Research On Surface Fitting And Visualization Of Dam

This paper is aimed at the shorts of the display of data reprocessing gotten from finite element analysis of dam to research and discuss.When researchers design,analyze dam and maintain dam in after stage,they hope to visualize the shape of dam surface and the accurate position of surface points straightly.The image used through traditional way of linking between element faces showed an incondite effect and have some differences from actual dam surface because of the plane element faces. Additionally,the connection between element vertexes is straight line,not fitting curve,the nephogram display of 3D field information is incomplete and inaccurate to some extent. Though there are so many algorithms to fit surface,the fitting surfaces using most of those algorithms do not pass the data point on the surface.Those algorithms don't have applicative value and significances.What is more,researchers want to watch the information distribution of dam 3D field data using a multi-angle mode from the whole dam,which involves the display method of inner information.The means using cutting surface can realize it.However,it can only show the single section 3D field data information as opposed to show the whole dam.Using volume rendering techniques can achieve this purpose.Nevertheless, volume rendering techniques have some deficiencies,like great amount of calculation and high demand of hardware,which affect the velocity of image rendering.It is valuable to research on volume rendering methods to find a way that can not only drawing quickly but also satisfy the need of engineering.For those reason up above,this paper carries out research and discuss around the aspects of algorithms of fitting curve and surface,realistic representation methods,surface rendering methods and volume rendering methods.Firstly,through discussing and comparing the existing fitting curve and face algorithms, taking the advantage of interpolation spline passing the data points,this paper researches on fitting methods of interpolation spline and surface and puts a fitting algorithm formula of cubic interpolation surface.By using it,we can realize the net surface display of dam and pick up points from dam surface accurately.As the results shows,this algorithm is easy to implement and save memory and calculating time.Fitting surface using this way link smoothly and continuously which nearly show the actual dam appearance shape.It will have a good application prospect. Secondly,based on the cubic interpolation surface fitting algorithm,this paper research the method to display the realistic representation of dam surface and method of surface rendering to display 3D field of dam surface further.Then this paper achieve the purpose of dam surface realistic representation display and accurate show of field value.From the results of display,surface is continuous and smooth and has a good realistic representation.In the meanwhile,along with the increase of subdivision interval,the precision of data fitting is upgrade as well which is useful to realize picking points and their field value of dam surface arbitrarily and accurately.Not only in the aspect of finite element analysis of dam,but also in aspect of every field,such as surface modeling,surface realistic representation,picking points from surface arbitrarily and accurately,development and improvement of finite analysis software and so on,this method will be applied in a wide range.Last but not least,volume rendering is one of the hot spots of visualization in scientific computing presently.Through the development of nearly thirty years,volume rendering techniques formed numerous algorithms and accelerating methods.By the way of summarizing and discussing various kinds of volume rendering means and algorithms, combining the actual engineering application,this paper selects relative cell projection method and optimizes its display method.In the end,this paper displays the inner information and multi-angle observing 3D field of dam dynamically.