is in the so-called South Atlantic Anomaly (SSA) Region. The Lidar Ratio retrieved by the MSP-Lidar system at IPEN provided a mean difference of 2,34 ± 17,53%, confirming that the accuracy in the Lidar Ratio assumed a priori by the CALIOP algorithms is within the uncertainty range of 30%.

A cidade de Cubatão está localizada na região da baixada santista, no estado de São Paulo. Ela conta com um dos maiores complexos industriais do Brasil, tendo este iniciado as suas atividades na década de cinquenta. Cubatão, tornou-se uma grande potência econômica seguindo as tendências de seu desenvolvimento industrial. Contudo o progresso fabril aliado a ausência de políticas públicas e regulatórias, no que se refere à emissão de poluentes atmosféricos, trouxe graves consequências ambientais. A ausência de leis ocasionou um grande problema ambiental em Cubatão na década de oitenta, época na qual a região atingiu níveis altíssimos de poluição atmosférica, ganhou grande repercussão internacional e deu origem ao termo Vale da morte. Após este acontecimento, foram desenvolvidas as leis regulamentadoras de emissões atmosféricas, tanto no âmbito estadual quanto no federal. Hoje apesar de Cubatão possuir níveis mais baixos de poluição e emissões industriais controladas, é possível notar ultrapassagens dos padrões de qualidade do ar. Baseado no contexto apresentado sobre o município, o presente trabalho tem como objetivo realizar um estudo da dispersão dos poluentes na região de Cubatão-SP utilizando técnicas diversas, como: sensoriamento remoto - técnica Light Detection and Ranging (LIDAR) e dados de satélite - e informações de qualidade do ar disponibilizados pela CETESB. / The city of Cubatão is located in the region of the state of São Paulo. It has one of the largest industrial complexes in Brazil, having started its activities in the fifties. Cubatão, became a major economic power following the trends of its industrial development. However the factory progress, combined with the absence of public and regulatory policies, regarding the emission of atmospheric pollutants, brought serious environmental consequences. The absence of laws caused a major environmental problem in Cubatão in the eighties. The region reached very high levels of air pollution, gaining great international repercussion and giving rise to the term Death Valley. Following this event, regulatory laws about atmospheric emissions were developed, both at the state and federal levels. Today, although Cubatão has lower levels of pollution and controlled industrial emissions, it is possible to observe overcoming air quality standards. Based on the context presented on the municipality, the present work aims to conduct a study of the dispersion of pollutants in the region of Cubatão-SP using several techniques, such as: remote sensing - Light Detection and Ranging (LIDAR) and satellite data - and air quality information provided by CETESB.

A cobertura de nuvens e os aerossóis são os dois principais fatores que modulam a energia solar que atinge a superfície e é absorvida pela atmosfera. Esses dois fatores, portanto, têm um papel essencial no clima do planeta. Há atualmente um interesse nos efeitos radiativos dos aerossóis, particularmente por causa da atividade antrópica, que aumenta sua concentração na atmosfera, e por sua íntima relação com a formação de nuvens. Partículas que podem ser ativadas e ganhar água para se tornarem nevoeiro ou gotas de nuvens, na presença de supersaturação de vapor de água, são chamadas de Núcleo de Condensação de Nuvens. O estudo das partículas que aumentam de tamanho com o ganho de água conforme aumenta a umidade relativa (higroscopicidade) torna-se então de fundamental importância no entendimento da contribuição dos aerossóis na regulação do clima do planeta. O LIDAR é um instrumento promissor no estudo da higroscopicidade dos aerossóis atmosféricos, porque pode operar em ambiente não perturbado e em condições muito próximas da saturação. O LIDAR Raman apresenta a vantagem de poder obter o perfil de vapor de água e retroespalhamento de aerossóis no mesmo volume atmosférico e sem nenhuma suposição a priori a respeito da razão LIDAR Este trabalho objetiva avaliar o crescimento higroscópico do material particulado urbano em São Paulo, Brasil, e em Washington, D.C, Estados Unidos durante a campanha NASA-Discover-AQ com o uso da técnica LIDAR Raman, obtendo o fator de crescimento por higroscopicidade. Apesar da metodologia que se baseia na determinação de uma atmosfera bem misturada com o uso de radiossondagem já ter sido utilizada na literatura, este trabalho acrescenta importantes informações, já que não se tem notícias de outros estudos extensos com múltiplos casos feitos com o LIDAR Raman para avaliação de higroscopicidade nos Estados Unidos, bem como é a primeira vez que este estudo é feito em São Paulo, como resultado de três anos de aquisição de dados. Os resultados mostram que é possível identificar o crescimento higroscópico dos aerossóis em ambas os ambientes de estudo, cuja detecção depende de condições atmosféricas que estão raramente presentes, tornando o estudo da higroscopicidade com o LIDAR um desafio que exige uma extensa coleta de dados. Mostram ainda que a determinação da origem e o estudo conjugado das propriedades químicas da população de aerossóis são informações que auxiliariam no entendimento do comportamento higroscópico, aprofundamentos estes que podem ser derivados deste trabalho. / The cloud cover and aerosols are two main factors that modulate the solar energy that reaches the surface and is absorbed by the atmosphere. These two factors therefore have a key role in global climate. There is currently an interest in the radiative effects of aerosols, particularly because of human activity, increasing its concentration in the atmosphere, and its close relationship with cloud formation Particles that can be activated and gain water to form fog or cloud droplets in the presence of water vapor supersaturation, are called Cloud Condensation Nucleus. The study of particles that increase in size because of the uptake of water under increasing relative humidity conditions (hygroscopicity) then becomes of fundamental importance in understanding the contribution of aerosols in regulating the global climate. The LIDAR is a promising tool in the study of hygroscopic properties of atmospheric aerosols, because it can operate in undisturbed environment and much close to saturation conditions. The Raman LIDAR has the advantage of being able to obtain the profile of water vapor and aerosol backscatter at the same atmospheric volume and no a priori assumption of the LIDAR ratio. This study aims to evaluate the hygroscopic growth of urban particulate matter in Sao Paulo, Brazil, and Washington, DC, United States during the NASA-Discover-AQ campaign using the technique Raman LIDAR, getting the growth factor by hygroscopicity . Although the methodology - which is based on determination of a well-mixed atmosphere using radiosonde - have already been described in the literature, this work adds important information, since they do not have other news with multiple cases extensive studies made with the LIDAR Raman hygroscopicity for evaluation in the United States, and is the first time that this study is done in São Paulo, as a result of three years of data acquisition. The results show that it is possible to identify the hygroscopic growth of aerosol in both environments, whose detection depends on atmospheric conditions that are rarely present, making the study of hygroscopic properties with LIDAR a challenge that requires extensive data collection. Also, show that the determination of origin and the combined study of chemical properties of the population of aerosols would assist in the understanding of hygroscopic behavior.

Os aerossóis e nuvens desenvolvem um papel muito importante nos processos climáticos terrestres por meio das suas contribuições diretas e indiretas no balanço radiativo da atmosfera. A dificuldade na previsão dos processos de mudanças climáticas estão associadas às incertezas na distribuição e propriedades dos aerossóis e nuvens, assim como em suas interações em escala global. Tendo como principal objetivo desenvolver estudos que ajudem na diminuição dessas incertezas, a NASA, em parceria com a agência espacial francesa CNES, desenvolveu a missão do Satélite CALIPSO, que possui a bordo um sistema Lidar denominado CALIOP capaz de estudar o perfil e a distribuição vertical dos aerossóis e nuvens e os processos de interação entre eles. Uma vez que as propriedade ópticas medidas pelo CALIOP são recuperadas utilizando um complexo conjunto de algoritmos, torna-se necessário o desenvolvimento de estudos e metodologias de validação para inferir qual a acurácia das medidas desse sistema. Nesse contexto, foi desenvolvida uma metodologia de avaliação e validação dos valores de Razão Lidar utilizados a priori pelos algoritmos do CALIOP utilizando dois instrumentos de sensoriamento remoto instalados em solo, um sistema Lidar de retroespalhamento elástico instalado no IPEN - São Paulo e o fotômetro solar da rede AERONET instalado em cinco diferentes localidades, Rio Branco - Acre (RB), Alta Floresta - Mato Grosso (AF), Cuiabá - Mato Grosso (CB), Campo Grande - Mato Grosso do Sul (CG) e São Paulo - São Paulo (SP). Foram determinados os dias de medidas correlativas entre os sistemas em solo e o CALIOP e analisados os dados para os dias de medidas com condições livre de nuvens e com trajetórias de massas de ar se deslocando das regiões de medidas do satélite para as regiões de medidas pelos instrumentos fixos. Foram calculados novos valores de Razão Lidar obtidos pelo Modelo Aeronet/Caliop (Modelo A/C) proposto. Esses valores mostraram-se coerentes com aqueles utilizados inicialmente pelo algoritmo do sistema CALIOP. Realizando uma comparação quantitativa, obteve-se uma diferença percentual de 2,17 ± 30,12%, esse valor mostra-se compatível com outros valores obtidos na literatura de validação desse sistema Lidar a bordo do Satélite CALIPSO. Essa subestimação nos valores de Razão Lidar utilizados pelo CALIOP pode estar ocorrendo devido um problema no processo de calibração dos dados do sistema CALIOP, uma vez que o território brasileiro se encontra na região da Anomalia do Atlântico Sul (SAA). A diferença percentual dos valores de Razão Lidar utilizados pelo CALIOP com aqueles obtido por meio de medidas com o sistema Lidar do IPEN forneceram valores de 2,34 ± 17,53%, demonstrando que o modelo de validação proposto é aceitável e acurácia nos valores de Razão Lidar utilizados a priori pelo CALIOP está dentro das margens de incerteza de 30%. / Aerosol and clouds play an important role in the Earths climate process through their direct and indirect contributions to the radiation budget. The largest difficulty in predicting the climate change processes is associated with uncertainties in the distribution and properties of aerosols and clouds, as well as their interactions on a global scale. The CALIPSO mission was developed as part of the NASA program, in collaboration with the French space agency CNES, with the main goal to develop studies that will help to quantify the uncertainties about aerosols and clouds. The CALIPSO satellite carried a Lidar system on board, named CALIOP, as a primary instrument, able to provide the aerosol and cloud vertical profiles and distribution, as well as their interactions. Once the optical properties measured by CALIOP are retrieved, using a complex set of algorithms, it is necessary to study and develop methodologies in order to assess the accuracy of the CALIOP products. In this context, a validation methodology was developed in order to verify the assumed values of the Lidar Ratio selected by the CALIOP algorithms, using two ground-based remote sensing instruments, an elastic backscatter Lidar system (MSP) installed at IPEN in São Paulo and the AERONET sunphotometers operating at five different locations in Brazil, Rio Branco - Acre (RB), Alta Floresta - Mato Grosso (AF), Cuiabá - Mato Grosso (CB), Campo Grande - Mato Grosso do Sul (CG) e São Paulo - São Paulo (SP). Those days when the CALIOP system and ground-based instruments spatially coincided, were selected and analyzed under cloud-free conditions, as well as days when the trajectories of air masses indicated the transport of air parcels from the CALIOP track towards the ground-based sensors. The Lidar Ratio values from the Aeronet/Caliop proposed model was determined and showed good consistency with those initially assumed by the CALIOP Algorithm. Based on the quantitative comparison, a mean difference of 2,17 ± 30,12%. This value shows to be in good agreement with other papers in the CALIPSO validation literature, demonstrating the accuracy of the proposed model. The apparent underestimation in the CALIOP Lidar Ratio values indicates a possible problem with the calibration process, since the Brazilian territory is in the so-called South Atlantic Anomaly (SSA) Region. The Lidar Ratio retrieved by the MSP-Lidar system at IPEN provided a mean difference of 2,34 ± 17,53%, confirming that the accuracy in the Lidar Ratio assumed a priori by the CALIOP algorithms is within the uncertainty range of 30%.