虚拟广告系统一致光照技术研究*

作者：陈临强，李云霞，丁文强，杨盼 日期：2009-04-21/span> 浏览：3137 查看PDF文档

虚拟广告系统一致光照技术研究*

陈临强，李云霞，丁文强，杨盼
（杭州电子科技大学 图形图像研究所，浙江 杭州 310018）

摘要：光照一致性是衡量虚拟广告系统性能的一个重要环节。针对室外运动场景，主要采用了交互指定和自动恢复相结合的方法来恢复太阳光照。首先利用球场的特征点在图像坐标系与世界坐标系上的匹配关系计算出真实摄像机的参数；根据摄像机参数和场景中已有的物体及它们的阴影坐标来恢复主光源；并计算出虚拟物体在所求光源下光照效果的过程。研究结果表明，该方法实现相对简单，计算量较小，通过少量的人机交互就能方便快捷地生成较为接近现实的光照效果。
关键词：虚拟广告系统；光照一致性；虚拟摄像机；平面阴影
中图分类号：TP273文献标识码：A文章编号：1001-4551(2009)04-0066-05

Consistent illumination problem in virtual advertisement system
CHEN Ling-qing, LI Yun-xia, DING Wen-qing, YANG Pan
(Institute of Graphics and Image, Hangzhou Dianzi University, Hangzhou 310018, China)
Abstract: One of the important key to the virtual advertisement system is the consistent illumination of virtual objects with respect to the real environment. Aiming at the outdoor scene, an interactive appointment and automatic resume to rebuild sunlight was presented. Camera parameters according to the correspondence of feature points both in the image coordinates and the world coordinates with the camera calibration technology was firstly caculated. Then the main position of light source was gotten from the two erectness object and their shadows. Finally, the illumination effect of the virtual object in the light source with the position of virtual object and camera parameter was computed. The experimental results show that, it is relatively simple to apply this method, and it can produce a closer reality illumination effect quickly through a few man-machine interactions.
Key words: virtual advertisement system; illumination consistent; virtual camera; planar shadow
参考文献(References):
［1］王建宇,刘哲,周献中,等.虚拟广告系统关键技术研究［J］.系统仿真学报,2005,17(7):1686-1689.
［2］FOURNIER A. Illumination Problems in Computer Augmented Reality［D］．University of British Columbia,1994:1-21.
［3］KONTTINEN J, PATTANAIK S, HUGHES C E. Real-time illumination and shadowing by virtual lights in a mixed reality setting ［EB/OL］.［2005-07-14］.http://graphics.cs.ucf.edu/MAR-Sumant.
［4］KANBARA M, YOKOYA N. Real-time estimation of light source environment for photorealistic augmented reality［C］//Proceedings of the 17th International Conference on Pattern Recognition,2004:911-914.
［5］WANG Y, SAMARAS D, Estimation of multiple directional light sources for synthesis of augmented reality images［J］.Graphical Models,2003,65(4):185-205.
［6］周雅,闰达远,王涌天,等.一种增强现实系统的三维注册方法［J］.中国图象图形学报,2000,5(5):430-433.
［7］SALVADO R E, CAVALLARO S, EBRAHIM I T. Cast shadow segmentation using invariant color features ［J］.Computer Vision and Image Understanding,2004,95(2):238-259.
［8］NAKAMAE E, HARADA K, ISHIZAKI T. A montage method: the overlaying of the computer generated images onto a background photograph ［C］//In SIGGRA PH’86, Addison-Wesley Longman, August Dallas,U.S.A.1986:207-214.
［9］CROW C. Shadow algorithm for computer graphics［J］. Computer Graphics,1977,11(2):242-248.
［10］SLATER M, STEED A.计算机图形学与虚拟环境［M］.程成,徐玉田,译.1版.北京:机械工业出版社,2004.