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1.
模拟绘画的三维几何纹理生成研究   总被引:3,自引:0,他引:3  
该文提出一种模拟绘画的三维几何纹理生成方法。该方法的主要思想如下:(1)对物体表面进行近似等距离分点;(2)假设在各分点处放置一个个小球,利用这些小球来获得物体表面的总体明暗信息;(3)建立各分点处画元的绘制模式;(4)在绘制阶段,利用所获得的光照信息和画元的绘制模式在各分点处绘制画元,以获得符合物体表面总体明暗调子的几何纹理;(5)在上述工作的基础上,通过对画元实施一系列操作来获得更为复杂的几何纹理。与传统方法相比,该文所给出的几何纹理生成技术具有对信息处理的同一性、可对画面信息进行离散处理、所生成的纹理更具立体感和速度快等特性。实验结果验证了方法的有效性。  相似文献   

2.
盛斌  吴恩华 《软件学报》2008,19(7):1806-1816
首先推导与归纳了图像三维变换中像素深度场的变换规律,同时提出了基于深度场和极线原则的像素可见性别方法,根据上述理论和方法,提出一种基于深度图像的建模与绘制(image-based modeling and rendering,简称IBMR)技术,称为虚平面映射.该技术可以基于图像空间内任意视点对场景进行绘制.绘制时,先在场景中根据视线建立若干虚拟平面,将源深度图像中的像素转换到虚平面上,然后通过对虚平面上像素的中间变换,将虚平面转换成平面纹理,再利用虚平面的相互拼接,将视点的成像以平面纹理映射的方式完成.新方法还能在深度图像内侧,基于当前视点快速获得该视点的全景图,从而实现视点的实时漫游.新方法视点运动空间大、存储需求小,且可以发挥图形硬件的纹理映射功能,并能表现物体表面的三维凹凸细节和成像视差效果,克服了此前类似算法的局限和不足.  相似文献   

3.
基于Wang Tiles的几何纹理合成   总被引:1,自引:0,他引:1       下载免费PDF全文
韩建伟  王青  周昆  鲍虎军 《软件学报》2009,20(12):3254-3264
提出了一种基于Wang Tiles的几何纹理合成方法来在不同物体表面上即时地生成几何纹理.首先根据给定的几何纹理预计算出一组Wang Tiles,然后用这组Wang Tiles在不同的目标物体上即时生成新的几何纹理.尽管基于Wang Tiles的方法已经应用于图像纹理,但由于几何纹理采用了与图像纹理完全不同的表示方式,因此需要用完全不同的方法来处理.采用了基于约束的几何纹理合成技术自动生成几何纹理Wang Tiles,从而保证了生成的几何纹理Wang Tiles在所有排列下都能保持其几何连续性.与现有的方法相比,生成的几何纹理Wang Tiles可以重用到不同的目标物体上,同时占用的存储空间及计算量更小,速度更快.  相似文献   

4.
提出一种消除物体表面纹理接缝,重建高精度真实感三维模型的纹理融合方法.首先将不同视场的深度图像匹配到同一坐标系下,经过深度图像融合获得物体完整的几何模型;然后确定深度图像和纹理图像的映射关系,并定义复合权重进行纹理融合来获取整个纹理映射图,并进行模型的纹理映射.该方法可消除物体表面重叠区域由于光照变化、几何模型的非完全漫反射以及拍摄视场的改变等外界因素引起的色彩差异,重构真实感三维模型;且对物体的几何形状、拍摄视场没有限制,能够自由拍摄,并实现高精度三维纹理模型.实验结果表明,文中方法是有效和鲁棒的.  相似文献   

5.
基于结构光的三维测量及重建技术   总被引:3,自引:0,他引:3  
本文介绍了利用结构光实现三维信息获取和重建的方法。该方法是利用结构光和CCD摄像机构成的视觉系统对物体扫描,获取物体可视表面的相对三维坐标,建立不同视点下物体可视域的三维描述。通过对这些离散三维描述的拟合,获得寒带的物体三维描述,建立该物体的几何模型。该技术对拟实制造、仿真加工等应用领域具有重要的意义。  相似文献   

6.
基于几何模型与照片序列的不规则物体纹理获取   总被引:6,自引:0,他引:6       下载免费PDF全文
虚拟世界的建造过程中 ,获取不规则物体的纹理非常重要 .针对数字文物保存与展示的要求 ,提出了一种基于物体单色几何模型及在其周围环绕拍摄的照片序列来获取不规则物体圆柱纹理的算法 .该算法分为投影变换、变形和拼接等步骤 ,通过将物体照片序列上的色彩映射到圆柱贴图面上来获得该物体的纹理 .该算法具有对原始照片质量要求低和允许运行时进行编辑等优点  相似文献   

7.
三维GIS中多分辨率纹理模型的研究   总被引:7,自引:0,他引:7       下载免费PDF全文
在三维地理信息系统 (GIS)中 ,影像数据作为模型表面的纹理特征 ,对弥补复杂模型的几何特性以及提高三维显示的效果具有十分重要的意义 .为了提高三维模型显示的速度和效果 ,以及为了降低纹理贴图时 ,影像的数据量 ,提出了一种与观察视点相关的动态多分辨纹理模型 ,并设计了相应的数据结构用于管理纹理数据 ,另外在讨论观察视点与纹理分辨率之间关系的基础上 ,开发了基于视点的确定纹理分辨率的算法 ,以用于交互三维显示时的纹理映射 ,最后给出了部分实验结果 .实验结果表明 ,多分辨率纹理模型的映射机制可以取得较好的可视化效果 .  相似文献   

8.
采用非均匀纹理层的短毛实时绘制   总被引:5,自引:0,他引:5  
提出一种采用非均匀纹理层来实时绘制真实感短毛的方法,通过混合绘制多层次半透明纹理层来表示物体表面的毛发效果,根据视点位置以及物体表面各部位毛发形态的不同,自适应地采用不同的层数来表示物体各部位的毛发.这种非均匀层数的方式可以在保证绘制质量的情况下尽量减少绘制的面片数,从而加快绘制速度.该方法对中等规模的模型达到了实时的处理速度,并可以有效地表现物体表面的局部性长毛或倒伏毛发等各式毛发形态.  相似文献   

9.
视差映射技术可以通过沿着视点方向平移纹理坐标来实现纹理图像的真实感绘制,然而不正确的纹理坐标偏移量将导致纹理图像的滑动现象.根据视差映射技术原理,通过定义纹理坐标值与高度值之间的映射函数得到偏移量与当前视点坐标的对应关系;利用GPU技术计算得到正确的纹理坐标偏移量,使得在视点动态变换时纹理图像的绘制不会产生滑动现象.实验结果表明,与传统视差映射方法及现有GPU技术校正纹理坐标偏移量方法相比,在没有增加算法复杂度的前提下,采用文中方法可改善纹理图像真实感绘制的效果.  相似文献   

10.
刘星明  蔡铁  王辉静  彭刚  桂荣枝 《计算机科学》2016,43(Z11):256-258, 274
空间曲面的三维数字化测量在工业检测、虚拟现实、影视艺术以及文物保护等领域具有重要的应用价值。提出一种实现自由曲面三维数字化的方法,该方法不仅能重建物体的几何模型,而且能实现物体表面色彩等纹理属性的恢复。利用结构光照明重建空间三维点云数据,并利用匹配算法建立物体的几何模型;然后通过交互式选取点优化策略进行纹理映射的方法实现目标物体的真实感三维重建。与传统的方法相比,该方法能够精确地实现目标物体的纹理重建,避免了特征检测困难或粘贴标准点等方法的数据处理困难以及后期数据的人工等操作,实验结果也验证了该方法的有效性。  相似文献   

11.
Texture mapping has become an essential tool in any synthetic rendering scheme that aims at photorealism. Texture mapping typically associates any point on the surface of the rendered object with a location in the texture space. The surface point is then assigned rendering attributes, such as color or translucency from the respective location found in the texture space. Texture mapping techniques have also been used in attempts to emulate highly detailed geometry on the surfaces of objects. The proposed surface detail synthesis approach closes the loop from modeling to rendering using computer graphics texture mapping techniques, bringing them back into the geometric modeling phase. This article focuses primarily on texturing techniques that relate to shape modeling and surface geometry alteration.  相似文献   

12.
Texture mapping is an efficient and effective tool in computer graphics and animation. While computationally very cost-effective, texture mapping may produce non-realistic appearances of shapes in 3D environment, especially when viewing closely. To improve the realism of 3D modeling, bump mapping technique is developed to add details with the 3D models on top of texture mapping. Bump mapping, however, offers only simple and visual enhancement. Displacement mapping technique can further improve the localized detail of geometry. In this paper, Monge mapping technique is developed for detail and local shape modification of NURBS represented geometry in a 3D environment. Based on multiresolution and refinement schemes, Hierarchical NURBS (H-NURBS) is first investigated to design a mechanism for the purpose of carrying localized geometric information. Monge mapping on H-NURBS patch can be easily performed via simple cut-and-paste operation. Parametric control of the local shapes is developed to facilitate easier and better 3D local modeling.  相似文献   

13.
We present a geometric framework for automatically finding intrinsic correspondence between three-dimensional nonrigid objects. We model object deformation as near isometries and find the correspondence as the minimum-distortion mapping. A generalization of multidimensional scaling is used as the numerical core of our approach. As a result, we obtain the possibility to manipulate the extrinsic geometry and the texture of the objects as vectors in a linear space. We demonstrate our method on the problems of expression-invariant texture mapping onto an animated three-dimensional face, expression exaggeration, morphing between faces, and virtual body painting.  相似文献   

14.
15.
State of the art multiresolution modeling allows to selectively refine a coarse mesh of an object on the visually important parts. In this way it is possible to render the geometry of a given object accurately with a minimum number of triangles. The criteria used in current approaches take care of geometric error and even of shading errors. If however texture mapping is used it is inevitable to control displacements and distortions of the texture during refinements.  相似文献   

16.
In the process of digitizing the geometry and appearance of 3D objects, texture registration is a necessary step that solves the 2D–3D mapping between the 2D texture images and the 3D geometric model. For evaluation of texture registration with ground truth, accurate datasets can be obtained with a complex setup consisting of calibrated geometry and texture capture devices. We do not have any knowledge of such evaluation performed; current evaluations reflect, at their best, the precision achieved by the algorithms, but fail to identify a possible bias. We propose a new evaluation measure based on the epipolar geometry of texture image pairs, with the advantage that the ground truth can be extracted solely from the texture images, independent of the 3D acquisition. We developed a noise model suitable to our purpose and analysed three distance measures based on epipolar geometry, well known in the computer vision community, to find new theoretical and experimental results. Finally, using the proposed framework, we evaluated a texture registration algorithm based on mutual information and found that its accuracy was under half-pixel.  相似文献   

17.
为了克服传统的照片图像拼接方法中利用特征线进行不同照片之间公共交界线定位不准确的缺点,提出一种"几何模型切分"的人脸纹理图像生成算法。通过对人脸几何模型进行切分,以切分后模型图片的轮廓作为边界线裁剪相应的人脸照片,实现不同照片之间交界线的准确对接,并采用柱面纹理映射方法将生成的纹理图像映射到特定人脸几何模型上。实验结果表明,采用提出的"几何模型切分"算法生成的人脸纹理图像进行纹理映射可以得到较好的真实感三维人脸模型,是一种生成人脸纹理图像的有效方法。  相似文献   

18.
In this paper, we present a new method to synthesize geometric texture details on an arbitrary surface from a sample texture patch. The key idea is to use Laplacian texture images to represent geometric texture details, which in turn facilitate simple and effective geometry texture synthesis and enable flexible geometry texture editing. Given a sample model and a target model, we first select a patch from the sample model and extract the geometric texture details. Next, we construct a Laplacian texture imag...  相似文献   

19.
This paper presents a novel approach for appearance and geometry completion over point-sampled geometry. Based on the result of surface clustering and a given texture sample, we define a global texture energy function on the point set surface for direct texture synthesis. The color texture completion is performed by minimizing a constrained global energy using the existing surface texture on the surface as the input texture sample. We convert the problem of context-based geometry completion into a task of texture completion on the surface. The geometric detail is then peeled and converted into a piece of signed gray-scale texture on the base surface of the point set surface. We fill the holes on the base surface by smoothed extrapolation and the geometric details over these patches are reconstructed by a process of gray-scale texture completion. Experiments show that our method is flexible, efficient and easy to implement. It provides a practical texture synthesis and geometry completion tool for 3D point set surfaces.  相似文献   

20.
Striving for photorealism, texture mapping, and its more advanced variations, bump and displacement mapping, have all become fundamental tools in computer graphics. Recently, the introduction of programmable graphics hardware has enabled the employment of displacement mapping in real-time applications. While displacement mapping facilitates the actual modification of the underlying geometry, it is constrained by being an injective mapping. Further, it is also limited because it usually maps the geometry of the (low-resolution) smooth base surfaces, typically by displacing their vertices. Drawing from recent work on deformation displacement mapping (DDM) [4], in this paper we offer real-time solutions to both these limitations. Our solutions make it possible to employ the DDM paradigm on programmable graphics hardware. By reversing the roles of the base surfaces and their geometric details, both the one-to-one constraint and the base surface resolution limitation are resolved. Furthermore, this role reversal also paves the way for other benefits such as a tremendous decrease in the memory consumption of geometric detail information in the DDM and the ability to animate the details over the base surface. We show that the presented scheme can be used effectively to generate highly complex renderings and animations, in real time, on modern graphics hardware. The capabilities of the proposed method are demonstrated for both rational parametric base surfaces and polygonal base surfaces.  相似文献   

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