núm. 52 (2017)

Space geodesy has become, in recent years, a fundamental tool for the study of phenomena associated to earth’s dynamics, which allows to establish its essential role in the understanding and mitigation of natural hazards. It implies the establishment of geodetic networks aimed to carry out tectonic and volcano geodesy, with the purpose of knowing the deformation of the earth's crust and its implications for the possibilities of earthquakes and volcanic eruptions occurrence, as well as the use of interferometry techniques (InSAR) to support these analyzes. In Colombia, the Colombian Geological Service gradually has been working in such applications, from the concept of GNSS Space Geodetic instrumentation as imaging geodesy. The GeoRED Project has been gradually implementing a GNSS geodetic network for the study of the geodynamics in the Colombian territory; at the same time, the Research and Monitoring of Volcanic Activity in Colombia has installed some GNSS geodetic stations in several volcanic edifices in the country. In addition, with the support of foreign research institutions, some activities have been carried out on the application of interferometry radar, covering even the study of the land subsidence of the Sabana de Bogotá. Preliminary results obtained until now are showed, using the techniques mentioned above. It is being also illustrated the general aspects of the use of GNSS satellite signals with other research purposes, in order to support the advances in the knowledge of the Colombian territory.

In the following article the methodology comes to detect clouds using Landsat satellite images, which complicates the use of data in the optical domain of the satellites, as influencing their analysis, causing inaccurate atmospheric correction, skewing values index normalized difference vegetation (NDVI), misclassification and land cover changes confusion vegetable coverages. The resulting model becomes a support tool for further studies in multiple disciplines to facilitate the process of analyzing different phenomena or studies being developed. For this is taken as an example, the area between the Central and Occidental mountain ranges near the town of Puerto Berrío, Antioquia, where there is information relating to 12 Landsat 7 satellite images. Cloud detection network analysis is used as a powerful tool to classify different elements, making more efficient computational process, integrating information from multiple sources to incorporate new features and also dispense with the use of statistical models unlike other approaches. The process allowed train the network with EMC 0.0339 with 7 neurons in the hidden layer, with less than 100 iterations for each of the images used. The method obtained an overall accuracy of 91% better than the results achieved with the method of thresholds developed in previous studies, the accuracy was 87.37%.

The average demand of cotton in Colombia from 2006 has fallen from 80 000 tons / year to 30 000, this appears for the strong climate changes, where there meets reflected the bad quality of the fiber of spinning. In this work has identified the effects of the water stress of the cotton crop in the Municipality Villavieja, Huila. With the implementation of 12 images satellites, it was possible to observe the effects of the water stress, the series Landsat 4 TM, 5 TM and 7 ETM+ were implemented with epochs understood by the climatic periods of Colombia (dry and humid). The images were processed in the software Erdas Imagine 9.2, different transformations were applied to them: radiance, reflectance, Normalized Difference Vegetation Index and Normalized Difference Water Index, to finally calculate the Normalized Differential Drought Index. Also applied the Crop Water Stress Index (CWSI) with information of superficial temperature. The validation gave like proved a correlation of R2  = 0.9271 and 0.4757 for dry and humid season, respectively. The Index CWSI has demonstrated to be useful in the programming irrigation. When the threshold value is determinate in the different phenological stages of the crops, it is used to avoid hurts for water stress and decrease in the production of the crops.

Concerns about regional planning summon to engineering to play a more social and human role, guiding the practice of engineering towards intervention, imagination, design and construction of possible scenarios for the realization of ethical territories which promote sustainable, for which artificial intelligence, human development, computation al modeling, geographic Information systems and other mathematical apparatus should attend in support of emerging approaches based on complexity, evolutionary theories or social systems engineering. It is proposed here consider social systems consist of free agents who make their own decisions as socio-technical systems, such as social artifacts, constituent and constituted by concepts like the general welfare, sustainable development, environmental protection, democracy and declining risks, problems on which it is feasible engineering method defined by Billy Vaughn Koen and the use of heuristics to generate the best changes in situations with few resources and poorly understood, addressed to the imaginary design of such systems, encouragement to study their structures, relationships and emergency service of the transformation of possible scenarios achievable scenarios. This document includes two parts: First, a quick look of the theoretical approaches that allow the conceptualization of engineering and modeling socio-technical systems as well as some engineering tools available for the design and operation of the models for the design of territories and the second part is a summary of a case study on implementation as an example for possible cases of empirical study.

There are global trends to access, to use and to secure land ownership, defined by pressures on natural resources, such as mining and oil exploitation; on land for rapid urban urbanization; on re-settlement and reallocation as a result of natural disasters; and on land for food and biofuel productions.  In addition to it, lands markets are globalized and there is a tendency to acquire lands at large scale, and to have large private investments, creating impact on rural and local communities. In the Colombian case, the historical conflicts related to land ownership, to land access, to land use and to subsoil resources exploitation, affected institutions and communities particularly at local level, generating land seizing and forced abandonment of land. Within such context, what is the role of government? How to act timely and efficiently to respond to the described forces and trends, while achieving an efficient land management for both, private and public lands? To face such global pressures, updated and relevant parcel based information is compulsory to get to know beyond the legal status, the ground situation and context on land tenure. Information is essential for both citizens and governments to make assertive decisions, in this sense, efforts should concentrate towards the building, upgrading and maintenance of official and interoperable land records and platforms, overcoming isolated information systems and allowing information exchange, analysis and retrieving, regardless the data sources, the formats and the producer organization.

The state of vegetation growth plays an important role in the ability of all biological aspects of a region to remain diverse and productive in their environment. There were used 3 types of satellite imagery to assess the state of vegetation growth in the Soberanía National Park in Panama. A TerraSAR-X image in polarization HV and an incidence angle of 29° was filtered by 15 different filters in order to reduce speckle and then each of the results was evaluated using assessors Noise Mean Value (NMV), Noise Variance (NV), Mean Square Difference (MSD) and Equivalent Number of Looks (ENL); and according to the criteria established for these evaluators was elected the best result of the filters used to subsequently obtain the backscattering coefficient ( ) of the image. A Landsat 8 image was used equally for the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI), which measure the state of the vegetation, to be correlated with the backscattering coefficient and get an exponential regression depending on such variables. There were obtained therefore two exponential functions where the results were  and  from the backscattering coefficient and were the representative variables of the state of vegetation growth throughout the study area. The correlation between these variables was low (R² = 0.447 and R² = 0.424 for NDVI and EVI respectively), making validation of results with the NDVI and EVI products from MODIS similarly low.

In this paper  presents the spectral characterization of six plant species of interest to the urban trees of Bogotá by a low-cost unmanned aerial system (UAS). For this purpose a hexacopter FH-H800 equipped with PixHawk driver and autonomous flight capacity was assembled. Two standard cameras Canon A2300, one manually modified to allow data capture in the near infrared range was used. The photogrammetric flight planning was made for an altitude of 120 m above the ground in order to cover the area of the Botanical Garden by two flights of ten minutes each one. There were obtained approx. three hundred images with pixel size of 0.10 m covering the three channels of the visible spectrum (B, G, R) channel and the near infrared (NIR). The images were corrected by a photogrammetric process based on structure from motion (SFM) and stereo correspondence (MVS) using open source software that yielded a digital surface model (DSM) and develop multispectral orthofothomosaics (4 bands) with accurately horizontal position of 1.20 m for 90 % of the data. From the orthomosaics, identification and characterization of the spectral response of the following plant species was conducted: magnolia (Magnolia grandiflora), carbonero (Calliandra trinervia), sietecueros (Tibouchina lepidota), roble (Quercus humboldtii), pino colombiano (Podocarpus oleifolius) y sangregao (Croton funckianus). The results indicated that the near-infrared band is essential for the differentiation of these plant species. This work demonstrates the potential of UAS for fast and economical characterization and monitoring of natural or cultivated vegetation.

Quisiera agradecer al Instituto Geográfico Agustín Codazzi y al comité organizador por la invitación, y por haber escogido un título muy estimulante. Podemos pensar que no existe relación entre las técnicas de percepción remota y la paz, y que una conferencia sobre las evoluciones de la percepción remota en los últimos veinticinco años solo va a presentar algoritmos recientes de procesamiento de imágenes. Sin embargo, acepté este título porque existen relaciones entre la percepción remota y la paz. Primero, porque las innovaciones tecnológicas se hacen al ritmo de los ciclos de guerra y paz. Segundo, porque las herramientas geográficas en general y la percepción remota en particular, después de haber sido dedicadas a la descripción del mundo físico, han empezado a interesarse por la sociedad hasta con métodos cuantitativos para finalidades tan importantes como la salud y la paz.

Esta Semana Geomática tiene una característica muy especial frente a los eventos que hemos celebrado en años anteriores: primero, se cumplen 80 años de la fundación del Instituto Geográfico Agustín Codazzi; segundo, el país se dirige hacia un pacto de paz, donde uno de los principales acuerdos gira alrededor de la cuestión rural; tercero, culmina el primer año del segundo mandato del presidente Santos; cuarto, se inicia  la ejecución de un nuevo Plan Nacional de Desarrollo, donde hay unos artículos y unos objetivos que tocan de manera clara y contundente la labor que el Instituto desempeña, y quinto, se presenta un interés muy importante por la gestión del territorio, sobre todo en lo rural y lo regional.

Gastric cancer heads the list of deaths caused by diseases in Colombia, and therefore, its prevention, early detection, and treatment, has become a State policy. This research describes the behavior of gastric cancer in Colombia at the municipal level for the period 2005-2012, using classic spatial regression models, that allowed to identify potential risk factors associated with the phenomenon, and maps of the disease. Through this analysis was possible to determine spatial patterns and clusters, and to classify the territory by zones according to level of risk of prevalence of the disease.

The Web of Linked Data is a new paradigm that enables to explode the Web as a global information space. The principles of Linked Data associated with DANE’s geo-statistical information will enable to overcome current barriers in the information delivering process, and will reach a semantic integration and interoperability of data. In this paper we present the characteristics of a study case for the generation and publication of geo-statistical data according to Linked Data. This prototype is the starting point for integrating Open Government Data, heterogeneous datasets of the Linked Data Web and the innovation processes of the modern DANE.