2:30 PM - 2:45 PM
[STT40-04] Measurement Method of Soil-Moisture in the Field by Near-Infrared Multi-Spectrum Camera on UAV
★Invited Papers
Keywords:Near-Infrared Multi-Spectrum Camera, UAV, Soil-Moisture
Introduction
Our research group is considering the application of multispectral/hyperspectral cameras for the purpose of utilizing in disaster site surveys that require rapidity and safety isolation (non-contact).
At present, we are examining the observation using UAV for the purpose of supplementing the observation by ground observation, manned aircraft and artificial satellites. This time, we will report on a demonstration test in which a near infrared multi-spectrum camera was mounted on a UAV and the water content condition of the surface soil was observed from the sky.
Technical features
1)The purpose was specialized in observation and measurement of soil moisture using a solar light source, and in addition, miniaturization of cameras and peripheral systems was aimed at so as to be mountable on a UAV. Though the absorption spectrum property of the water appears in 1450nm band, the measurement of 1450nm band itself is impossible by the effect of the water in the atmosphere, when the sun light source is used, and the measurement band was used near 1300nm and near 1500nm. 2)The mounted multispectral camera adopts the snapshot system without line scan, and it is easy to associate the photographing crush with the three-dimensional position coordinate based on photographing position and photographing angle. 3)For discrimination and discrimination of the soil to be measured from the other atmosphere, clouds, vegetation, etc., the standard data based on the difference in spectral characteristics of each shoot object is used.
Measurement method
UAV was equipped with a near infrared multispectral camera via a gimbal, a control computer and a battery. For the ground surface including the shoot object, the photographing of vertical downward and oblique downward from the sky was carried out. Photographs of the standard reflectors were also taken simultaneously for correction of the reflection intensity. In the spectral analysis, after the dark current correction and the strength correction by the standard reflector data were carried out, the normalization by NDSI was carried out for the error factor relaxation.
Experimental results
As a result of measurement and image analysis, this paper shows the possibility of objectively showing water content and distributed zone by discriminating differences in water content conditions for narrow regions of several 10cm square in imaging data from sky 30m. And, the difference of water content state by the difference of particle size and particle size distribution of the photographing object can also be recognized. It was confirmed that the difference of the water content state could be distinguished on the substrate of sandy soil and gravel soil, even if the particle size and particle size distribution were equivalent.
Tasks and future goals
It is necessary to examine and improve the following. 1) Correction for the incident condition of sunlight as a light source. 2) Correction for the effect of moisture in the atmosphere. 3) Temperature correction when the amount of water contained in the object soil is large. At present, it will remain in the qualitative evaluation, but in the future, imaging is carried out by changing the moisture content of photographing object sample stepwise, and the verification on the quantitative evaluation will be carried out.
Our research group is considering the application of multispectral/hyperspectral cameras for the purpose of utilizing in disaster site surveys that require rapidity and safety isolation (non-contact).
At present, we are examining the observation using UAV for the purpose of supplementing the observation by ground observation, manned aircraft and artificial satellites. This time, we will report on a demonstration test in which a near infrared multi-spectrum camera was mounted on a UAV and the water content condition of the surface soil was observed from the sky.
Technical features
1)The purpose was specialized in observation and measurement of soil moisture using a solar light source, and in addition, miniaturization of cameras and peripheral systems was aimed at so as to be mountable on a UAV. Though the absorption spectrum property of the water appears in 1450nm band, the measurement of 1450nm band itself is impossible by the effect of the water in the atmosphere, when the sun light source is used, and the measurement band was used near 1300nm and near 1500nm. 2)The mounted multispectral camera adopts the snapshot system without line scan, and it is easy to associate the photographing crush with the three-dimensional position coordinate based on photographing position and photographing angle. 3)For discrimination and discrimination of the soil to be measured from the other atmosphere, clouds, vegetation, etc., the standard data based on the difference in spectral characteristics of each shoot object is used.
Measurement method
UAV was equipped with a near infrared multispectral camera via a gimbal, a control computer and a battery. For the ground surface including the shoot object, the photographing of vertical downward and oblique downward from the sky was carried out. Photographs of the standard reflectors were also taken simultaneously for correction of the reflection intensity. In the spectral analysis, after the dark current correction and the strength correction by the standard reflector data were carried out, the normalization by NDSI was carried out for the error factor relaxation.
Experimental results
As a result of measurement and image analysis, this paper shows the possibility of objectively showing water content and distributed zone by discriminating differences in water content conditions for narrow regions of several 10cm square in imaging data from sky 30m. And, the difference of water content state by the difference of particle size and particle size distribution of the photographing object can also be recognized. It was confirmed that the difference of the water content state could be distinguished on the substrate of sandy soil and gravel soil, even if the particle size and particle size distribution were equivalent.
Tasks and future goals
It is necessary to examine and improve the following. 1) Correction for the incident condition of sunlight as a light source. 2) Correction for the effect of moisture in the atmosphere. 3) Temperature correction when the amount of water contained in the object soil is large. At present, it will remain in the qualitative evaluation, but in the future, imaging is carried out by changing the moisture content of photographing object sample stepwise, and the verification on the quantitative evaluation will be carried out.