Computer Simulation Of Chromaticity Value Of Vegetation Based On The Clamp Model

Vegetation is the most important component in the ecosystem, meanwhile, the most important coverage type of the earthe surface in the world.It interacts with the solar radiation transmission and inflects the cycle of gas, carbon and other substances of the ecosystem,which is an important part of global change. Having completely control of the growth of vegetation provides a very helpful way to understand the different scale of ecosystem.In many countries, scientists carried out a great deal of research and developped different kinds of complexity models to simulate vegetation, the crop particularly, which is closely related to human .According to theoretical models and assumptions used, the canopy models can be divided into four different kinds of trends: turbid medium model, the geometric optics model, mixed model and computer simulation model.In China, scientists mostly focused on resources detection and systematic environmental issues in global-scale in recent years. There is an urgent requirement for remote sense to provide a wide range of situation and dynamic change of vegetation data.Vegetation simulation is quite an effective means of intuitive that it can reflect the real data. However, in many cases, the applicated models have a lot of problems, for example, the involved parameters can not be applied to a wide range of crops; or simulated scenes inconsistent with the real scene. In addition, the issues which is the most needed to be resolved is how to give the true color of the scene. The so-called true color is not the approximate color commonly, but refers to the color of the leaves which interact with sunlight.Chromaticity values, we call it"color"usually, whose characterization or measurement is a very complex discipline. In order to measure it quantitatively, it will relates to a lot of problems ,such as the visual physical, psychological as well as the lighting conditions of visual observation conditions.The selected topic is also conformed to the trend that traditional remote sense transformates to the quantitative one. Quantitative remote sense is a quite new method and technology to obtain the target parameters or characteristics , which is based on priori knowledge and support of computer systems .It uses remote sensors to obtain the electromagnetic information of the surface features quantitatively. As a new method of acquisition and analysis, quantitative remote sense emphasizes the importance of mathematics or physics model ,which will link the target surface to the observation parameters inversion or quantitative projections of certain geo-target parameters. In this article, which is needed to study is how to build relationship between properties of spetral and chromaticity values, which means measured the value of the color quantitatively.The main contents of this paper is as follows:(1) To selecte model to generate the basic scenario which can describe a variety of vegetation canopy universally and commonly, it requires less involed parameters and directly relates a number of parameters in agronomy and remote sense.(2) To load the three-dimensional coordinates of leaves into POV-Ray ray tracing software, then set up lighting and cameras for rendering the scene.(3) In order to achieve realistic results, to embody differences caused by the transmission and reflection , it is needed to judge that when sunlight to reach the leaves ,what occurrenced, reflection or transmission,.(4)To establishes the relationship between spectral properties of leaf and chromaticity value and study how to calculate the color value of the leaves by reflectance or transmittance.Followed the ideas, the results of this paper is as follows:(1) By compared with the other kinds of models, the clamp model is selected to generate the basic scene , which is based on the principle of common and similar to a variety of vegetation. Clamp model, whose full name is The clumped architecture model of plants, which is called vegetation building model, is a model of the true structure. It uses a simple triangle to simulate the leaf, which is characterized by little input parameters, and agriculture is directly related to remote sense applications, as well as the parameters, based on specific vegetation types to be adjusted, with greater flexibility;(2) In order to establish relationship between spectral properties of leaves and chromaticity values ,we measured the leaves of maize infield as an example and measured reflectance and transmittance, then recorded the experimental high of the sun and the azimuth angle for the scenes to prepare for rendering at the time ;(3) To judge whether reflection or transmission occurred in the leaves in this step ,we used unit vector sinusoidal intersection approach , which involves the relationship between the leaf and the sun, as well as the blade and the camera. The specific method for calculating the leaf is one of the first law of the unit vector A, followed by calculation of the leaves and the sun vector B of the unit method, as well as the camera leaves the unit method and vector C, the calculation of the orthogonal AB and AC values. If both are the same, the reflection; the other hand, the transmission;(4) Finally, relationship is established between leaf spectral properties and the chroma value based on principles and theories of the color-related, and then measured through the reflectivity experiments and calculated transmittance of the color value of the leaves. This step also involves a lot of parameters, such as the tristimulus values, spectral power distribution, luminance factor and so on, therefore, the calculation of color values is a quite more complicated process.The results of the analysis can be found: compared to the real scene, the results with observations this article is not only a better way to achieve a practical observation, stable, and efficient real-time the effectiveness of generating, at the same time, eliminating the random error of remote sensing data and useless information brought about by the impact of interference. Vegetation model parameter values and initial value of state variables the effect of re-adjustment will also depend on the choice of parameters to be adjusted. Be transferred if the parameters are not too many, given the smaller range, the better the adjustment. Therefore, it is an ideal vegetation simulation methods based on data of remote sensing,Color, originally belonging to the scope of physics.Because of its breadth and diversity of applications, it becomes an independent discipline finally, which is known as the chromaticity. However, only the procession of rom the spectral properties of value to the chromaticity color is positivly realized. In addition,it is worth mentioning that the color value, not only merely the frequency of light reflection in the eyes, but also involves the internal structure of leaves and its biochemical parameters, such as water, chlorophyll, carrot Su-such. Leaves in different growth period, the internal content of the different substances will cause the leaves to change color values. There is a very good description for the situation, called prospect model. It is a flat-panel model based on Allen's radiative transfer model, it can express optical properties of leaves from 4,00 nm to 2500nm. Its main parameters include the refractive index n spectra and leaf mesophyll structure parameter N, pigment concentration of Ca + b, and the corresponding water content Cw the specific spectral absorption coefficient (Ka + b and Kw), the adoption of this model given a certain degree of the accuracy of the leaf reflectance and transmission characteristics. Combination of this model, once the inversion become ture, the color values through direct access to the internal parameters of vegetation is also possible. This large-scale simulation master the growth rules of vegetation is very significant. For the complex nature of the vegetation structure and the random distribution of growth, to define and descrip vegetation structure, quantitative characterization would be a very effective and powerful tool.