Spectral Enhancement of Imagery for Small Inland Water Bodies Monitoring: Utilization of UAV-Based Data

Jitka Komarkova,Jakub Jech,Pavel Sedlak,Ivana Cermakova

doi:10.29333/jisem/6346

Abstract

The article describes a way for identification of land cover types and consequently land cover changes around a small water body, which is based on spectral enhancement of RGB UAV-based data. A middle-class unmanned aerial vehicle (UAV) – DJI Phantom 3 Pro, was used for data collection. UAV represents a cheap and on-demand available solution for remote data sensing. Its utilization is limited by weather conditions and particular legal regulations must be followed. The article is focused on a monitoring of a small water body and its surrounding by spectral enhancement. Spectral indices, which are calculated only from the visible bands, are used to identify particular land cover types: Color Index of Vegetation Extraction (CIVE), Excess Green (ExG), Excess Red (ExR), Green Leaf Index (GLI), Normalized Green-Red Difference Index (NGRDI), Red-Green-Blue Vegetation Index (RGBVI), Visible Atmospherically Resistant Index (VARI), and ExG – ExR difference. Low pass filtering was used for post-processing and results were simply visualised in a form of classified raster (by natural breaks – Jenks). Even this simple spectral enhancement of imagery supports its visual interpretation. Visible spectral indices highlight particular land cover types, namely green vegetation and water surface but other types of land cover can be distinguished as well.

Highlights

Monitoring land cover changes and water bodies represents an important contemporary issue of our society
The costs are usually lower, measurement does not require a direct access to the monitored area, accuracy and spatial resolution is adequate for monitoring, and data measured in various parts of the electromagnetic spectrum are available
The aim of the paper is to propose a suitable way of monitoring small water bodies and land cover changes in the surroundings, which is based on data collected by a middle-class unmanned aerial vehicle (UAV) and visible spectral indices

Summary

Introduction

Monitoring land cover changes and water bodies represents an important contemporary issue of our society. It means that society is interested in new findings, which can help to understand how the Earth and its components (biophysical spheres, e.g. hydrosphere and biosphere) behave. Studies focusing on land cover/land use change are often realized at national or international level. The local level of the monitoring of land cover/land use change and water bodies is important too but it is not so frequently covered by the studies because it may require a higher spatial resolution that satellite imagery provides. Sensed images are very often used for observation and monitoring changes of landscape and terrain. Multispectral and hyperspectral imagery is important for land cover monitoring because of possibility of calculation

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Conclusion