Bidirectional reflectances obtained from optical satellite sensor is effective for the estimation of vegetation quantity (e.g., above ground biomass) because biomass is related to canopy shape and the information of that canopy shape can be obtained by bidirectional reflectance. The relationships between bidirectional reflectance and canopy shape have been modeled in several studies. However, it is extremely difficult to measure the input parameters (e.g., leaf area index, leaf inclination angle) of those models in the field. Therefore, the bidirectional reflectance predicted by those models does not match with the bidirectional reflectance observed over the canopy. On the other hand, the bidirectional reflectance obtained at top of canopy by airborne or spaceborne platform is affected by limited observation geometry. In this study, we developed bidirectional reflectance simulator (BiRS) which can simulate bidirectional reflectance in any arbitrary observation geometry. BiRS can estimate bidirectional reflectance using digital surface model (DSM) and top of canopy bidirectional reflectance obtained by radio controlled helicopter.
A comparison of the rain rate estimated with the assumptions of Rayleigh and Mie scattering is made. We analyzed the different relationships between the radar reflective factor and rain rate (so-called Z-R relationship) with both scattering models for different DSD (droplet size distribution) and rainfall types as the wavelength is 2.2cm which is in accord with the band of TRMM/PR. Meanwhile we introduced a discrete ordinates method to retrieve the Z-R relationship for Mie scattering assumption. It is found that the retrieval result can be represented as the sum of some simple Z-R relationships. By the analysis of the Z-R relationships estimated from Rayleigh and Mie scattering assumptions in the rain types, we found that the difference of Z-R relationships between Rayleigh and Mie scattering in the thunderstorm that represents the larger raindrop size is larger than that in the drizzle that represent the smaller raindrop size.
In this research, an advanced data fusion technology was developed for the purpose of precise/automatic road sign extraction, by fusing collected initial navigation data, stereo images and laser range data. The major contributions of this research are fusion of stereo images and laser range data for high accurate road sign candidate extraction and reducing the misrecognition of road signs by using 3D information and multi-stereo-images. A lot of experiments were performed to certify and check the accuracy and efficiency of our fusion-based precise/automatic road sign extraction technology. From achieved results of these experiments, our developed system is efficient system for generating high-accuracy road sign database.
From the preliminary experiment, we received suggestion that temperature information is useful for diagnosis of water stress of the vegetation. Then, we continued the measurement of water potential, reflectance and temperature change for two sets of sample trees of Viburnum lantana by giving water to one set and cutting the supply of water to the other set. After the water shortage, water potential of the leaf was on the decrease from 12th day. On the other hand, temperature change of leaf was on the increase from 18th day, and NDWI obtained from reflectance was on the decrease from 30th day when the leaf is dying. Therefore, temperature information is more suitable and available for the early diagnosis of the water stress than NDWI.
Convenient 3D measurement using consumer grade digital camera is enormously expected in various fields with appearance of the low cost and high-resolution consumer grade digital cameras. In these circumstances, the authors have been concentrating on developing convenient 3D measurement system which is Image Based Integrated Measurement system called as IBIM system. The device of IBIM system consists of a consumer grade digital camera and laser distance meter. The most remarkable point of the system was its ability to calculate exterior orientation parameters and interior orientation parameters and pseudo GCPs without using scale bar or GCPs in object field. However, there were still issues which are labor and time consuming in distance measurement and deterioration of image quality. In order to achieve more convenient 3D measurement, the IBIM system is improved using triplet images of multiple cameras of different resolutions and bundle of distances. This paper describes camera calibration techniques and its evaluations using images of multiple cameras of different resolutions and bundle of distances.
In this technical report, we propose a new method to extract tree data form airborne laser scanner data by bilateral filter. We prove the effectiveness of the proposed method through experiments which used airborne laser scanner data of river area. Finally, we comment on the respects in which the proposed method is improved and on future prospects.