Fumiki Hosoi

Voxel-Based 3-D Modeling of Individual Trees for Estimating Leaf Area Density Using High-Resolution Portable Scanning Lidar

A method for accurate estimation of leaf area density (LAD) and the cumulative leaf area index (LAI) profiles of small trees (Camellia sasanqua and Deutzia crenata) under different conditions was demonstrated, which used precise voxel-based tree models produced by high-resolution portable scanning lidar. In this voxel-based canopy profiling (VCP) method, data for each horizontal layer of the canopy of each tree were collected from symmetrical azimuthal measurement points around the tree using optimally inclined laser beams. The data were then converted into a voxel-based three-dimensional model that reproduced the tree precisely, including within the canopy. This precise voxel model allowed the LAD and LAI of these trees, which have extremely dense and nonrandomly distributed foliage, to be computed by direct counting of the beam-contact frequency in each layer using a point-quadrat method. Corrections for leaf inclination and nonphotosynthetic tissues reduced the estimation error. A beam incident zenith angle near 57.5deg offered a good correction for leaf inclination without knowledge of the actual leaf inclination. Non-photosynthetic tissues were removed by image-processing techniques. The best LAD estimations showed errors of 17% at the minimum horizontal layer thickness and of 0.7% at the maximum thickness. The error of the best LAI estimations was also 0.7%

3-D modeling of tomato canopies using a high-resolution portable scanning lidar for extracting structural information.

In the present study, an attempt was made to produce a precise 3D image of a tomato canopy using a portable high-resolution scanning lidar. The tomato canopy was scanned by the lidar from three positions surrounding it. Through the scanning, the point cloud data of the canopy were obtained and they were co-registered. Then, points corresponding to leaves were extracted and converted into polygon images. From the polygon images, leaf areas were accurately estimated with a mean absolute percent error of 4.6%. Vertical profile of leaf area density (LAD) and leaf area index (LAI) could be also estimated by summing up each leaf area derived from the polygon images. Leaf inclination angle could be also estimated from the 3-D polygon image. It was shown that leaf inclination angles had different values at each part of a leaf.

Estimation and Error Analysis of Woody Canopy Leaf Area Density Profiles Using 3-D Airborne and Ground-Based Scanning Lidar Remote-Sensing Techniques

Vertical profiles of the leaf area density (LAD) of a Japanese zelkova canopy were estimated by combining airborne and portable ground-based light detection and ranging (lidar) data and using a voxel-based canopy profiling method. The profiles obtained by the two types of lidars complemented each other, eliminating blind regions and yielding more accurate LAD profiles than could be obtained by using each type of lidar alone. In the combined results, the mean absolute errors (MAEs) of LAD ranged from 0.20 to 0.42 m2 m-3, and the mean absolute percentage errors (MAPEs) of the leaf area index (LAI) ranged from 22.3% to 27.2%, for ground areas from 4 to 32 m2, respectively. A laser beam coverage index ¿ incorporating the lidars beam settings and a beam attenuation factor was proposed. This index showed general applicability to explain the LAD estimation error for LAD measurements using different types of lidars and with different beam settings. Parts of the LAD profiles that were underestimated even when data from both lidars were combined were interpolated by using a Gaussian function. The interpolation yielded improved results for ground areas of 16 and 32 m2; the respective MAEs of LAD were 0.17 and 0.11 m2 m-3, and the respective MAPEs of LAI were 8.0% and 9.4%. The proposed method improves lidar-derived LAD estimation and is adapted to broadleaved canopies. The index ¿ was tested against an actual canopy scenario and could be used to determine appropriate lidar measurement settings when data from different sources of lidar data are combined to estimate LAD profiles.

3D monitoring spatio–temporal effects of herbicide on a whole plant using combined range and chlorophyll a fluorescence imaging

Spatio-temporal effects of herbicide including 3-(3,4 dichlorophenyl)-1,1-dimethylurea (DCMU) on a whole melon (Cucumis melo L.) plant were three-dimensionally monitored using combined range and chlorophyll a fluorescence imaging. The herbicide was treated to soil in a pot and the changes in chlorophyll a fluorescence images of the plant were captured over time. The time series of chlorophyll fluorescence images were combined with 3D polygon model of the whole plant taken by a high-resolution portable scanning lidar. From the produced 3D chlorophyll fluorescence model, it was observed that the increase of chlorophyll fluorescence appeared along veins of leaves and gradually expanded to mesophylls. In addition, it was found by detailed analysis of the images that the invisible herbicide injury on the mature leaves occurred earlier and more severely than on the young and old leaves. The distance from veins, whole leaf area and leaf inclination influenced the extent of the injury within the leaves. These results indicated difference in uptake of herbicide in the plant from soil depends on structural parameters of leaves and the microenvironments as well as leaf age. The findings showed that 3D monitoring using combined range and chlorophyll a fluorescence imaging can be utilised for understanding spatio-temporal changes of herbicide effects on a whole plant.

3D Confocal Laser Scanning Microscopy for the Analysis of Chlorophyll Fluorescence Parameters of Chloroplasts in Intact Leaf Tissues

We analyzed the chlorophyll fluorescence parameters in a 3D cellular arrangement in vivo by using a modified Nipkow disk-type confocal laser scanning microscope (CLSM). We first defined the 3D values of Phi(PSII) (photochemical yield of PSII) and NPQ (non-photochemical quenching) in mesophyll, epidermal and guard cell chloroplasts from the leaf surface to several tens of microns in depth. We also used this CLSM method to analyze the relationships between actinic light intensity and the chlorophyll fluorescence parameters for Boston fern and broad bean leaf specimens. As the actinic light intensity increased, the mean Phi(PSII) values decreased and the NPQ values increased in all chloroplasts of Boston fern and broad bean leaf. These values differed with cell type and species. The Boston fern chloroplasts had lower Phi(PSII) values than the broad bean chloroplasts, and vice versa for the NPQ values. The Phi(PSII) values of Boston fern chloroplasts decreased in the order mesophyll, epidermal and guard cell chloroplasts. The NPQ values decreased in the order guard cell, mesophyll and epidermal chloroplasts, except at 12 micromol m(-2) s(-1) actinic light, when the mesophyll value was slightly lower than that of the epidermis. The trend in the Phi(PSII) and NPQ values of broad bean mesophyll and guard cell chloroplasts was opposite to that of Boston fern chloroplasts. As 3D CLSM can provide the Phi(PSII) and NPQ values of each chloroplast in a 3D cellular arrangement, this method has potential for investigating differences in the functions of chloroplasts in vivo.

Detecting seasonal change of broad-leaved woody canopy leaf area density profile using 3D portable LIDAR imaging

Seasonal change of vertical leaf area density (LAD) profiles of woody canopy broad-leaved trees (Zelkova serrata [Thunberg] Makino) was estimated using 3D portable scanning light detection and ranging (LIDAR) imaging. First, 3D point cloud data for the canopy were collected using a portable LIDAR in spring, summer, autumn and winter. For data collection, the canopy was evenly scanned by the LIDAR from three positions 10 m above the ground. Next, the vertical LAD profile in each season was computed from the LIDAR data using the voxel-based canopy profiling (VCP) method. For the computation, non-photosynthetic tissues were eliminated using the LIDAR data obtained during winter. Influence of leaf inclination angle (LIA) on LAD estimation was corrected by LIA data measured by a high-resolution portable scanning LIDAR. The resultant profiles showed that LAD values tended to increase at the upper canopy from spring to summer and decrease at the middle and lower canopy from summer to autumn. Moreover, LIDAR-derived LIA distributions were compared among different seasons. LIA showed an even distribution in spring but changed to a planophile distribution in summer. In autumn, the angles in the <30° class decreased and those between the 30 and 40°classes increased.

Direct current to 34.1-Gb/s, 19-Gb/s/cm/sup 3/ low-jitter parallel optical interconnecting module for high-speed memory test systems

A protocol-free parallel optical interconnecting module is introduced as a solution to solve memory test system transmission bottlenecks. The optical transmission system flexibly suited for a memory test system is reviewed and discussed. A parallel optical module capable of transmitting from dc to 34.1Gb/s (4.267 Gb/s /spl times/8 ch) has been developed. A data transmission throughput density per unit volume of 19 Gb/s/cm/sup 3/ is achieved. A random jitter of less than 3-ps root-mean-square is also achieved. Furthermore, high-density optical connector, high-density optical fiber cable, fiber guides, and cable management/reinforcement members suited for mechanical requirements of the memory test system have been developed.

Accurate detection of tree apexes in coniferous canopies from airborne scanning light detection and ranging images based on crown-extraction filtering

We describe crown-extraction (CE) filtering to accurately determine tree apex positions for various coniferous species using an airborne light detection and ranging–derived digital canopy height model (DCHM). This method uses a square mask, with a frame at the edges, that overlaps pixels within the DCHM image; when no pixels touch the frame, the pixel at the center is extracted as a tree-crown pixel. The apex of each tree is determined by choosing the pixel with maximum height from the pixels in the crown. We compared the performance of this method and of two other methods (local-maximum filtering and canopy-segmentation method) for several species. The CE filtering had the most accurate results for most tree species with appropriate mask size selection. The mean omission, commission, and total errors for all tree species were 8.1%, 1.6%, and 9.7%, respectively, for CE filtering. Comparing mask sizes and canopy diameters estimated from the DCHM for each species revealed that the smallest canopy diameter of each species was close to the most appropriate mask size for that species in CE filtering. We also confirmed that the smoothing process used in the DCHM has little effect on the accuracy of CE filtering.

Estimating chlorophyll content and photochemical yield of photosystem II (ΦPSII) using solar-induced chlorophyll fluorescence measurements at different growing stages of attached leaves

An estimation and comparison of chlorophyll content and photochemical yield of photosystem II obtained from solar and artificially induced chlorophyll fluorescence is presented here, along with a new technique to estimate photochemical yield from the solar-induced method.

Estimating 3D Leaf and Stem Shape of Nursery Paprika Plants by a Novel Multi-Camera Photography System

For plant breeding and growth monitoring, accurate measurements of plant structure parameters are very crucial. We have, therefore, developed a high efficiency Multi-Camera Photography (MCP) system combining Multi-View Stereovision (MVS) with the Structure from Motion (SfM) algorithm. In this paper, we measured six variables of nursery paprika plants and investigated the accuracy of 3D models reconstructed from photos taken by four lens types at four different positions. The results demonstrated that error between the estimated and measured values was small, and the root-mean-square errors (RMSE) for leaf width/length and stem height/diameter were 1.65 mm (R2 = 0.98) and 0.57 mm (R2 = 0.99), respectively. The accuracies of the 3D model reconstruction of leaf and stem by a 28-mm lens at the first and third camera positions were the highest, and the number of reconstructed fine-scale 3D model shape surfaces of leaf and stem is the most. The results confirmed the practicability of our new method for the reconstruction of fine-scale plant model and accurate estimation of the plant parameters. They also displayed that our system is a good system for capturing high-resolution 3D images of nursery plants with high efficiency.