The Study Of Visual Simulation Technique Of Interactive Stand Management In Plantations

Improving the ability of forestry informatization management in order to serve modernforestry is important work in the field of forestry science and management practices nowadays.The analysis and research of forest growth changes, forest structure characteristics and forestmanagement measures have a significant role of maximizing the multiple benefits of forestecosystem. Based on the theory of forest management and adapting to the needs of modernforestry construction, the visual simulation technology is applied to the forest management soas to improve the forest growth simulation accuracy, enhance the understanding and awarenessof forest structure and promote the forest management decision making ability by using thevisual mode. As a result, it can provide a new method for solving problems in the modernforest management and achieving forest informatization efficient management, and thenimprove the forestry informatization management level.Combined the theory and practice of stand management and computer visualization andsimulation technology, the visual simulation technique of interactive stand management inplantations and a visual simulation system that was faced the managers and could achieve standmanagement objectives using quantitative methods were proposed in this study in order toprovide the managers with technical support of grasping stand real-time and dynamic changesand managing stands. All test data that included three Chinese fir plantations and one mixedplantation of Chinese fir and masson pine were collected in Huangfengqiao state-owned forestfarm of Youxian, Hunan. The major work and results are as following.(1) Visual simulation method of stand growth based on self-defined growth modelsparametersFirst of all, the model library with unknown parameters was build and the calculationmethods of model variables were packaged. Secondly, based on developing graphical standgrowth activities, growth models were stored successfully by using the interface of custom parameters. Finally, the reading and analytical methods of models were proposed andcombined with the visual simulation method of stand growth so as to provide the basis for thefollow-up visual simulation of stand growth. By using this method, managers can definemodels parameters by human-computer interaction. So, this method can provide technicalsupport for defining mathematical models that apply to the local law of stand growth, canensure the precision of models and can provide a new idea for improving the accuracy of visualsimulation of stand growth.(2) Visual simulation technique of the interaction process among stand growth, standstructure and stand managementIn the first place, after combing stand management practices, referring to determinationmethods of main technical indexes, and proposing7decision making factors for removingtrees, we developed21graphical related activities by using WF, which contained6management measures-pruning, thinning, selection cutting, shelterwood cutting, clear cuttingand regeneration cutting,1stand growth activity,1stand structure analysis activity,7decisionmaking activities for removing trees and6other related activities, and then the visual model ofthe condition judgment of management measures and3types of decision making visualizationmodels for removed trees were build. In the next place, by defining the workflow runtimeengine and adding tracking services of user-defined activities, the visual simulation of theinteraction process among stand growth, stand structure and stand management was executed.In the end, using GDI+technique and MOGRE rendering engine, the visual simulation ofstand status at2-dimension (2D) and3-dimension (3D) was implemented before and afterstand management. A case study of accretion cutting in a Chinese fir plantation was carried out.The results showed that in the manager-oriented visual workflow designer, this method enabledmanagers to create the flow model of the interaction process among stand growth, standstructure and stand management by dragging and defining activities, and that the interactionprocess could be simulated visually. (3) Visual simulation technique of decision making of interactive stand managementmethodsSummarizing stand management targets and selecting decision making policies-cuttingvolume, crown density, average DBH, mingling, etc., which were packaged the attributes of thedecision making activity, we developed the decision making activity of interactive standmanagement methods. When the implementation of the decision making activity ofmanagement methods was analyzed, the decision making model of interactive standmanagement methods was built and the decision making of interactive stand managementmethods was simulated visually. The decision making of accretion cutting methods in aChinese fir plantation was taken as an example in order to select the better method. The resultsshowed that this method could select one specific method closer to the management target froma variety of methods according to the decision making policy-cutting volume and then itcould be simulated visually, and that the whole process could meet the demands of forestmanagement practices.(4) Visual simulation technique of interactive stand management measures activities basedon a stand virtual environmentBased on direct3D rendering techniques, the geometric modeling method, the trunksimulated through two truncated cones, branchs simulated through two quadrilaterals with afolding angle and the spatial distribution of branches controlled by the crown shape curve, theparameterized model of individual trees was developed, which included the parameters-DBH,height, crown height, crown width, under-branch height, crown shape, etc., and then the modelwas stored as a mesh file which contained78submeshes. In the stand scene built by using theMOGRE rendering engine, the interactive tree cutting process and the interactive pruningprocess were simulated visually based on the ray query algorithm and the ray query algorithmthat can detect the triangular surface. The Chinese fir plantation was taken as an example tocarry out the simulation test. The results showed that the tree’s3D model that included multipletree measurement factors could be built fast by using the parameterized modeling method of individual trees, and that the processes of interactive tree cutting and interactive pruning weresimulated vividly and intuitively. In a stand virtual environment, managers can accuratelyselect the removed and pruned trees, so interactive capabilities between managers and the standvirtual environment are enhanced. Meanwhile, this method can provide another feasible way ofcarring out stand management measures.(5) Design and application of visual simulation system of interactive stand management inplantationsOn the basis of the technical methods, models and algorithms proposed in this study, thevisual simulation system of interactive stand management in plantations was developed. Thesingle tree selection felling was taken as an example in a mixed plantation of Chinese fir andmasson pine in order to apply the system. The results showed that this system with ensuring thesimulation accuracy of stand growth could visually simulate stand growth, analysis of standstructure, implementation of stand management measures and stand environment by usinggraphics and images showed to managers and that this system with strong human-computerinteraction capability, visibility, operability and applicability could be used to establish standmanagement process visualization models, visually simulate interactive stand management inplantations, improve stand management automation capabilities and authentically guide standmanagement practices.The proposal and realization of a set of technical methods can provide methods withhigher technology and an application platform for stand management, supervise the stand inreal time, and significantly improve the stand management ability.