Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Geodetic data capture, revision, processing, analysis and integration anywhere in the world are directed to opportunely produce quality inputs and products under reference frames and proved standards in order to be useful in any spatial data infrastructure. To this effect, it is essential to use methodologies with steps that guide the implementation of effective methods and worNing procedures to reach the expected objectives. According to the above the methodological guides used in the National Institute of Statistics and Geography (INEGI) in order to support the National Subsystem of Geographic and Environmental Information are described in this article.

Mining is increasingly important to analyze both its environmental and social impacts. However, the information on the territorial deployment of this activity is not of public domain. In response to this problem, we present the full Mapping metallic mining in Mexico. By using Geographic Information Systems we elaborated an Atlas, in which is shown the spatial deployment of this activity in all the Country. Mainly we present the list of projects and mining concessions which are inside of important areas for water resources or under some category of environmental protection and indigenous territories.

With the popularity of UAVs (Unmanned Aerial Vehicles), the aerial photography methaod for mapping small areas has become an increasingly viable alternative, providing spatial resolution adequate to its end. In this study, the georeferencing of rural properties, based on aerial photographs covering using UAV, it wasdeveloped in an area of approximately 80 ha. Was developed as a proposition of indirect measurement of natural boundaries in areas of difficult access and as an alternative to geodetic survey with GNSS receivers, in order to comply with accuracy requirements set out in INCRA’s Technical Manual of Positioning. In the implementation stage, data collection was made with use of GNSS receivers and photogrammetric survey with a small UAV for planimetric mapping. As a result of the photogrammetric process, an orthophoto and a planimetric map resulting of the vectoring of the ortophoto ware generated. For quality control, a comparison was made with coordinates of the points in the orthophoto and the map with the coordinates of homologous points on the ground, coming to an accuracy of 0.279 m for 90% of the extracted coordinates of the orthophoto and 0.281 m for the resulting coordinates of the map. These values are compatible to INCRA’s Technical Standard, which requires precision of 3.0 m for natural limits and 7.5 m for inaccessible limits. Quality control was based on Cartographic Accuracy Standard for Digital Cartography (PEC-PCD) and, through statistical test, it was found that the product can be classified in Class A in scale 1:1,000. 

Estimating the expected value of a function over geographic areas is problem with a long history. In the beginning of the XXth century the most common method was just the arithmetic mean of the field measurements ignoring data location. In 1911, Thiessen introduced a new weighting procedure measuring influence through an area and thus indirectly considering closeness between them. In another context, Quenouville created in 1949 the jackknife method which is used to estimate the bias and the standard deviation. In 1979, Efron invented the bootstrap method which, among other things, is useful to estimate the expected value and the confidence interval (CI) from a population. Although the Thiessen’s method has been used for more than 100 years, we were unable to find systematic analysis comparing its efficiency against the simple mean, or even to more recent methods like jackknife or boostrap. In this work we compared four methods to estimate de expected value. Mean, Thiessen, the so called here jackknifed Thiessen and bootstrap. All of them are feasible for routine use in a network of fixed locations. The comparison was made using the Friedman’s Test after a Monte Carlo simulation. Two cases were taken for study: one analytic with three arbitrary functions and the other using experimental data from daily rain measured with a satellite. The results show that Thiessen’s method is the best estimator in almost all the cases with a 95% of confidence interval. Unlike the others, the last two considered methods supply a suitable CI, but the one obtained through jacknifed Thiessen was more accurate, opening the door for future work. 

Evaluation and indicators definition is an issue in the context of Spatial Data Infrastructures (SDI). Previous studies have evaluated first and second generations of SDI in comparison to their planned or anticipated development. This is following an ex- ante approach. However, current SDI trends requires consideration of additional elements for a proper evaluation. The rise of mobile devices, sensors and the growing citizen collaboration are driven the SDI development to a third generation which demands interactive contents, frequently updates, real-time and participation. This paper proposes a system of indicators aimed at evaluating the performance of new SDI trends under an ex-post approach, i.e. after its development. The indicator system assesses two dimensions of management processes that occur in the GeoWeb: participation (through dialogue and empowerment) and dynamism. This work contributes to the improvement of existing SDI evaluation systems by integra- ting specific indicators for new technology trends.

Since 1997 SIRGAS (Geocentric Reference System for the Americas) is acting for establishing a unified SIRGAS Vertical Reference System (SVRS) in Latin Ameri- ca and the Caribbean. The standards, procedures and activities aiming the definition and realization of the SVRS are now directed to meet the modern international requirements of integration into a Global Vertical Reference System (GVRS) to support the needs for Earth Observation Systems. These statements imply in a uni- fication of the existing National Vertical Reference Systems (NVRS), each one with its respective Frame (NVRF) and Vertical Datum (NVD) realized in the geopoten- tial space. The study of new possibilities for connecting NVRS in a global basis is in the context of the International Association of Geodesy (IAG) main activities. However, most of modern requirements are not immediately applicable for building the SVRS because the differences in the conception and realization of each NVRS in the SIRGAS region. In this work an overview about the status of NVRS, NVR Fand NVD in South America is presented. The most important characteristics for unifying NVRS in a global context as well as the main related problems are pre- sented. Some emphasis is given on the activities of SIRGAS-Working Group III directed for facing the integration problems in South America. The poor data availability, unknown discrepancies among NVRS, different data collecting and processing strategies for establishing the networks, and other error sources are discussed. The possibilities coming from new strategies and modern tools are dis- cussed mainly by considering new missions and global data basis of Geodesy. 

This paper describes the distinct existing systems to reference the height of objects and its possible applications in the structuring of 3D cadastre. It discusses advantages and inconveniences in the utilization of each one of them for the position- ing of terrestrial objects in space.  Hypotheses based on similar studies of cases in 3D cadastre are analyzed, without the pretension of covering the totality in the same manner. The developed theory is applied to position apartments that are part of private residential buildings (3D parcels) and elements of road work (3D land objects), demonstrating the correlations between the distinct systems of heights.  It is possible to conclude from the results that the ellipsoid of revolution is the most appropriate reference surface for 3D parcels and generally all 3D land object heights. Furthermore, for certain territorial 3D objects, it may be necessary to utilize an equipotential surface to reference their heights. Regarding the precisions required for the positioning and sizing of the plots and 3D objects, it is concluded that both must be carefully analyzed and defined in the cadastral legislation. It is not possible to set a single precision for all, parcels and land objects, since the accuracies depend of the function of the cadastral object.

The importance of the integrated territorial information generated by the multipurpose cadastre for urban planning actions motivated the realization of this research, whose principal objective is to analyze the content and the application of the multipurpose cadastre as an instrument for urban requalification. Through the analysis, carried out with the aid of geotechnologies based on Geographic Information Systems, the aim was to identify and select properties that attend predefined parameters, with the purpose of suggesting their requalification. The area chosen for the proposed analysis was the Boa Vista district and adjacent areas. Localized in the central region of Recife city, Brazil, which have a great variety of properties and services, whose occupation is characterized by areas that are in real state expansion, in contrast with abandoned zones and urban deterioration. As a result. As a result, we present in this article the methodology and results of analyzes for the identification of land for the position for replacement and land whose constructive potential can be transferred to another property.

Throughout this article, it is intended to share a particular experience of positional accuracy evaluation, explaining its bases, design, performance and result’s pro-cessing, with the aim to contribute ideas to the important and complex issue related with quality assurance of the geographic products. It is explained, too, that quality evaluation contributes to put into practice the fitness for use quality notion, which is, nowadays, relevant in the international scene. 

The Volunteered Geographic Information (VGI), understood as geographic information collected by volunteers, experienced or not, in an organized way, for collaborative applications or free licenses projects has become an alternative source of geographic information and its use is growing rapidly. Therefore, it is necessary to establish quality parameters to the VGI, in order to obtain a product confidence by consumers and businesses. The elements of the traditional quality established in the ISO 19113 standard, mark a guideline to follow, but do not meet the new implica- tions that entails VGI.  The paradigm shift introduced by Web 2.0, where the user goes from being a mere spectator of the information to be a content provider, shows the way to search for additional measures. Reliance on the contributions of volunteers turned into mapping producers depends on their acceptance by other users. Furthermore, expe- rience and involvement in the project will mark the reputation of volunteers. There- fore, volunteer’s trust and reputation are related each other becoming in new dimensions of quality specific to the VGI.