Multispectral data for environmental studies

Multispectral data for environmental investigations

SAL Engineering, in collaboration with ARPA Campania, carried out some experimental multispectral investigations to research the possibilities of development of the multispectral survey technology applied to environmental monitoring.

The University of Modena and Reggio Emilia has also conducted studies, research and insights on the data obtained, also through the thesis of Dr. Lisa Mosconi. The purpose of this thesis is to investigate the potential and problems related to the use of multispectral images acquired by sensors mounted on board of remotely piloted aircraft (APR), also called more commonly drones, for applications of environmental sciences and environmental protection.

These sensors are sensitive to radiation emitted or reflected on different wavelength intervals of the electromagnetic spectrum, from the visible region (VIS) to that of the near infrared (NIR) and it is precisely this ability to observe beyond the visible, side by side of the ‘high geometric resolution that can be obtained, which makes them particularly interesting for environmental investigations. The acquired data allow to obtain information regarding the stress or vigor of the vegetation, aspects that can also be correlated to other information depending on the territory considered.

The term “environmental investigations” therefore refers to a series of applications that include precision agriculture and the monitoring of portions of the territory affected by problems of soil and groundwater pollution.

In a waste disposal plant, the multispectral survey provides geometric and radiometric information useful to identify and diagnose any malfunctions in the management of wastewater and sewage produced by the decomposition of waste, to characterize the various infrastructures of the plant, to diagnose any phenological consequences and pathological effects on vegetation affected by contamination processes. In addition, it is possible to evaluate the presence or absence of a pollution by leachate inside the pipes and the surrounding soil.

All this was possible thanks to the innovative MAIA multispectral camera developed by SAL Engineering together with Eoptis mounted on board a multirotor drone, which allowed the acquisition of multispectral images, with a degree of detail and accuracy never achieved before.

MAIA + ILS for environmental monitoring and precision agriculture

ILS: the Incident Light Sensor designed for environmental monitoring and precision agriculture

ILS – Incident Light Sensor provides irradiance data at the exact time of shooting for each image and in each spectral band, substantially improving the accuracy of radiometric correction and allowing to conduct multi-temporal multispectral surveys.

Thanks to a renewed cutting-edge software technology for measuring incident light during the survey and thanks to the possibility to manage information related to the position of the sun, ILS now provides more accurate and reliable data.

The multispectral data acquisition system composed by MAIA and ILS writes the exposure and reflectance data of the momentary incident light referring to each single shot of the camera, together with positioning data, environmental data and aircraft asset.

The internal GNSS positioning system provides the precise position of the MAIA multispectral images, but most of all the solution with double GNSS receiver, where one ILS serves as a master base and the other acts as a rover onboard RPAS, gives the possibility to process GNSS data in RTK mode (Real-Time Kinematic), ensuring accuracy close to the centimeter for shots positions.

This aspect triples the speed of photogrammetric processing in the main software based on structure from motion algorythms, and allows to obtain accurate data in a very short time. The RTK solution allows to have an accurate positioning of the center of image, which is fundamental when it is necessary to acquire a sample of images in certain points to investigate a physical phenomenon.

Again, this is of fundamental interest in the field of precision agriculture and environmental protection, where it is important to have a mapping of the conditions ex ante and ex post a natural event, a human action, an unexpected episode, a seasonal evolution.

Agronomic companies, universities and research institutes dealing with agronomic research have for years included data from multispectral survey within the method of data processing and modeling of forecast scenarios.

Come and discover on the dedicated page or on Geo-Matching all the technical features of ILS, the Incident Light Sensor designed for science-based multispectral surveys.

“Geometric calibration and radiometric correction of the MAIA Multispectral Camera” on ISPRS Archives

Geometric calibration and radiometric correction of the MAIA Multispectral Camera

As a result of the Conference “Frontiers in Spectral imaging and 3D Technologies for Geospatial Solutions” that took place in Jyväskylä, Finland, on 25-27 October 2017, a paper has been discussed, published and scientifically reviewed. The title of the article is “Geometric calibration and radiometric correction of the MAIA Multispectral Camera” and it is published on “The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-3/W3, 2017”. This article has been peer-reviewed.

Multispectral imaging is a widely used remote sensing technique, whose applications range from agriculture to environmental monitoring, from food quality check to cultural heritage diagnostic. A variety of multispectral imaging sensors are available on the market, many of them designed to be mounted on different platform, especially small drones. This work focuses on the geometric and radiometric characterization of a brand-new, lightweight, low-cost multispectral camera called MAIA. The MAIA camera is equipped with nine sensors, allowing for the acquisition of images in the visible and near infrared parts of the electromagnetic spectrum.

You can read and download the paper by clicking on the link below.

GEOMETRIC CALIBRATION AND RADIOMETRIC CORRECTION OF THE MAIA MULTISPECTRAL CAMERA