Detecting Phenophases of Subarctic Shrub Canopies by Using Automated Reflectance Measurements

Estimating Paddy Rice Leaf Area Index with Fixed Point Continuous Observation of Near Infrared Reflectance Using a Calibrated Digital Camera

“…As the system continuously measures refl ectance, even if the observed area is rather restricted, it may help compensate satellite or airborne remote sensing when weather conditions prohibit a satellite or airplane from taking timely images for specific objectives. To monitor phenological changes in a forest, we installed weatherproof spectroradiometers and/or digital cameras with fisheye lenses on towers (Shibayama et al, 1999;Hilker et al, 2007;Nishida, 2007;Richardson et al, 2007). However, there have been few studies on automatically estimating and recording seasonally continuous visible and near infrared narrow band reflectance images for crop canopies.…”

“…To overcome the instability of solar irradiance, we devised a two-band digital camera enclosed in a waterproof housing, combined with solar irradiance sensors, for collecting as many images as possible during the daytime regardless of the time and weather conditions. An imaging device such as a digital camera, instead of a non-imaging, unified-field-of-view radiometer, allows instantaneous and multiple-site observations without mechanical movement of the sensor (Kharuk et al, 1992;Shibayama et al, 1999). To reduce equipment costs, we used low-price pocket cameras converted into a two-band imaging device.…”

Seasonal reflectance trends of hemiboreal birch forests

“…Unfortunately, there is very little empirical data (e.g. Miller et al, 1997;Shibayama et al, 1999) on the seasonal reflectance trajectories of boreal understory species that our simulated trajectories could be compared to. However, on the qualitative level, our results agree with their conclusions: differences in the understory reflectance of different site fertility types increase towards midsummer and the NIR spectral channel is the most dynamic in detecting growth stages of plants.…”

Continuous Monitoring of Visible and Near-Infrared Band Reflectance from a Rice Paddy for Determining Nitrogen Uptake Using Digital Cameras

“…Corresponding to such requirements, an automated weatherproof spectral radiometer attached to a rotating arm has been proposed and devised for long-term continuous observations (Shibayama et al, 1999), but it will be costly to target multiple sites for many years. Ground-based acquisition of spectral images may partly resolve the problem since it should simultaneously collect the spatial distribution of the widespread target.…”