The main objective of this research is to analyze deforestation in State Sinaloa during the period 1990-2014. For this, "deforestationhot-spot areas" were identified, by crossing maps of 1993 and 2011 at a 1:250,000 scale with knowledge from environmental and forest experts from each region. Landsat images from 1990 and 2014 and Terra Amazon System were used to monitor the most critical hot spot area, applying Linear Spectral Mixture Analysis and Image Segmentation Ground Product. In order to generate the map deforestation year zero (1990), every segmented object of ground product was visually assigned to "Forest" and "No-Forest" categories. Therefore, gains and losses were interpreted for the map deforestation year one (2014). Those products were validated with the help of experts on the subject and applying a confusion matrix. Results obtained indicated that the highest forest loss was located in North-Central Sinaloa (hot spot area number two) by establishing the average annual rate of deforestation of 4741.90 ha/year with an average rate of 0.60%, being higher than the national average rate (0.37%). This result affects directlyon calculation of carbonfluxes at nationallevel.

The new generation, low-cost U-blox ZED-F9P receiver was evaluated and statistically compared by GNSS observations on a geodesic monument, through both Precise Point Positioning and Static relative positioning techniques with a distance of 33 km from the references station. This was done with the purpose of checking the use feasibility of the low-cost receiver of similar gamma in topographic-geodesic works. To that end, four scenarios were considered: in the first scenario, the static relative positioning with the low-cost equipment was applied; in the second scenario, the static relative positioning with a geodetic receiver was applied. Both scenarios were processed with commercial software. The third and fourth scenarios were processed with Precise Point Positioning techniques through the RTKLIB software. The results show that Precise Point Positioning techniques get a precision of 1 cm through the use of low-cost equipment which is suitable to apply in geodetic works. In the static relative method, the precision obtained is 7 mm, indicating the possibility of using the low-cost equipment in both survey and geodetic high precision works, considering a line base ≤30 Km, according to the Instituto Nacional de Estadística y Geografía normative.

A positional accuracy obtained by the Precise Point Positioning and static relative methods was compared and analyzed. Test data was collected using low-cost GNSS receivers of single- and dual-frequency in urban areas. The data was analyzed for quality using the TEQC program to determine the degree of affectation of the signal in the urban area. Low-cost GNSS receivers were found to be sensitive to the multipath effect, which impacts positioning. The horizontal and vertical accuracy was evaluated with respect to Mexican regulations for the GNSS establishment criteria. Probable Error Circle (CEP) and Vertical Positioning Accuracy (EPV) were performed on low cost GNSS receiver observation data. The results show that low-cost dual-frequency GNSS receivers can be used in urban areas. The precision was obtained in the order of 0.013 m in the static relative method. The results obtained are comparable to a geodetic receiver in a geodetic baseline of <20 km. The study does not recommend using single and dual frequencies low cost GNSS receivers based on results obtained by the Precise Point Positioning (PPP) method in urban areas. The inclusion of the GGM10 model reduces the vertical precision obtained by using low cost GNSS receivers in both methods, conforming to the regulations only in the horizontal component.

Se evalúa una línea base geodésica mediante la implementación de antenas y receptores de bajo costo en sistemas embebidos, así como un receptor geodésico de una frecuencia. Estas mediciones fueron ligadas a una estación de referencia continua de la Red Geodésica Nacional Activa, ubicada en Culiacán, Sinaloa, con el objetivo de determinar la precisión de los equipos de bajo costo estudiados. Para ello se analizan las coordenadas y distancias obtenidas al aplicar el método de posicionamiento diferencial con software académico y comercial. Los resultados presentan diferencias de orden milimétrico entre el posicionamiento con un receptor geodésico y uno de bajo costo para una línea base de 5.1 km que hacen posible la utilización de equipos de bajo costo en trabajos geodésicos y topográficos.

This study aimed to measure and validate altitudes from existing sources with direct GNSS measurements and airborne lidar data. For this purpose, 12 mountain peaks located in the south part of Polish territory were selected. Measurements were performed using a GNSS receiver using the Real-Time Kinematic (RTK) or static techniques enabling altitude measurements with accuracy of 10 cm. GNSS was treated as the primary data source, as the direct field measurements can determine the highest point on each peak. The obtained results were confronted with historical, internet sources, and official altitude data. Moreover, each altitude was determined using lidar data from an airborne lidar dataset of Poland from the ISOK program and provided by the national agency. Significant discrepancies in data were already detected during the analysis of internet materials and traditional maps, up to a few meters. The differences between measured and internet sources in altitude of mountain peak range from 27 cm to 504 cm. This study has shown the need to re-measure the altitudes of the mountain peaks and determine the highest point correctly.