Research On The Automatic Generation Method Of Mesh And Shader With Multiple Levels Of Detail

Level of detail(LOD)technique has been widely used as a key rendering optimiza-tion in many graphics applications.Different kinds of LODs,such as geometric LOD or shader LOD,have been exploited to different extents.Numerous approaches have been proposed to automatically generate these LODs.However,none of them have consid-ered simplifying the geometry and shader at the same time.In this paper,we explore the observation that both of simplifications on geometric and shading details result in visual fidelity of appearance,therefore can be done in a joint manner.We present a new discrete multi-resolution representation of an object,the mesh and shader LOD.Each less detailed representation is not only a simplified mesh or a simplified shader,but could be of both simplified versions.To create such LODs,we propose a new automatic algorithm that adaptively places levels at different distances as well as optimizes best-simplified mesh and shader at each level.There are three main steps in this algorithm,which are searching optimal shader and mesh pairs at some distance intervals,finding the smoothest LOD path,and optimizing level distribution.To implement the simplifi-cation,we use an image error metric to evaluate the edge collapses on geometry or code simplifications in the shader,and guide the entire optimization at different levels.To take consideration of both mesh and shader simplification at the same time,we firstly propose a brute-force joint simplification method that directly integrates the mesh simplification into shader optimization.Although we can get ideal LOD results via this method,it's too time-consuming to be applied in practice.To accelerate this joint simplification,we utilize the monotonicity of quality loss of increasingly simplified meshes and shaders,and perform a 1D search to find optimal pairs instead of a brute-force search in the space of combinations of simplified meshes and shaders.As for the optimization on the generated LOD,we propose a method of finding the smoothest LOD path with Dijkstra algorithm,which can apparently ease the visual artifacts of level transition.Besides,our level distribution optimization method can make great trade-offs between the rendering performance and the memory usage.Results show that our mesh and shader LOD achieves better performance-quality trade-offs than prior LOD representations,such as only using simplified meshes or shader-s.And our adaptive LOD generation algorithm also shows good applicability among different platforms.