Análisis Comparativo Del Posicionamiento GNSS Utilizando Receptor De Bajo Costo U-Blox De Doble Frecuencia Para Aplicaciones Topógrafo-Geodésicas

Se evaluó y comparó estadísticamente el posicionamiento obtenido a través del receptor de bajo costo U-blox ZED-F9P de nueva generación con un receptor geodésico, realizando observaciones GNSS sobre un vértice geodésico mediante del método de Posicionamiento Puntual Preciso y relativo estático, con una distancia de 33 km a la estación de referencia. Esto, con la finalidad de probar la factibilidad de utilizar receptores de bajo costo de gama similares en trabajos topográficos-geodésicos. Para ello, se consideran cuatro escenarios; en el primer escenario, se aplicó la técnica relativo estático con el equipo de bajo costo, en el segundo escenario se procesó con un receptor geodésico en modo relativo estático; ambos mediante un software comercial. Para el tercer y cuarto escenario, se procesó modo Posicionamiento Puntual Preciso con el software RTKLIB. Los resultados muestran que para la técnica Posicionamiento Puntal Preciso la precisión lograda de 1 cm por el equipo de bajo costo es apta para realizar trabajos geodésicos. En el método relativo estático, la precisión lograda de 7 mm indica que es posible utilizar el equipo de bajo costo para trabajos topógrafos-geodésicos de alta precisión considerando una línea base ≤33 km, esto, según la normatividad del Instituto Nacional de Estadística y Geografía. 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

Flood-Prone Area Delineation in Urban Subbasins Based on Stream Ordering: Culiacan Urban Basin as a Study Case

Urban development decreases infiltration, increases the runoff velocity, and reduces the concentration times. This situation increases the flood risk in urban watersheds, which represent a management challenge for urban communities and authorities. To increase the resilience of communities due to modifications of the hydrological cycle produced by climate change and urban development, a methodology is proposed to delineate flood-prone areas in urban basins. This methodology is implemented in an urban subbasin of Culiacan, Mexico, and is based on stream order. A high-resolution digital elevation model was used, which was validated independently through a photogrammetric flight with an unmanned aerial vehicle and ground control points obtained with GNSS (global navigation satellite systems) receivers. Morphometric parameters related to geometry, shape, relief, and drainage network aspects of the subbasin were determined and analyzed. Then, flood-prone area zonation was carried out based on stream-order classification and flow direction. Fieldwork was also carried out for the inspection of the sewage network conditions. This methodology simplifies the identification of the flood-prone areas in urban subbasins without carrying out complex hydraulic calculations

Effect of photogrammetric RPAS flight parameters on plani-altimetric accuracy of DTM

Remotely piloted aerial systems (RPASs) are gaining fast and wide application around the world due to its relative low-cost advantage in the acquisition of high-resolution imagery. However, standardized protocols for the construction of cartographic products are needed. The aim of this paper is to optimize the generation of digital terrain models (DTMs) by using different RPAS flight parameters. An orthogonal design L18 was used to measure the effect of photogrammetric flight parameters on the DTM generated. The image data were acquired using a DJI Phantom 4 Pro drone and six flight parameters were evaluated: flight mode, altitude, flight speed, camera tilt, longitudinal overlap and transversal overlap. Fifty-one ground control points were established using a global positioning system. Multivision algorithms were used to obtain ultra-high resolution point clouds, orthophotos and 3D models from the photos acquired. Root mean square error was used to measure the geometric accuracy of DTMs generated. The effect of photogrammetric flight parameters was carried out by using analysis of variance statistical analysis. Altimetric and planimetric accuracies of 0.38 and 0.11 m were achieved, respectively. Based on these results, high-precision cartographic material was generated using low-cost technology