Clustering and merging for real-time forest rendering 免费阅读 下载全文 Rendering of large-scale forest scenes is a challenging task,whose highly geometric complexity will put heavy burden on current graphics hardware.When navigating the scene,the overall visual result is generally considered as the core concern.A new method is proposed in this paper for large-scale forest rendering using clustering and merging strategies.Our method improves the rendering effect by clustering polygons according to the point information with relation to neighbours.A fast forest rendering system is developed accordingly.The relative techniques in the system can improve the visual quality on demand of different applications.
The automatic height extraction of buildings from shadow region 免费阅读 下载全文 Height extraction for buildings is a fundamental step of 3D scene reconstruction in many virtual reality applications.In this paper,we propose an automatic method to extract the height of buildings in high resolution satellite imagery based on the length of shadow.Taking into account the limitation of traditional algorithms,we make use of the boundary information of a building to facilitate detecting and matching the shadow regions with higher accuracy.Then,we introduce a shadow-cast model to correct the shadow location in our system.The experimental result shows that when extracting the height of buildings from complex urban regions,our method has better accuracy.
A visualized presentation method of Muqam music inheritance regions based on SVG 免费阅读 下载全文 Sinkiang Muqam music,which is a combination of song,dance,music,folk-custom and literature,is in the list of World Intangible Cultural Heritage.It is distributed in different regions in Sinkiang.Because of the different inheritance regions as well as the different influence of history and culture,there formed Muqam music of different region style,further presented different artistic style.This article presents a method to intuitively show the inheritance distribution of four kinds of Muqam music in Sinkiang based on scalable vector graphics technology,it provides methods and tools of visualization research on the protection and inheritance of Muqam music.
Image interpolation algorithm on a triangular grid 免费阅读 下载全文 A new method for constructing a fitting surface on a triangular grid is presented.Assuming images are obtained by sampling from the original scene.Conventional polynomial interpolation methods generally construct the fitting surface on a square grid.Different from existing methods,the new method constructs the fitting surface on a triangular grid which can divide the original surface more detailed and improve approximation accuracy.As the quality of the image edges plays a key role in visual effects of image,the new method uses image edges as constraints to get a triangle grid.The new method constructs a cubic polynomial patch locally using image data to approximate the original surface.Experimental comparison results of the new method with other methods show that the new method can produce high-quality images and remove the zigzagging artifact.
An explicit fairing indicator for 2D curves 免费阅读 下载全文 Resorting to cubic spline function instead of parametric spline representation,an explicit fairness indicator and an efficient fairing algorithm for 2D curves are presented.The input point sequence is firstly partitioned into several overlapped function segments.For each segment,a cubic spline function is used as the representation tool which entails a polyline approximation of curvature plot.Based on the extrinsic relationship between the polyline and the positions of data points,a coarse-to-fine faring method is proposed which efficiently identifies and eliminates the unnecessary inflection points.Our algorithm generates the best results to date,which is validated by numerous practical examples.
The G3 spline basis functions 免费阅读 下载全文 The explicit expression of the G~3 basis function is presented in this paper.It is derived by constructing the conversion matrix between G~3 basis function and Bézier representation.After the matrix decomposition,equations for constructing G~3 splines can be presented independently of geometric shape parameters’ values.It makes the equation’s solving easier.It is also known that the general form of the G~3 spline basis function is given in the first time.Its geometric construction method is presented.
Density-controlled Delaunay triangulation for 2D sea area 免费阅读 下载全文 Triangulation is widely used in scientific research,such as finite element mesh generation,surface reconstruction and the reconstruction of the density field data.This paper proposes a new method combining image processing and density-controlled Centroidal Voronoi tessellations to quickly generate a density-controlled constrained Delaunay triangulation for 2D sea area.Firstly,preprocess digital images of the sea area and extract the boundary of seawater region by eight-neighbor searching algorithm.Then,I use "Odd-Even Testing" method to check if one random vertex is inside the boundary and insert random vertices into the boundary.Finally,we get the CDT of random vertices by density-controlled CVT-Lloyd method.We also give some comparisons with existing methods,and our method performs better in final result of triangulation.
Disassembly sequence planning using component-joint graph and ant colony optimization 免费阅读 下载全文 Disassembly sequence planning is an important step of mechanical maintenance.This article presents an integrated study about the generation and optimizing algorithm of the disassembly sequence.Mechanical products are divided into two categories of components and connectors.The article uses component-joint graph to represent assembly constraints,including the incidence constraints are represented by incidence matrix and the interference constraints are represented by interference constraints.The inspiring factor and pheromone matrix are calculated according to assembly constraints.Then the ant generates its own disassembly sequences one by one and updates the inspiring factor and pheromone matrix.After all iterations,the best disassembly sequence planning of components and connectors are given.Finally,an application instance of the disassembly sequence of the jack is presented to illustrate the validity of this method.
A mobile application framework of the BIM-based facility management system under the cross-platform structure 免费阅读 下载全文 The building information model/modeling(BIM) technology is currently applied in a broad range of applications and research for facility management,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.