Abstract: Rendering outdoor scene with high fidelity is a challenging problem due to the complexity of the daylight illumination model involved.This paper presents an efficient hybrid strategy utilizing both the geometry-based rendering and the image-based rendering.Further more，a scheme developed from the image similarity technology can dramatically reduce the data demanded by the common image-based rendering.In the first pass，a simple model of reflectance and material are used to render an approximate image of the scene.Then，this result is refined by an image-based rendering method which supplies effects beyond the geometry-based rendering.In this pass，the key idea is using rather image features than images.So，the huge data of images is not necessary.This strategy gets good balance between the realism，rendering speed and the size of the data.Finally，the images of buildings under daylight are generated to demonstrate the utility of the proposed technique.

摘要： 由于日光模型的复杂性，逼真地绘制日光照射下户外场景的真实感图像是一个困难的问题。目前的绘制方法或者因为采用的模型过于简单而真实感程度差，或者绘制过程过于复杂耗时而影响其应用。应用图像相似度理论，提出了一种综合使用基于几何和基于图像的混合绘制方法。绘制过程分为两步，首先，使用简单的光照模型近似绘制场景，然后，采用基于图像的绘制和处理方法补充第一步无法表现的效果。由于采用了基于图像相似度理论的方法，能够克服基于图像绘制技术需要处理巨大数据量的缺点。用这种两步法绘制自然光照下的户外景物，只需要简单的光照模型和物体材质属性以及很少的数据存储量。该方法在真实感程度、绘制速度和数据存储量三者间取得了比较好的平衡，绘制建筑物的实验证明了方法的有效性。