A discussion on different techniques for GIS data collecting, precision, accuracy and quality of database

Nowadays, is a common sense the importance of geotechnologies in urban planning, transportation engineering and other different areas of knowledge. The Geographic Information System (GIS) is one of the geotechnologies that has been used increasingly. The collection of information and creation of a database are the most expensive, complex and important task in a GIS project. The collection of information results from the direct and indirect measurement of the real world. The reason for creating databases is to register and the maintain the different sources of collecting information. This paper has the objective to present the different techniques for data collection as input in GIS, as well as a brief discussion on the cost associated with the collection of data. Furthermore, comments on precision, accuracy and the quality of database are given.

A discussion on different techniques for GIS data collecting, precision, accuracy and quality of database

Nowadays, is a common sense the importance of geotechnologies in urban planning, transportation engineering and other different areas of knowledge. The Geographic Information System (GIS) is one of the geotechnologies that has been used increasingly. The collection of information and creation of a database are the most expensive, complex and important task in a GIS project. The collection of information results from the direct and indirect measurement of the real world. The reason for creating databases is to register and the maintain the different sources of collecting information. This paper has the objective to present the different techniques for data collection as input in GIS, as well as a brief discussion on the cost associated with the collection of data. Furthermore, comments on precision, accuracy and the quality of database are given

Tecnologias da geoinformação em estudos da dinâmica urbana

This paper explores the application of geoinformation techniques in urban dynamics models. The goal is to discuss the state of the art in order to achieve the advantages for integrating Cellular Automata (CA) models and Multi-Agent Systems (MAS) in Urban/Regional and Transportation Planning. Finally, this work concludes that the urban dynamics models needs to aggregate the geographic reference and the temporal scale in its conceptual and operational structure. Therefore, the geoinformation techniques become an essential instrument for reaching this precondition because they assemble spatial and temporal analysis through Geographic Information Systems (GIS) with CA and MAS models

PROPOSAL OF A TABLE TO CLASSIFY THE RELIABILITY OF BASELINES OBTAINED BY GNSS TECHNOLOGY

The correct data processing of GNSS measurements, as well as a correct interpretation of the results are fundamental factors for analysis of quality of land surveying works. In that sense, it is important to keep in mind that, although, the statistical data provided by the majority of commercials software used for GNSS data processing, describes the credibility of the work, they do not have consistent information about the reliability of the processed coordinates. Based on that assumption, this paper proposes a classification table to classify the reliability of baselines obtained through GNSS data processing. As data input, the GNSS measurements were performed during the years 2006 and 2008, considering different seasons of the year, geometric configurations of RBMC stations and baseline lengths. As demonstrated in this paper, parameters as baseline length, ambiguity solution, PDOP value and the precision of horizontal and vertical values of coordinates can be used as reliability parameters. The proposed classification guarantees the requirements of the Brazilian Law N 10.267/2001 of the National Institute of Colonization and Agrarian Reform (INCRA)

Modelo ionosférico regional aplicado ao Sistema de Posicionamento Global – GPS

The positioning of points with the GPS system has become an important tool used in many different areas of knowledge. However, in some situations, the demand for great accuracies has caused the inconvenience of high cost when dual frequency receptors are purchased. Even with technological advances, the ionosphere is one of the error sources that affect the positioning of points. For users that have dual frequency equipments, this error is modeled with great efficiency through the processing of data with iono free solution. In Brazil, most users have equipments that gather information from the C/A code only, and/or from the C/A code and carrier L1. In this case, a few models are used, like the Klobuchar’s for example, with error reduction for absolute positioning of 50%, approximately. For relative positioning, with bases further than 20 km, the use of this model is not the most appropriate. In this context, this work consists in the development of a method that can model the ionospherical delay with a second degree polynomial, based on sequential adjustment of observations. The necessary information for this modeling was taken from GPS stations of the Brazilian Network for Continuous Monitoring - RBMC. Evenly, with Single Point Positioning, it has been proved that the offered model has lead to a positional error reduction of near 65% if compared to the processing without the use of any ionospherical model. Key words: Regional model, ionosphere, sequential adjustment, GPS.O posicionamento de pontos com o sistema GPS é uma ferramenta importante e aplicável nas mais diferentes áreas do conhecimento. No entanto, em algumas situações, a exigência de informações mais precisas e exatas levou à aquisição de receptores de dupla freqüência, que elevam os custos. Mesmo com os avanços tecnológicos, a ionosfera é uma das fontes de erro que mais afetam o posicionamento de pontos. Para os usuários que possuem equipamentos de dupla freqüência, este erro é modelado com grande eficiência por meio do processamento de dados com solução iono free. No Brasil, a maioria dos usuários possui equipamentos que captam informações apenas do código C/A e/ou código C/A e portadora L1. Neste caso, se faz uso de alguns modelos, como por exemplo, o de Klobuchar, com redução do erro nos posicionamentos absolutos de, aproximadamente, 50%. Contudo, nos posicionamentos relativos, com bases superiores a 20 km, a utilização deste modelo não é a mais indicada. Neste contexto, este trabalho apresenta o desenvolvimento de um método que possibilita modelar o atraso ionosférico por meio de um polinômio do segundo grau, baseado no ajustamento seqüencial das observações. As informações necessárias para esta modelagem são as fornecidas pelas estações GPS da Rede Brasileira de Monitoramento Contínuo - RBMC. Horizontalmente, por meio do método de posicionamento Single Point comprovou-se que o modelo proposto proporcionou uma redução no erro posicional de aproximadamente 65%, quando comparado com o processamento sem a utilização de nenhum modelo ionosférico. Palavras-chave: Modelo regional, ionosfera, ajustamento seqüencial, GPS

Investigating the relationship between road geometry and severe bus accidents in Brazil

The objective of this paper is to investigate the relationship between road geometry and severe bus accidents in Brazil, based on an adaptation of the Umbrella Handle Model (UHM) and emphasizing the influence of unbalanced centripetal acceleration in the occurrence of these events. Three accidents of this type were selected for study, all of them recorded along or close to horizontal curves of Brazilian highways (Trindade Access, RJ 155 and SP 125 roads). The variation in centripetal acceleration of vehicles traveling under operating speed along each “smoothed tangent” was measured using the Keuwlsoft Accelerometer Counter app for smartphone. Transverse and longitudinal acceleration peaks were highlighted for each study section, and, in the first case, the critical variations refer precisely to the locations of the RJ 155 and SP 125 roads where bus accidents were recorded. With regard to the Road Risk Index (RRI), with the exception of the RJ 155 road, the highest RRI values among all combinations between a tangent and a sequential horizontal curve were also observed for the places of occurrence of the investigated accidents

Modelo ionosférico regional aplicado ao Sistema de Posicionamento Global – GPS

The positioning of points with the GPS system has become an important tool used in many different areas of knowledge. However, in some situations, the demand for great accuracies has caused the inconvenience of high cost when dual frequency receptors are purchased. Even with technological advances, the ionosphere is one of the error sources that affect the positioning of points. For users that have dual frequency equipments, this error is modeled with great efficiency through the processing of data with iono free solution. In Brazil, most users have equipments that gather information from the C/A code only, and/or from the C/A code and carrier L1. In this case, a few models are used, like the Klobuchar’s for example, with error reduction for absolute positioning of 50%, approximately. For relative positioning, with bases further than 20 km, the use of this model is not the most appropriate. In this context, this work consists in the development of a method that can model the ionospherical delay with a second degree polynomial, based on sequential adjustment of observations. The necessary information for this modeling was taken from GPS stations of the Brazilian Network for Continuous Monitoring - RBMC. Evenly, with Single Point Positioning, it has been proved that the offered model has lead to a positional error reduction of near 65% if compared to the processing without the use of any ionospherical model. Key words: Regional model, ionosphere, sequential adjustment, GPS.O posicionamento de pontos com o sistema GPS é uma ferramenta importante e aplicável nas mais diferentes áreas do conhecimento. No entanto, em algumas situações, a exigência de informações mais precisas e exatas levou à aquisição de receptores de dupla freqüência, que elevam os custos. Mesmo com os avanços tecnológicos, a ionosfera é uma das fontes de erro que mais afetam o posicionamento de pontos. Para os usuários que possuem equipamentos de dupla freqüência, este erro é modelado com grande eficiência por meio do processamento de dados com solução iono free. No Brasil, a maioria dos usuários possui equipamentos que captam informações apenas do código C/A e/ou código C/A e portadora L1. Neste caso, se faz uso de alguns modelos, como por exemplo, o de Klobuchar, com redução do erro nos posicionamentos absolutos de, aproximadamente, 50%. Contudo, nos posicionamentos relativos, com bases superiores a 20 km, a utilização deste modelo não é a mais indicada. Neste contexto, este trabalho apresenta o desenvolvimento de um método que possibilita modelar o atraso ionosférico por meio de um polinômio do segundo grau, baseado no ajustamento seqüencial das observações. As informações necessárias para esta modelagem são as fornecidas pelas estações GPS da Rede Brasileira de Monitoramento Contínuo - RBMC. Horizontalmente, por meio do método de posicionamento Single Point comprovou-se que o modelo proposto proporcionou uma redução no erro posicional de aproximadamente 65%, quando comparado com o processamento sem a utilização de nenhum modelo ionosférico. Palavras-chave: Modelo regional, ionosfera, ajustamento seqüencial, GPS

EVALUATION OF THE NETWORK OF HYDRANTS IN THE CITY OF SÃO CARLOS-SP RELATIONSHIP TO URBAN EXPANSION, POPULATION DENSITY AND FIRE FIGHTING

The number of fire occurrences has increased year by year in various Brazilian cities and most of these claims is destructive and cause deaths. One of the main factors responsible for the negative results related to fires is the insufficient quantity of hydrants installed in the cities, since the expansion of the urban network and the settlements of the population occurs faster than the installation of these equipments. This study evaluates the distribution of hydrants network in the city of São Carlos-SP regarding allocated fire agents and the population density. It also have been analyzed the relationship among the expansion of the urban area, population growth and the presence of hydrants, in order to estimate the growth of the potential risk areas of fires. The results shows that the city of São Carlos-SP features hydrants deficiency, the installed network covers only one third of the urban area and that only part of the urban population is served by of the equipments coverage radius

PROPOSAL OF A TABLE TO CLASSIFY THE RELIABILITY OF BASELINES OBTAINED BY GNSS TECHNOLOGY

The correct data processing of GNSS measurements, as well as a correct interpretation of the results are fundamental factors for analysis of quality of land surveying works. In that sense, it is important to keep in mind that, although, the statistical data provided by the majority of commercials software used for GNSS data processing, describes the credibility of the work, they do not have consistent information about the reliability of the processed coordinates. Based on that assumption, this paper proposes a classification table to classify the reliability of baselines obtained through GNSS data processing. As data input, the GNSS measurements were performed during the years 2006 and 2008, considering different seasons of the year, geometric configurations of RBMC stations and baseline lengths. As demonstrated in this paper, parameters as baseline length, ambiguity solution, PDOP value and the precision of horizontal and vertical values of coordinates can be used as reliability parameters. The proposed classification guarantees the requirements of the Brazilian Law N( 10.267/2001 of the National Institute of Colonization and Agrarian Reform (INCRA