Publication: CUANTIFICACIÓN DEL CAMPO DE VELOCIDADES SUPERFICIALES MEDIANTE IMÁGENES TOMADAS CON DRONES EN EL ESTUARIO DEL RÍO MAIPO
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Date
2022-11
Authors
ARAVENA PÉREZ, BRUNO ANTONIO
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Abstract
El uso de drones como instrumento de medición de variables cuantitativas y cualitativas se ha vuelto con el avance de la tecnología una herramienta versátil para generar información fácil y rápida, estos equipos pueden llegar a lugares de difícil acceso para el hombre y ser operados de forma totalmente segura. En comparación con otras tecnologías, se establece una forma sencilla de realizar mediciones con el uso de sensores ubicados sobre el mismo equipo, como lo puede ser, por ejemplo, una cámara. Esta herramienta es utilizada en el presente estudio para medir la velocidad del flujo superficial en el estuario localizado en la desembocadura del Río Maipo (región de Valparaíso, Chile), mediante la captura de imágenes de alta definición es posible establecer en el tiempo el movimiento superficial de la corriente y determinar el campo de velocidades en la superficie. En particular, para este propósito se emplea un programa desarrollado en Matlab que emplea la metodología PIV (particle image velocimetry). En este sentido, se comparan las velocidades obtenidas mediante toma de imágenes con equipo aéreo con las medidas en terreno, con la intención de establecer la factibilidad de usar este tipo de herramientas en la captura de velocidades en el flujo de la zona de estudio y en general en las zonas estuarinas de la costa de Chile. En este trabajo es descrito el procedimiento para la obtención de velocidades y el procesamiento de las imágenes capturadas, también se analiza el coste computacional y criterios para ahorrar tiempo de procesamiento. Adicionalmente, se estudian distintas bandas e índices espectrales a modo de analizar su factibilidad en incrementar el conteo de vectores, comparando los resultados de las bandas roja, verde, azul y el índice de turbidez normalizado NDTI.
En este estudio se logra validar la metodología para obtener los campos de velocidades en el Estuario del Río Maipo con indicadores sobre un 80%, siendo el principal alcance su factibilidad para estudios posteriores en diferentes ambientes estuarino. Por último, se concluye con recomendaciones para la correcta aplicación del método.
The use of drones as an instrument for measuring quantitative and qualitative variables has become, with the advancement of technology, a versatile tool to generate information easily and quickly, this equipment can reach places that are difficult for man to access and totally safe. Compared to other technologies, a simple way of making measurements is established with the use of sensors located on the same equipment, such as, for example, a camera. This tool is used in the present study to measure the speed of surface flow in the estuary located at the mouth of the Maipo River (Valparaíso region, Chile), by capturing high-definition images it is possible to establish the surface movement over time of the current and determine the velocity field at the surface. For this purpose, a program developed in Matlab that uses the PIV (particle image velocimetry) methodology is used. In this sense, the velocities obtained by taking images with aerial equipment are compared with those measured on the ground, with the intention of establishing the feasibility of using this type of tool in capturing velocities in the flow of the study area and in general in the estuarine zones of the coast of Chile. In this work, the procedure for obtaining speeds and the processing of the captured images is described, the computational cost and criteria to save processing time are also analyzed. Additionally, different bands and spectral indices are studied in order to analyze their feasibility in increasing the count of vectors, comparing the results of the red, green, blue bands and the NDTI normalized turbidity index. In this study, it is possible to validate the methodology to obtain the velocity fields in the Maipo River Estuary with indicators over 80%, the main scope being its feasibility for subsequent studies in different estuarine environments. Finally, it concludes with recommendations for the correct application of the method
The use of drones as an instrument for measuring quantitative and qualitative variables has become, with the advancement of technology, a versatile tool to generate information easily and quickly, this equipment can reach places that are difficult for man to access and totally safe. Compared to other technologies, a simple way of making measurements is established with the use of sensors located on the same equipment, such as, for example, a camera. This tool is used in the present study to measure the speed of surface flow in the estuary located at the mouth of the Maipo River (Valparaíso region, Chile), by capturing high-definition images it is possible to establish the surface movement over time of the current and determine the velocity field at the surface. For this purpose, a program developed in Matlab that uses the PIV (particle image velocimetry) methodology is used. In this sense, the velocities obtained by taking images with aerial equipment are compared with those measured on the ground, with the intention of establishing the feasibility of using this type of tool in capturing velocities in the flow of the study area and in general in the estuarine zones of the coast of Chile. In this work, the procedure for obtaining speeds and the processing of the captured images is described, the computational cost and criteria to save processing time are also analyzed. Additionally, different bands and spectral indices are studied in order to analyze their feasibility in increasing the count of vectors, comparing the results of the red, green, blue bands and the NDTI normalized turbidity index. In this study, it is possible to validate the methodology to obtain the velocity fields in the Maipo River Estuary with indicators over 80%, the main scope being its feasibility for subsequent studies in different estuarine environments. Finally, it concludes with recommendations for the correct application of the method
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Keywords
INGENIERÍA CIVIL -- INNOVACIONES TECNOLOGICAS -- DRONES , SISTEMAS DE INFORMACIÓN GEOGRÁFICA , DRON