Alfalfa Growth Simulation Model And Visualized Realization

Based on the crop models and the field experiments in this study, alfalfavegetative morphological characteristics of organs were observed under the differentcultivar and different water conditions, and the growth processes were explored inseveral alfalfa variaties of Gansu. With the effective accumulative temperature as thekey factor of alfalfa growing development, the growth and developmental simulationmodel of the alfalfa leaf and stem were constructed. And then the leaf and stemvisualization of alfalfa were realized, based on constructed morphologic models andon object-oriented Visual C++program platform combining with the Open GL system.Theresults are as follows.(1) The leaf form model was established. Based on the leave test data of differentmoisture conditions and different alfalfa varieties, and through the continuousobservation on leaf length and width as well as leaf area of alfalfa cotyledons,branches leaves, and ternate leaves, the growth process of alfalfa leaf was determinedin accord with S curve. With the Logistic equation, a dynamic growth process modelof the alfalfa leaf was bulit, and then field tests of alfalfa model were carried outthrough the different alfalfa varieties of field test data. The test results showed that theroot mean square error (RMSE) of leaf area, leaf length and leaf width wereseparately at10.3%,9.8%and11.6%(on cotyledons), at9.3%,8.7%and10.5%(onbranch leaves), and at10.2%,9.6%and11.4%(on ternate leaf), and expressed thatthe model simulation value had better alignment to the field data of alfalfa leaves, andthe simulation model also had higher precision and better predictability.(2) The alfalfa stem model was established. After a comprehensive analysiswith the stalk variation during the alfalfa growth process, the alfalfa stem growthcurve was confirmed with S-shape. Based on differenrt moisture conditions, thealfalfa stalk morphological parameters such as plant height, internode length, stemdiameter, branch length, branching, roughness, and the length of the petiole, weresimulated by the Logistic equation simulation model during alfalfa stalkreproductive processes. In the study, the models were verified by the experimentaldata which were obtained from the different alfalfa varieties used. The results showed that the root mean square error (RMSE) of the main stem length, diameter,branch length, diameter, petiole length model and roughness model were separatelyat9.4%,10.3%,8.9%,11.4%,10.8%,13.2%,10.2%,11.6%,9.8%,9.4%,,10.5%whichalso indicated that the alfalfa stem simulated and measured values had a bettergoodness of fit, and that the simulation models had a higher accuracy and a betterpredictability.(3) The afalfa stem curve characteristics were simulated. Because the dynamicsimuation of alfalfa stalks curve characteristics had a great significance for the visualexpression of the growth of alfalfa, the branching stalk of alfalfa was only simulatedand the main stem of the alfalfa was perpendicular to the ground was assumed inorder to reduce the simulation complexity of the stalks curve. By continuousobservation of the alfalfa stalks curve characteristics on different treatmentconditions, the curve equations of the alfalfa branching stalk were derived and built,and parameterization of the influence coefficient and the equation were achieved andsolved. With the help of stereo vision technology, the stalk curve equationsimulations were carried out by the space coordinates data during growth period ofdifferent varieties of alfalfas.（4）The alfalfa leaves and stalks visualization were realized. Based on theshape models of alfalfa leaves and stalks, with the binocular stereo vision technologyto get three-dimensional information of leaves and stalks, a three-dimensionalvisualization model of the alfalfa leaves was established in Visual C++platformwhich combined with open GL functions and NURBS surfaces. Thethree-dimensional visualization model of the petioles, main stem nodes andsub-minor nodes were constructed seperately by the B-spline curve. According to thetopological structure of an alfalfa plant, the three-dimensional visualization modelsof alfalfa leaves with stalks were combined together and the whole alfalfathree-dimensional visualization model was finally built. The visual display effectsshowed that this model had a certain degree of feasibility and practicality.