Abstract: Texture rendering is the key to the scene reality in urban visualization, and it limits the development of urban visualization, as excessive quantities of texture data are needed, which means network traffic and power consumption on mobile terminal. This paper proposes a multilevel of details among same layer texture techniques used in    cubic texture rendering, named LOD-in-IBR. Because the information selection strategy of the human visual system is different when facing vary areas, the texture data with lower resolution are used to reappear low concerned area, so as to reduce the texture data and the resource consumption of the mobile terminal. The scene area is distinguished by information entropy of image texture, the multi-resolution is used to reappear different areas in order to achieve the multilevel of details among the same layer. This paper puts forward iterated bi-cubic interpolation algorithm to eliminate the block effect of which image scaling rate is less than 0.5. Using the proposed method, the texture data needed are reduced by 30% and the time of rendering panorama is reduced by 30% with no visual perception change when texture rendering.

Key words: cubic panorama, image information entropy, texture rendering, multilevel of details among same layer

摘要： 城市可视化中的纹理再现，是场景真实性的关键。纹理再现通常需要大量的纹理数据，对于资源受限的移动终端，意味着巨大的网络流量和电量消耗，成为制约城市可视化技术在移动终端应用的瓶颈。提出一种多级纹理细节的立方体全景纹理再现技术（LOD-in-IBR）。根据人眼视觉系统信息选择策略中对场景各区域关注度存在的差异，用较低分辨率的纹理数据再现关注度较低的区域，从而减少所需的纹理数据，降低移动终端的资源消耗。场景各区域用图像纹理的信息熵进行区分，按照信息熵的大小对场景各区域分类，不同类别的纹理采用不同的分辨率进行再现，使之达到全景图像的同层次多级细节。对于缩小（分辨率降低）比例小于0.5以上的部分所产生的块效应，用双三次迭代插值算法进行优化。实验证明该方法在不引起视觉感知变化的条件下，再现所需的纹理数据减少30%，全景平均渲染时间减少30%。

关键词: 立方体全景, 图像信息熵, 纹理再现, 同层次多级细节