This paper proposes a new method to simplify mesh in 3D terrain.The 3D terrain is presented by digital elevation model.First,Laplace operator is introduced to calculate sharp degree of mesh point,which indicates the variation trend of the terrain.Through setting a critical value of sharp degree,feature points are selected.Second,critical mesh points are extracted by an recursive process,and constitute the simplified mesh.Third,the algorithm of linear-square interpolation is employed to restore the characteristics of the terrain.Last,the terrain is rendered with color and texture.The experimental results demonstrate that this method can compress data by 16% and the error is lower than 10%.
The building information model/modeling(BIM) technology is currently applied in a broad range of applications and research for facility management(FM), while the BIM-based mobile FM is difficult owing to various factors and environments. For example, the mobile applications usually require frequent cross-equipment compatibility. This paper proposes a reasonable BIM-based FM cross-platform framework and develops a mobile application on the basis of an existing BIM-based FM system. The developed mobile application is applied in a case study of a metro station project in Guangzhou to verify its effectiveness in FM practice. It helps maintenance staff in viewing BIMs, accessing related information, and updating maintenance records in a unique platform. The test results demonstrate that the proposed BIM-based cross-platform framework meet the FM application requirements and supports the extension of FM functions.
In order to reduce nursing intensity and improve freedom of the elderly and the disabled,a multi-function nursing wheelchair which can switch chair to bed and realize many kinds of posture transformation is designed.This paper introduces the mechanical structure design (position adjustment mechanism and variable wheelbase mechanism) and control design of posture transformation unit of multifunctional nursing wheelchair.
In the process of seismic data interpretation,the extraction of a horizon or a fault is generally needed.In this paper we present a fast extraction method.First select some feature points interactively,then reconstruct the surface according to the selected feature points by using B-spline interpolation curve or surface.In order to solve the error-drawing problem appeared in the process of interactive rendering,which is caused by the change of sampling interval as the view point changes,we combine shear-warp and splatting algorithm to render the surface.The rendering of seismic data and specific surface in our work are achieved on GPU platform using CUDA programming language,which make it able to meet the requirements of real-time rendering.
