A fast and reliable method for the delineation of tree crown outlines for the computation of crown openness values and other crown parameters

2011 ◽  
Vol 41 (9) ◽  
pp. 1827-1835 ◽  
Author(s):  
Frédéric Boivin ◽  
Alain Paquette ◽  
Pierre Racine ◽  
Christian Messier
Keyword(s):  
Hybrid Poplar ◽  
Computer Assisted ◽  
Tree Crown ◽  
Area Index ◽  
Tree Crowns ◽  
Mixedwood Forests ◽  
Poplar Trees ◽  
Crown Shyness ◽  
Parameter Values

Numerous crown parameters (e.g., leaf area index, diameter, height, volume) can be obtained via the analysis of tree crown photographs. In all cases, parameter values are functions of the position of the crown outline. However, no standardized method to delineate crowns exists. To explore the effect of different outlines on tree crown descriptors, in this case crown openness (CO), and facilitate the adoption of a standard method free of user bias, we developed the program Crown Delineator that automatically delineates any outline around tree crowns following predetermined sensibility settings. We used different outlines to analyze tree CO in contrasting settings: using saplings from four species in young boreal mixedwood forests and medium-sized hybrid poplar trees from a low-density plantation. In both cases, the estimated CO increases when calculated from a looser outline, which had a strong influence on understory available light simulations using a forest simulator. These results demonstrate that the method used to trace crown outlines is an important step in the determination of CO values. We provide a much-needed computer-assisted solution to help standardize this procedure, which can also be used in many other situations in which the delineation of tree crowns is needed (e.g., competition and crown shyness).

scholarly journals Beitrag des terrestrischen Laserscannings zur Erfassung der Struktur von Baumkronen | Application of terrestrial laser scanning for measuring tree crown structures

2011 ◽  
Vol 162 (6) ◽  
pp. 186-194 ◽  
Author(s):  
Hans Pretzsch ◽  
Stefan Seifert ◽  
Peng Huang
Keyword(s):  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Tree Crown ◽  
Mixed Stands ◽  
Individual Tree ◽  
Area Index ◽  
Tree Crowns ◽  
Crown Structure ◽  
The Individual ◽  
Tree Leaf

This paper addresses the potential of terrestrial laser scanning (TLS) for describing and modelling of tree crown structure and dynamics. We first present a general approach for the metabolic and structural scaling of tree crowns. Out of this approach we emphasize those normalization and scaling parameters which become accessible by TLS. For example we show how the individual tree leaf area index, convex hull, and its space-filling by leaves can be extracted out of laser scan data. This contributes to a theoretical and empirical substantiation of crown structure models which were missing so far for e.g. quantification of structural and species diversity in forest stands, inventory of crown biomass, species detection by remote sensing, and understanding of self- and alien-thinning in pure and mixed stands. Up to now works on this topic delivered a rather scattered empirical knowledge mainly by single inventories of trees and stands. In contrast, we recommend to start with a model approach, and to complete existing data with repeated TLS inventories in order to come to a consistent and theoretically based model of tree crowns.

Computer-Assisted High-Re Solution TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 162-163
Author(s):  
F.A. Ponce ◽  
H. Hikashi
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Computer Software ◽  
Video Camera ◽  
Image Contrast ◽  
Objective Lens ◽  
Computer Assisted ◽  
Optical Parameters ◽  
Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

scholarly journals Effect of data quality on estimates of farm infectiousness trends in the UK 2001 foot-and-mouth disease epidemic

2006 ◽  
Vol 4 (13) ◽  
pp. 235-241 ◽  
Author(s):  
Nicholas J Savill ◽  
Darren J Shaw ◽  
Rob Deardon ◽  
Michael J Tildesley ◽  
Matthew J Keeling ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Data Quality ◽  
Foot And Mouth Disease ◽  
Mouth Disease ◽  
Inaccurate Data ◽  
Foot And Mouth ◽  
The Uk ◽  
Parameter Values

Most of the mathematical models that were developed to study the UK 2001 foot-and-mouth disease epidemic assumed that the infectiousness of infected premises was constant over their infectious periods. However, there is some controversy over whether this assumption is appropriate. Uncertainty about which farm infected which in 2001 means that the only method to determine if there were trends in farm infectiousness is the fitting of mechanistic mathematical models to the epidemic data. The parameter values that are estimated using this technique, however, may be influenced by missing and inaccurate data. In particular to the UK 2001 epidemic, this includes unreported infectives, inaccurate farm infection dates and unknown farm latent periods. Here, we show that such data degradation prevents successful determination of trends in farm infectiousness.

Groundwater Capture Using Hybrid Poplar Trees: Evaluation of a System in Ogden, Utah

2001 ◽  
Vol 3 (1) ◽  
pp. 87-104 ◽  
Author(s):  
A. Ferro ◽  
J. Chard ◽  
R. Kjelgren ◽  
B. Chard ◽  
D. Turner ◽  
...  
Keyword(s):  
Hybrid Poplar ◽  
Poplar Trees

Determination of the tertiary structure of glycoprotein hormones by computer-assisted modelling of hCG

1986 ◽  
Vol 113 (1_Suppl) ◽  
pp. S134-S135
Author(s):  
K.P. WILLEY ◽  
M. R. LUCK ◽  
F. LEIDENBERGER
Keyword(s):  
Tertiary Structure ◽  
Computer Assisted ◽  
Glycoprotein Hormones

scholarly journals Comparative Study of Optimization Algorithms for The Optimal Reservoir Operation

2018 ◽  
Vol 246 ◽  
pp. 01003
Author(s):  
Xinyuan Liu ◽  
Yonghui Zhu ◽  
Lingyun Li ◽  
Lu Chen
Keyword(s):  
Reservoir Operation ◽  
Optimization Problems ◽  
Optimization Algorithms ◽  
Complex Problem ◽  
Optimization Techniques ◽  
Decision Variables ◽  
Handling Methods ◽  
Optimality Algorithm ◽  
Parameter Values

Apart from traditional optimization techniques, e.g. progressive optimality algorithm (POA), modern intelligence algorithms, like genetic algorithms, differential evolution have been widely used to solve optimization problems. This paper deals with comparative analysis of POA, GA and DE and their applications in a reservoir operation problem. The results show that both GA and DES are feasible to reservoir operation optimization, but they display different features. GA and DE have many parameters and are difficult in determination of these parameter values. For simple problems with mall number of decision variables, GA and DE are better than POA when adopting appropriate parameter values and constraint handling methods. But for complex problem with large number of variables, POA combined with simplex method are much superior to GA and DE in time-assuming and quality of optimal solutions. This study helps to select proper optimization algorithms and parameter values in reservoir operation.

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